Transistorisierter Tisch-Analogrechner RAT 700 — Beschreibung und Bedienungsanleitung

Complete English translation of the original German-language document (66 pages).

Transistorized Desktop Analog Computer RAT 700 — Description and Operating Instructions

(Reprinting and reproduction, including extracts, require authorization.)

General Information
Mechanical Construction / Equipment / Accessories / Additional Devices
Theory of Operation
- 3.1 Computing Amplifiers
- 3.2 Coefficient Potentiometers
- 3.3 Parabola Multiplier
- 3.5 Free-Running Diodes
- 3.8.2 Self/External Triggering
- 3.8.3 Pause Switch
- 3.3.1 Compensation Measuring Device / Power Supply
Technical Data
Operation
- 5.1 Installation
- 5.2 Switching On
- 5.3 Programming
- 5.4 Operating Modes
- 5.5 Using the Compensation Measuring Device
Maintenance
- 6.1 Checking the Indicators and Control Lamps
- 6.2 Checking the Power Supply
- 6.3 Checking the Computing Amplifiers
- 6.4 Checking the Function Generators
- 6.5 Checking the Multipliers
Subsequent Ordering
Fault-Finding
- 8.1 Fault Recognition
- 8.2 Fault Localization
- 8.3 Fault Correction
- 8.4 Fault-Finding Table

Preface

The present description and operating instructions are intended to inform users of the desktop analog computer RAT 700 about its construction, its theory of operation, and its technical data, and to enable them to commission and operate this device.

While this book deals fundamentally only with the technical aspects of the computer, a separate Teaching Guide for Analog Computers is available for its practical use.

The description contains, organized in the appropriate sections of the chapter “Theory of Operation,” relevant circuit diagrams. Regarding these diagrams it should be noted that all switches and relays are shown in their de-energized or de-actuated state, independent of the operating states depicted in the individual illustrations, in accordance with DIN standards.

The chapter “Operation” is, in the interest of maximum clarity, written predominantly in the form of instructions whose sequence corresponds to the correct order of the required actions. It enables immediate commissioning of the computer without knowledge of the remaining parts of the description.

For common faults that the user may encounter during operation, the “Fault-Finding” chapter provides information that enables the user to correct such faults themselves without having to call for service assistance.

1. General Information

The desktop analog computer RAT 700 contains all computing elements required for a complete analog computer as well as all devices necessary for their operation. Its complete transistorization results in significant advantages over tube computers, in particular: a substantial reduction in weight, volume, and power consumption. A climate-control system, which is often required for tube instruments, becomes superfluous — indeed, even a fan inside the enclosure is unnecessary. The computer is thus portable, and even when expanded into larger systems, the space requirement remains small. The exclusive use of semiconductor components, whose service life is extremely long, ensures high reliability and operational safety. The design of the computer is such that the machine population — i.e., the quantity of computing elements installed — can be freely chosen between the minimum configuration and the full configuration given in the table below, depending on requirements.

Minimum Configuration and Full Configuration:

Component	Min. Config.	Full Config.
Integrators/Summers	8	8
(in function generator)	0	0
Computing potentiometers	20	20
Comparators	0	2
Relays for comparators	0	2

Falling below the minimum configuration stated in the table is possible but is only practical in special cases. An existing computer with fewer elements can at any time be expanded by plugging in the appropriate plug-in units. If the machine population of a single computer is insufficient for solving larger problems, multiple computers may be connected in parallel. Interconnected computers can be centrally operated.

For displaying computation results, an oscilloscope, a pen recorder, or a digital voltmeter may be connected. Steady-state computing results can also be read using the built-in compensation measuring device. For photographing oscillograms, no special photographic attachment is required. During photography, the computing process can be triggered from the photographic apparatus.

2. Mechanical Construction

The nature of analog computers requires a larger number of computing elements to be housed and the desire for flexible configuration leads to a suitable plug-in module system. The following types of modules are used:

Plug-in units in printed-circuit technology
Mounting units with magazines for plug-in units
Plug-in drawers for plug-in units or mounting units

These modules are housed in the RAT 700 desktop chassis (Figure 1). The upper drawer RVN 700 (Figure 2) accommodates the computing amplifier mounting unit RV 700 and the power supply mounting unit NG 700.

In the middle is the function generator drawer FG 700 with two function generators (Figure 3). The lower section of this drawer holds the potentiometer field, for which two versions are available and which can be interchanged at will: the potentiometer field Pf 1700 (Figure 4) with 20 single-turn potentiometers, or the potentiometer field Pf X 700 (Figure 5) with 20 ten-turn potentiometers.

In the minimum configuration and other configurations of the computer without a function generator, a blank panel LP 700 is inserted in place of the function generator drawer. The potentiometer field is then located below the blank panel.

The lower drawer PB 700 (Figure 6) contains the programming field and the control panel. In addition to the computing resistors, capacitors, diodes, and relay contacts for comparators, it also accommodates the electronic components of the control panel.

The configuration of the drawers or mounting units with plug-in units is shown in the following table.

Configuration Table:

Component	RAT 700 G (Min. Config.)	RAT 700 V (Full Config.)
Mounting units
Computing amplifier and power supply — RVN 700	1	1
Computing amplifier — RV 700	1	1
Main amplifier — HA 7A	10	15
Auxiliary amplifier — HI 7A	10	15
Chopper — Ch 700	6	8
Power supply — NG 700	1	1
Stabilizer — NS 7A	2	2
Stabilizer — NS 7B	2	2
Stabilizer — NS 7C	1	1
400 Hz power generator — GE 7A	1	1
Function generator drawer
FG 700 (2 function generators)	1	1
Main amplifier — HA 7A	4	4
Auxiliary amplifier — HI 7A	4	4
Voltage divider — FG 7A	2	2
Diodes, positive — FG 2A	2	2
Diodes, negative — FG 2B	2	2
Zero-point diodes — FG 3A	2	2
Chopper — Ch 700	2	2
Blank panel — LP 700	1	—
(in place of function generator drawer)
Potentiometer field Pf 1700 (with 20 single-turn pots.)	1	1
Potentiometer field Pf X 700 (with 20 ten-turn pots.)	—	—
Programming field and control panel — PB 700	1	1
Schmitt trigger — ST 7A	1	1
Parabola multiplier — PM 7A	4	4
Parabola multiplier — PM 7B	4	4
Interconnecting cable — VK I 700	1	1
Interconnecting cable — VK 700	1	1

The electrical interconnection of the drawers with one another is divided into a fixed wiring harness for the power supply and flexible cables for connecting the computing elements. The connection of the drawers and mounting units to the fixed wiring is made via knife-edge contacts which, when inserted into the chassis, are guided by locating pins into the spring contacts of the fixed wiring.

Similarly, the plug-in units are equipped with knife-edge contacts that are plugged into the spring contacts of the magazines in the drawers or mounting units. For subsequent expansion of the instrument, no soldering work is therefore required in any case.

Accessories

On the rear panel of the instrument there is a row of spare parts such as lamps and fuses as well as some tools such as screwdrivers for zeroing the computing amplifiers and lamp and card extractors. A cable rack on the left or right side panel of the computer is provided for storing the patch cords used for programming. Two-pole and four-pole shorting plugs are required for switching operations; two-pole shorting plugs additionally serve to create short connections. A repeat plug considerably simplifies programming of the repetitive-mode computer.

The accessories in the following configuration are standard:

Item	Quantity
Switching plugs, four-pole	40
Shorting plugs, two-pole	2
Multiple couplings	1
Flex-to-Schuko power cord	1
Set of patch cords, consisting of:
— 20 patch cords, 0.15 m long	1
— 20 patch cords, 0.22 m long	1
— 20 patch cords, 0.40 m long	1
— 10 patch cords, 0.60 m long	1
— 10 patch cords, 1.50 m long	2
Resistor plugs (red), 500 kΩ	3
Capacitor plugs (blue), 300 pF	1
Diode plug (black)	1
Cable rack	1
Repeat plug	1
As required: parallel connection cable	—

Additional Devices (optional):

Item	Notes
Oscilloscope
Photo attachment
35 mm camera, from Astro	1
Macro extension ring	2
X-Y plotter
Mobile desk for desktop computer
Oscilloscope mounting bracket
Magnetic tape analog memory — OMS 700 to OMS 700
MAS 2412

[Figure 1: Configuration and dimensions of the desktop analog computer]

[Figure 2: Computing amplifier and power supply mounting unit RVN 700]

[Figure 3: Function generator FG 700]

[Figure 4: Potentiometer field Pf 1700]

[Figure 5: Potentiometer field Pf X 700]

[Figure 6: Programming field and control panel PB 700]

[Figure 7: Rear view of the desktop analog computer (with plug-in units removed)]

3. Theory of Operation

3.1 Computing Amplifiers

[Figure 8: Computing amplifier mounting unit RV 700]

The computing amplifiers serve to carry out the linear computing operations of addition, integration, and sign inversion.

In their basic principle they are high-gain, feedback DC amplifiers whose loop gain is so large that the transfer function is determined solely by the passive feedback elements. Figure 9 shows the principle of the computing amplifier. The zero-point stability necessary for the DC amplifier is achieved by means of a drift-free AC auxiliary amplifier. The error voltage arising from the zero-point error of the main amplifier is amplified by the auxiliary amplifier and fed back into the main amplifier in such a way that the original error is reduced. Before amplification, the error voltage is modulated by a chopper onto a carrier frequency of 400 Hz and, after the amplifier, demodulated by a phase-sensitive rectifier. This method has the additional advantage that the gain for low frequencies equals the product of the gain V of the main amplifier and the gain A of the auxiliary amplifier.

The computing error of the computing amplifier components is less than 10⁻³; the phase error is less than 10⁻¹ up to a frequency of 30 Hz. Figure 10 shows the loop gain as a function of frequency. From the diagram it can be seen that the computing error caused by finite gain remains less than 0.1% up to the genuinely high frequency of 1000 Hz. Figure 11 shows the influence of temperature on the drift. The drift remains below 20 μV at ambient temperatures up to +40°C.

[Figure 9: Principle of the computing amplifier]

The main amplifier and the auxiliary amplifier are constructed on separate plug-in units (Figure 12). The chopper is also plug-in-capable. The chopper has two contacts, so that one chopper can be used for two computing amplifiers. Up to 15 computing amplifiers — i.e., 15 main amplifiers, 15 auxiliary amplifiers, and 8 choppers — are housed in the upper drawer in the RV 700 mounting unit. Four further amplifiers are located in the function generator drawer, where they serve to sum the piecewise-linear segments.

[Figure 10: Loop gain of the computing amplifiers]

The computing amplifiers in the upper drawer can be operated at will as open amplifiers, inverting amplifiers, or summers, and some of them also as integrators.

By an open amplifier is understood the computing amplifier without feedback. For certain computing circuits, open amplifiers are required whose gain factor is specified by the circuit. For these cases the amplifiers are equipped with particular output sockets. Since in an open amplifier the output voltage can easily exceed the permissible range, and simultaneously one must prevent the amplifier input from being overloaded, in the operating mode “Pot Set” the feedback is automatically switched in to limit the gain factor. This is accomplished by relays located in the lower drawer of the instrument.

[Figure 11: Influence of temperature on drift]

An inverting amplifier is used when a signal polarity must be reversed. In practice, one uses a summer-connected amplifier and applies the voltage to be inverted to one input with a weighting factor of 1.

[Figure 13: Summer]

In the integrator, the feedback resistor of the summer is replaced by a capacitor. In the desktop analog computer this is achieved in the switchable summer/integrators (Figure 14) by switching a plug (St 1) from the “summer” position: a second plug (St 2) connects the capacitor with the summing junction, and the feedback resistor is simultaneously disconnected (St 1 contacts 0). The initial condition (I.C.) — that is, the integration constant U₀ — is set by charging the capacitor to a corresponding voltage. The voltage is taken from a coefficient potentiometer and applied to the white socket “A” of the summer/integrator.

[Figure 14: Computing amplifier switchable as summer and integrator]

The relay contact Ps is, as with the summers, actuated exclusively during the setting of the coefficient potentiometers. Contacts h and r, on the other hand, serve to fix the start and end of integration and to halt integration during the process. In the latter case the integrator acts as a memory, so that the output voltage remains available for further computation. The contacts are labelled in the pause position. During integration contacts h (hold → Compute) are closed and r (reset → I.C.) are open. In the pause position both contact sets are open, so that the integrator capacitor retains its charge. During the initial-condition phase, contacts r (IC) are closed and h (Compute) are open: the capacitor is then charged to the initial-condition voltage.

In the repetitive computing mode — characterized by rapidly alternating Compute and I.C. phases — the contacts are always controlled by the Schmitt trigger (comparator), whose function is described in detail in Section 3.8. The relay control voltage is derived from the voltage network of the control panel; in single-shot and repetitive computing, it is produced by a relay or the Schmitt trigger. In single-shot operation, all contacts return to the pause position at the end of the computing time. In single-shot and repetitive computing the contacts h serve to switch the amplifiers to Compute while the contacts r simultaneously disconnect the I.C. voltage and connect the amplifier inputs to the problem circuit, and vice versa.

Amplifier 15 serves as integrator in the repetitive-computing mode for the special purpose of deriving the time base — i.e., the duration of the rise of an output voltage from −10 V to +10 V. The circuit required for this (Figure 15) can be set up very simply with the aid of a repeat plug. In this circuit the potentiometer located at machine unit 20 is connected to the amplifier input. The rate of rise of the output voltage, and thus the computing time, is set with this potentiometer by an appropriate choice of the integration capacitor. At the output of the amplifier a Schmitt trigger (i.e., a specialized comparator) is connected, which responds when +E (+10 V) is exceeded and thereby controls the relays that switch to pause and restart computation, so that repetitive computing occurs. The precondition is of course that the “Rep. Compute” key is pressed.

[Figure 15: Circuit connection of amplifier 15 through the repeat plug]

If the computer is switched to the operating mode “Dauerrechnen” (continuous computation) but the repeat plug is nevertheless inserted, only amplifier 15 operates repetitively. This possibility is used primarily when the output voltage of amplifier 15 is used as an accurate time-base deflection voltage for an oscilloscope on which a computation result is to be displayed. In parallel operation of multiple computers, the repetitive-mode master — both in repetitive-computing mode and when using amplifier 15 as a time-base generator — must be set only at the command instrument.

[Figure 16: Amplitude and phase error of the computing amplifiers as a function of frequency]

Overload Relay (Übersteurerungsrelais)

Each amplifier unit in the upper chassis insert is connected to an overload relay. This relay switches on an overload lamp labeled with the amplifier number as soon as the respective amplifier is overloaded. The overload relay also makes it possible to automatically halt the computation at the moment of overload. The circuitry required for this can be enabled or disabled as needed. To enable it, the two adjacent sockets labeled “AS” on the programming field simply need to be connected to each other.

The overload relays and overload lamps are located on the front panel of the mounting unit V700 in the upper chassis insert. The potentiometers for the zero adjustment of the amplifiers are also mounted there. All other elements belonging to the amplifiers — the relays, the computing resistors, and the integration capacitors — are located in the lower chassis insert. All connections of the amplifiers in the upper insert are routed to the programming field, which is located on the front panel of the lower insert.

3.2 Coefficient Potentiometers

The ten-turn potentiometers of the potentiometer field PsX 700 differ from the single-turn potentiometers of the optionally available potentiometer field Pf 1700 in their higher setting accuracy. They are also continuously adjustable.

The circuit and the connections of the potentiometers of both fields to the programming field are identical. Both fields also have the same dimensions, so they are interchangeable with each other.

The wiper terminals of four potentiometers are led separately to the programming field; the remaining ones are connected to +10 V (ground reference). The sockets for the input terminals are dark green, those for the wiper terminals are orange, and those for the low-end (ground) terminals are light green. The potentiometers are protected by series resistors so that they cannot be destroyed by incorrect connections. Each potentiometer is assigned a pushbutton via which the respective potentiometer is disconnected from the machine during adjustment and connected to the compensation measurement device.

3.3 Parabola Multiplier (Parabolmultiplikator)

The four parabolic segments of the multiplier are formed by secant approximation.

For each parabolic segment, six diode sections are used. Compared to an ideal parabola y = x², the approximated parabola satisfies y + F = x², from which the error follows as F = y − x², where F = F(y). Figure 17 shows the measured error of a parabolic segment. Here x corresponds to the range 0 ≤ x ≤ E of the input voltage (E = machine unit, 10 V), and y denotes the output voltage, likewise in the range 0 ≤ y ≤ E.

The error measured in volts is likewise referred to the simple machine unit. It should be pointed out that various values of the error of an analog-computer-approximated parabolic segment are found in the literature or in product literature, which are referred to E…0…+E, i.e., to 2E, i.e., to the entire working range. For comparison with these values, the values given here must be divided by 2; the maximum error then amounts to less than 0.15%.

[page 22: Figure 17 — Measured error of a parabolic segment]

[page 23: Figure 18 — Wiring diagram of the mounting unit, computing amplifiers]

The four multipliers are located in the lower chassis insert. One multiplier network is accommodated on two plug-in amplifier cards. The computing amplifiers of the upper insert are used as amplifiers. For each of the three computing amplifiers connected in parallel at the programming field, dark green input sockets are provided for the quantities x, t, 1/y and v. The three parallel-connected output sockets of the multiplier are dark green. The socket (G) of the multiplier that is to be connected to an open amplifier is positioned such that the connecting lead is very short. One output socket of the multiplier is to be connected with an output socket of the open amplifier, so that the feedback resistor belonging to the multiplier, which simultaneously provides good temperature compensation of the approximated parabolic segments, is connected.

[page 24: Figure 19 — Schematic diagram, multiplier block / handwritten annotations]

[page 25: Figure 20 — Assembly diagram of the parabola multiplier]

3.4 Function Generator (Funktionsgeber)

The function generator generates an arbitrary function with up to 19 sections by diode approximation of the function curve. The breakpoints on the abscissa are equidistant. Within each of the two function generators of one insert, two computing amplifiers N_A and N_B are built in, so that each diode section can be set to both positive and negative slope. The setting of a function generator is accomplished with 21 potentiometers, of which the middle one — “0” — produces an ordinate shift. This is possible over the entire working range −E ≤ U ≤ +E. The input socket of the function generator is light green, the parallel-connected output sockets are light orange. Figure 22 shows the basic circuit diagram, Figure 23 the wiring plan of the function generator.

[page 26: (continued from section 3.4)]

3.5 Free Diodes

To enable the generation of special functions, the RAT 700 computer contains free diodes. The cathode and anode of each diode are connected to two parallel-connected sockets of the same color on the programming field. Polarity and circuit configuration are visible from the symbolic labeling on the front panel. The diodes are arranged on the front panel so that they are located near the three potentiometers and amplifiers with which they will most often be used together. The special functions that can be generated are manifold, e.g.: limiter functions, hysteresis, transmission losses, step functions, zone functions, dead-band conditions, and others.

3.6 Comparators

Comparators are used to switch a computed quantity as a function of a second quantity. The built-in computing relays serve to construct the comparators. The two computing relay coils have the brown sockets of the programming field assigned to them. Both the windings and the contacts of the relays can be connected to the sockets. The labeling is unambiguous. Polarized relays with two-sided rest positions are used as relays. The switching of the contacts occurs by reversing the direction of current in the winding. The contact, however, remains in its position when the excitation current goes to zero. The assignment of the contact position is evident from the labeling. If a voltage whose polarity corresponds to the polarity of the labeling is applied to the winding, the contact moves to the position designated with ”+”.

[page 28: Figure — (circuit or wiring diagram)]

3.7 Programming Field (Programmierfeld)

At the programming field, the inputs and outputs of all computing elements, as well as the machine units (+10 V and −10 V), are accessible. Additionally, the disconnect points for switching the computing amplifiers and for interrupting the reset lead are located there. All connections to a computing amplifier are gathered in one busbar field of the programming field corresponding to the amplifier. The assignment of the sockets to the computing elements is clearly shown in Figure 24. The meaning of the colors and labeling of the sockets is described individually below.

3.7.1 Socket Fields (Buchsenfelder)

The individual fields of the computing amplifiers are labeled with the corresponding amplifier numbers. The input sockets are dark green, the outputs are red. The labeling of the input sockets indicates the various weighting factors. The socket labeled “S” represents the input summing junction. The connecting line between the red sockets indicates the parallel connection of these sockets.

The disconnect points for switching between summing amplifier / integrator lie at white sockets. When operating such an amplifier as a summing amplifier, the two sockets identified by the summation symbol are connected to each other with an appropriate switching plug. When operating the amplifier as an integrator, the switching plug is inserted into the sockets grouped around the integral symbol. The integration capacitor is selected by bridging the white sockets, which are symbolically labeled on the front panel according to the conditions for the weighting factor, or integrated with “10”, and thus connected. The initial condition sockets for the integrator are labeled “A”.

For the non-switchable summing amplifiers, the white sockets represent the disconnect point of the feedback path. Socket R lies on the feedback resistor, socket G lies at the amplifier.

The sockets of the two function generators are labeled with the corresponding numbers of the function generators with “F1” and “F2”. The input sockets are dark green, the output sockets are red.

The dark green input sockets of the multipliers are labeled with the designations of the parabolic segments. Two parallel-connected sockets are assigned to each input.

The white socket labeled G serves for the connection to an open amplifier necessary to complete the multiplier network. It is connected with socket G of the amplifier.

The red sockets are internally connected to the feedback resistor of the multiplier. When making the connection with the amplifier, they must be connected to the output of that amplifier. Since the amplifier output is simultaneously the output of the completed multiplier, five output sockets are available in total: two in the socket field of the multiplier and three in the socket field of the amplifier.

Coefficient Potentiometers

The connection sockets of the coefficient potentiometers are labeled individually with the numbers of the respective potentiometers. The wipers of the potentiometers are connected to orange sockets. The start (low end) of each potentiometer is grounded, with the exception of potentiometers 5, 10, 11, and 16. The end contacts are at the light green sockets. The starts of the un-grounded potentiometers are connected to the dark green sockets of the socket fields of the potentiometer section.

The connection sockets for the free diodes are yellow. The polarity of the diodes is evident from the symbolic labeling on the front panel.

The machine voltage +E (+10 V) is connected to the red sockets, the machine voltage −E (−10 V) to the blue sockets.

Comparator Relays

The connection sockets for the two comparator relays are brown. The assignment of the connections is evident from the symbolic labeling.

3.7.2 Cells (Zellen)

Behind the programming field, computing resistors and feedback networks of four different types are accommodated in seven cells (Figures 25–28). The cells contain the relay contacts required for switching the computing amplifiers between the different operating modes (see 3.8.1). The connections among the cells and with the sockets of the insert are shown in the wiring diagram (Figure 29). The wiring of the sockets not connected to cells is also shown there.

[page 31: Figure 25 — Wiring diagram of Cell Type I] [page 32: Figure 26 — Wiring diagram of Cell Type II] [page 33: Figure 27 — Wiring diagram of Cell Type III] [page 34: Figure 28 — Wiring diagram of Cell Type IV]

3.8 Operating Unit (Bedienergerät)

The operating unit contains all elements required for controlling the computer. Additionally, it features a measurement device that operates according to the compensation method and permits very accurate measurement of voltages up to 10 V.

3.8.1 Operating Mode Selector Switch (Betriebsarten-Wahlschalter)

The operating mode selector switch consists of a six-element pushbutton assembly. Pressing the buttons activates the relays that take over the further switching functions. The buttons are mechanically interlocked so that only one operating mode can be set at a time. Depending on the operating mode, the relays H, R, and P are correspondingly energized (black) or de-energized (white) as shown in the table that follows.

[page 35: (Table and circuit details for operating mode relays)]

These relays are located at the various cells of the insert (see Figures 25–28). One set of relays is assigned to two computing amplifiers. For the sets assigned to the non-switchable amplifiers (summing amplifiers), relay H takes the role of amplifier 15; relay U takes the function of relay H; and relay V takes the function of relay R.

3.8.1.1 Continuous Computation (Dauerrechnen)

After pressing the “Dauerrechnen” (continuous compute) key, the computation runs continuously until it is interrupted by pressing another key. The computation can also be restarted after switching on the operating mode “Dauerrechnen” repeatedly without interruption, if it is connected with the repeat plug (see 3.1).

When the key is pressed, the following switching contacts (e.g., S3/3,4) and relay contacts (e.g., d3/6,7) close the following circuits:

S3/3,4: the excitation circuit (25 V) of relay D3, which thereupon pulls in
d3/6,7: the lamp circuit for lamp Lo (“Dauerrechnen”)
d3/9,10: the excitation circuit for all R-relays (r-lead)
d3/12,13: the excitation circuit for all H-relays (h-lead)

With this, the conditions for operating mode of amplifier 15 on compute are fulfilled.

S3/6,7 additionally closes the excitation circuit of relay D4.

The circuits newly switched by the relay, independent of whether it is self-controlled (Eigensteuerung) or externally controlled (Fremdsteuerung), are:

For self-control (relay F de-energized):

d4/9,10 closes via r/9,10 the excitation circuit for relay V
d4/12,13 closes via f/6,7 the excitation circuit for relay U

so that now amplifier 15 is also switched to continuous computation.

When the computer is connected with the repeat plug to the relay, amplifier 15 operates repetitively, i.e., through its interaction with the Schmitt trigger, relays A, I, iH, and T (see 3.8.1.2) alternately energize and de-energize relays U and V so that the computer alternately operates in the “Rechnen” (compute) and “Pausen” (pause) states. The relay contacts d3/12,13 and d3/9,10 remain connected to the excitation voltage.

For external control (relay F energized): repetitive computation of amplifier 15 is not applicable. For this reason, relay V is connected in parallel with relay R via contact f/8,9, and relay U is connected in parallel with relay H via contact f/5,6.

3.8.1.2 Repetitive Computation (Repetierendes Rechnen)

In this operating mode, the computer is automatically switched alternately between the states corresponding to the operating modes “Rechnen” (compute) and “Pausen” (pause).

The trigger for computation is amplifier 15, connected with the repeat plug. The output voltage of this amplifier is fed via the repeat plug to the input of the Schmitt trigger (ST input). The Schmitt trigger activates relay A as soon as the amplifier output voltage exceeds a threshold. Relay A initiates the change from “Rechnen” to “Pausen”. The compute time depends on the integration time constant of amplifier 15 and the threshold of the Schmitt trigger, and can be adjusted by means of the potentiometer (coefficient potentiometer 20 — integration potentiometer, adjustable from outside).

The pause time is similarly determined by one of several selectable capacitors through the pause capacitor switch (S8). The currently selected capacitor is charged during the compute phase and discharges on the following pause. After its discharge, relay A becomes de-energized, whereupon the switching from “Pause” to “Rechnen” is now initiated. In principle, any amplifier can be used as a time generator (instead of amplifier 15 connected with the repeat plug), provided that the individual computing chains are programmed accordingly.

After switching on the operating mode “Repetierendes Rechnen” with the key “Rep. Rechnen,” the following circuit changes occur:

S4/4,5 closes via d6/8,9 the excitation circuit of relay D4 (the relay is connected via d5/11,12 to 25 V)
d4/6,7 applies voltage to lamp Lo1 (in the key “Rep. Rechnen”)
d4/9,10 closes the excitation circuit of all R-relays via r-lead and the excitation circuit of relay V via t or d3/8,9, depending on whether relay F is energized or de-energized (self/external control)
d4/12,13 closes the excitation circuits for relays I and iH via t/5,6
ih/6,7 closes via t/5,6 a holding circuit for relays I and iH; this disconnects (if an oscilloscope is connected to the computer) the blanking connection of the oscilloscope
ih/9,10 connects the recorder (if connected to the computer)
d4/12,13 closes via t/5,6 and d3/11,12 the excitation circuit for all H-relays (h-lead)
d4/12,13 closes the excitation circuit of relay U via t/5,6 and f/6,7, or f/5,6 (depending on whether relay F is energized or de-energized, i.e., self or external control)

The conditions for the state “Rechnen” are thus fulfilled. Amplifier 15 integrates. The output voltage rises to the Schmitt trigger threshold. The Schmitt trigger activates relay A.

Relay A initiates the change to “Pause”:

a/8,9 opens the holding circuit for relay D4 (via d4/12,13 closed). Relay D4 drops out. The disconnection of the R-relays and H-relays, and of relays U and V, initiates the change to “Pause”. Since relay A is now energized, its contact a/5,6 acts on the release of the spring-loaded key of the optionally connected recorder (via the jack “SP” — opens the pen-lift circuit)
a/9,10 closes via S7/6,15 the excitation circuit of relay T, but only in self-control; in external control, relay T is switched off via the command switch at 12b7 or 13b7
t/5,6 opens the excitation circuit of relays I and iH
t/5,6 opens the excitation circuit of all H-relays and R-relays (the relays of U and V are no longer supplied)

Now the pause interval takes place. During the pause, the pause capacitor discharges to zero. Relay A drops out.

a/9,10 opens the excitation circuit of relay T
t/5,6 re-closes the circuits for relays H, R, U, V, I, and iH

The conditions for “Rechnen” are once again fulfilled, until relay A again responds.

3.8.1.3 Single Computation (Einmalrechnen)

The computer executes a single computation and then automatically passes into the “Pausen” state. The pauses of the repetitive-computation sequence are used for this purpose. Amplifier 15 is also used here as a timer. Since repetitive computation is essentially a special case of single computation that repeats, the following description refers back to section 3.8.1.2. The essential difference is that after the computation has ended and the single pause has elapsed, the relay A is de-energized, and a new computation can only be triggered by pressing the “1 × Rechnen” key again.

S6/3,4 (or the flash contact of the photo input connected to the photo socket) closes briefly (the key itself does not engage) via t/8,9 and d2/11,12 the excitation circuit of relay D6
d6/12,13 closes a holding circuit for relay D6
d6/6,7 applies voltage to lamp Lo6, which is located in the key “1 × Rechnen”
d6/9,10 closes the excitation circuit of relay D4

Relay D4 now only initiates those switching operations that also initiate the start of computation in repetitive computation (see 3.8.1.2). As in repetitive computation, the computation run itself now lasts until relay A responds, via:

a/8,9 — opens the holding circuit of relay D6 closed via d6/12,13.

Relay A drops out after the corresponding pause time. A new “Pause-to-Rechnen” switch is initiated. However, a new computation run can only be triggered again by pressing the key “1 × Rechnen.”

To prevent the computer from immediately going back to repetitive computation when relay A drops out via d4/12,13, relay T is energized via a/9,10. This interrupts the connection of relay D6 with the key S6/3,4 or with the photo socket via t/8,9, so that the excitation of relay D6 required to trigger a new computation run cannot occur immediately. Via t/9,10, a holding circuit is closed for relay T, which persists as long as the key “1 × Rechnen” (S6) is pressed.

3.8.1.4 Pause (Pause)

In this operating mode, any running computation is interrupted. The key must be pressed before the start of each computation.

S2/3,4 closes the excitation circuit of relay D2
d2/6,7 applies voltage to lamp Lo2, which is located in the key
The remaining contacts of relay D2 open the holding circuits that may still be closed from the previously engaged operating mode. Relays H, R, U, and V are therefore, corresponding to the operating mode “Pause,” de-energized in any case.

[page 38: Figure 32 — Circuits for single computation (Einmalrechnen)]

3.8.1.5 Hold (Halt)

By pressing the “Hold” key, the computation is interrupted, i.e., the integration capacitors are held at their currently attained values. At the moment the hold key is pressed, the integrators that were rolling freeze in place, and the machine can then be set to perform other computing operations if required.

Relay contact S5/3,1 closes the excitation current circuit of relay D5.

S5/6,7 places the lamp L5 located in the key “Hold” at supply voltage.
S5/8,9 stops the recorder (if connected to the “St” jacks).
S5/11,12 interrupts the excitation current circuits of relays D3 and D4.

Contact D3/12,13 then:

During a preceding continuous computation in self-controlled mode of the computer (relay D3 result): interrupts the excitation current circuit of relay H and the corresponding circuit of relay U.
During a preceding continuous computation under external control of the computer (relay D3 status): interrupts the excitation current circuit of relay H and the circuit of relay U.

Contact D4/12,13 then:

During a preceding repetitive computation or time-triggered computation: interrupts the excitation current circuit of relay H and the circuit of relay U.

The relay contacts that also remain energized from the previous operating state are relays R and V.

[page 37: figure only — Fig. 33: Circuit diagram during Pause (top portion of page)]

Automatic Hold

The hold function is also triggered automatically when one of the computing amplifiers detects overload — which can occur, for example, due to a programming error or through short circuit. At the same time, the overload lamp on the front panel of the computing amplifier module lights up, clearly indicating the cause of the malfunction.

Simultaneously with the hold, the same contact of the overload relay also places a signal lead from the control unit to the relay, which feeds back to the Relay D5 winding and connects it. Relay D5 is thereby additionally energized and now effects the same two steps as when the computer is stopped manually. Mutual interference of the overload relays through this common lead is prevented by diodes.

[page 37: Fig. 33 continued — circuit diagram during Pause (lower portion)]

[page 38: figure only — Fig. 34: Circuit diagram during Hold; Fig. 35: Circuit diagram during automatic Hold]

3.8.1.6 Potentiometer Setting (Koeffizienteneinstellung / Pot. Einst.)

When setting the coefficient potentiometers, the potentiometers must be loaded as in normal operation, while the amplifiers are disconnected, in order to prevent overloading, and so that no current flows through the operational amplifier inputs. The amplifier disconnection is carried out automatically. The potentiometer to be set is selected by pressing the “Pot. Einst.” (Potentiometer Setting) key on the control unit. The energization of this potentiometer and its connection to +E occurs through key press:

S1/3,4 closes the excitation current circuit of relays D1 and DH1.
d1/6,7 places the lamp L0 located in the key “Pot. Einst.” at supply voltage.
d1/9,10 closes the excitation current circuit for all relays PS (PS lead).
d1/11,12 interrupts the changeover contact S8/11 above a previously-present holding current circuit of relays I and JH.
d1/14,15 disconnects the changeover contact S8/11 from the circuit, in order to prevent the Eichpotentiometer (reference potentiometer) R11 from being bridged by the scale selector switch at the panel.

The polarity switching of the device (from ”+” to ”−”) is additionally performed. During calibration, the Eichpotentiometer wiper is disconnected from the measuring arrangement:

dh1/6,7 places the +E wiper input of the Eichpotentiometer at +E (+ 10 V).
dh1/8,9 disconnects the input of the compensation measuring circuit from the machine.
dh1/9,10 connects the output of the compensation measuring circuit to the measuring bushing, so that the desired potentiometer can be selected and measured.

3.8.2 Self-Control / External Control (Eigen-/Fremdsteuerung)

In the sections 3.8.1.1 through 3.8.1.6 the operating mode of the control unit was described only for self-controlled operation (Eigensteuerung), without the distinction between self-control and external control (Fremdsteuerung). The essential difference between self-control and external control is that in external control mode the control circuit of the control unit’s relays is not realized through the control unit itself, but rather the betreffenden (relevant) relays of all externally controlled computers are connected with the corresponding keys of the command unit (Kommandogerät), as follows:

Relay	Via Jumper	To Key
D1 and DH1	12b1/13b1	S1/3
D2	12b2/13b2	S2/3
D3	12b3/13b3	S3/3
D4	12b4/13b4	S3/6 and S4/4
D5	12b5/13b5	S5/3
D6	12b6/13b6	S6/3

The keys of the self-control operating mode selector are thereby disconnected from ground. All switching between self-control and external control is accomplished by the “Fremd” (External) key:

S7/17,18 places lamp L7 of the key at supply voltage.
S7/12,13 disconnects the contact S3/4 from ground, in order to prevent — during external control via the command unit — inadvertent actuation of relay D3 via relay D4 through the (possibly) depressed key S3.

[page 39: Fig. 36 — Circuit schematic of the control unit (potentiometer setting / potentiometer-Einstellung)]

[page 40: figure only — Fig. 36: Full schematic of the control unit (Stromkreisplan des Bediengerätes), showing the potentiometer setting circuit including external/self-control switching]

S7/7,8 connects the relay grounds via 12b8 and 13b8 with the other externally controlled computers.
S7/5,6 disconnects the excitation current circuit of relay F.
f5,6 switches relay U parallel to relay H.
f8,9 switches relay V parallel to relay R.

3.8.3 Pause Selector Switch (Pausenschalter)

The Pause selector switch (Pausenschalter) is used, in addition to setting the pause time, for the optional application of voltages between +E and −E to the Eichpotentiometer R11, as well as to bypass the Eichpotentiometer during calibration of the computing amplifiers. When applying a compensation voltage of 0 V (PG) to the compensation measuring circuit during the adjustment of a compensation voltage, the precision of the Eichpotentiometer R11 is used to eliminate its internal resistance.

The individual positions of the Pause selector switch are unambiguously labeled on the front panel of the control unit.

3.8.4 Compensation Measuring Circuit (Kompensations-Meßeinrichtung)

In the compensation measuring circuit, the voltage to be measured is placed at a high-resistance, independently-adjustable null-point reference voltage against which it is balanced using a freely selectable comparison voltage. The comparison voltage is provided by a precision potentiometer with a linearity of 0.1%, which is load-independent. The comparison measuring circuit is protected against overloading by a special circuit. The input of the compensation measuring circuit is normally connected to the violet bushing “M” of the programming field, but during the adjustment of the coefficient potentiometers (3.8.1.6) it is automatically connected with the currently selected potentiometer.

3.9 Power Supply (Stromversorgung)

[page 41: Fig. 37 — Photograph of the power supply assembly unit, Netzgerät NG-700]

The power supply unit (Netzgerät) is switchable for mains voltages of 110, 127, 220, and 240 V (50–60 Hz). It delivers very precisely stabilized machine supply voltages of ±10 V and ±10 V, as well as all other supply voltages. The stabilized output voltages are ±15 V, ±15 V, and 30 V for supplying the computing electronics, a lightly stabilized voltage of 25 V for relay excitation, a 400 Hz square-wave voltage of ±7 V and ±20 V for controlling the chopper and phase-sensitive rectifier, and an AC voltage of 6 V for powering the indicator and control lamps.

[page 42: Fig. 38 — Connection of the computing amplifier assembly unit to the power supply]

The machine unit is connected to the programming field and can be removed from it. For the positive machine supply voltages, red bushings are provided; for the negative supply voltages, blue bushings; and for the ±10 V supply (machine ground), 12 black bushings are provided.

Under the mains switch, which is a lighted pushbutton, is the mains fuse. The five lighted pushbutton keys, located to the left of the mains switch, are assigned to the legends “+30”, “+15”, “−15”, “+10”, and “−10”, corresponding to the stabilized output voltages, and have a three-fold function:

Illumination of a lighted key indicates that the corresponding voltage, which is protected by a fast relay, has been switched off due to a short circuit — which can, for example, occur as a result of a programming error.
By pressing (rotating) the lighted key, the failed voltage can be switched back on after the short circuit has been corrected.
When a key is pressed, the value of the voltage is shown on the instrument of the power supply unit — this also applies in the absence of a prior short circuit.

The supply voltages reach the computing amplifier assembly unit through the wiring of the upper plug-in module (Fig. 38), and via the cable bundle d4 of the chassis into the other plug-in modules. The connections of the plug-in modules to the cable bundle are shown in Figures 39 through 44 separately for each voltage for clarity. The distribution of the supply voltages within the plug-in modules can be seen in the respective wiring diagrams. The physical locations of plugs and bushings are shown in Fig. 7.

[page 43: Fig. 39 — Distribution of the machine voltage; Fig. 40 — Distribution of voltages +15 V and −15 V]

[page 44: Fig. 41 — Distribution of voltage +30 V; Fig. 42 — Distribution of relay supply voltage; Fig. 43 — Distribution of lamp voltage; Fig. 44 — Distribution of the 400 Hz square-wave voltage]

[page 45: figure only — Fig. 45: Circuit diagram (Stromlaufplan) of the power supply unit (Netzgerät)]

4 Technical Data (Technische Daten)

Computing Amplifiers (Rechenverstärker)

DC voltage gain: > 15
Average static computing error: < 0.5%
Input resistance of the inverting amplifier (for gain = 1): 500 kΩ (ambient temperature +10 °C to +40 °C)
Computing voltage: ±10 V
Permissible load: > 1 kΩ

Multipliers (Multiplikatoren)

Zero offset error: < 0.5% (referred to 10 V)
Static error: < 0.3% (referred to 10 V)
Input resistance, all inputs: > 15 kΩ
Inputs: +x, −x, +y, −y

For arbitrary functions in all four quadrants. Approximation by straight-line segments in twenty sections.

Input: f(x)
Maximum slope: < 0.5% (referred to 10 V)
Average static error: > 15 kΩ
Input resistance: > 15 kΩ

Potentiometers (Potentiometer)

Two versions, both short-circuit proof:

Version 1: 20-input potentiometer, 10 kΩ, with selector key for setting.
Version 2: 20-wirewound-turn potentiometer, 10 kΩ, with fine adjustment and selector key for setting under load.

Mains supply (Wechselspannung)

50 to 60 Hz
Output power without full load (vollbestückt): —
110, 127, 220, and 240 V

Dimensions

Height: 430 mm
Width: —
Weight with 10 computing amplifiers: approximately 67 kg
Weight fully equipped: approximately 78 kg

5 Operation (Bedienung)

5.1 Installation (Aufstellung)

The unit is supplied with built-in plug-in modules, assembly units, and plug-in boards on a table or, if desired, on a mobile table suitable for transportation. Before the first start-up, the transport securing screws — which protect the machine unit during transport — must be removed (removal and installation of plug-in modules, see 8.3.4).

5.1.1 Mains Connection (Netzanschluß)

Set the mains voltage selector to the nominal value of the local mains.
Set the appropriate fuse for the mains voltage:
- At 110 and 130 V: 4 A
- At 220 and 240 V: 0.5 A
Under the mains switch on the upper plug-in module, unscrew the fuse cap, insert the fuse, and re-screw the cap.
Connect the equipment plug (Fig. 7) to the mains via the mains connection cable.

5.1.2 Connection of an Output Device (Anschluß eines Ausgabegerätes)

To display the computation results, an oscilloscope, an XY-recorder, or both may be connected.

a) Oscilloscope

The special oscilloscope intended for the desktop analog computer is the TELEFUNKEN DC oscilloscope OMs 700.

Connect a black bushing of the programming field (ground) of the computer to the earth ground bushing of the oscilloscope.
Connect the Y-input of the oscilloscope to the green bushing “CO” on the rear of the oscilloscope to make the intensity control operable by the blanking signal. Connect the oscilloscope output bushing.
Connect the oscilloscope to the mains.

b) XY Recorder (Zweikoordinatenschreiber)

Connect a black bushing of the programming field (ground) of the computer to the earth ground bushing of the recorder.
Connect the violet bushing “St” of the programming field to the recorder’s input for triggering the pen lift.
Connect the violet bushing “Sp” with the device for lifting the pen of the recorder.
Connect the recorder to the mains.

5.1.3 Parallel Connection of Multiple Computers (Parallelschaltung mehrerer Rechner)

Connect the “Parallel connection” bushing via the parallel connection cable VK III 700 with the “Parallel connection” bushing of the respective other computer.
Press the “extern” (external) key at all devices, with the exception of the computer designated as the command unit.

With parallel-connected computers, independent operation of a single computer is not possible.

5.2 Switching On (Einschalten)

Press “Pause” key on the control unit.
Press “Netz” (Mains) key on the power supply unit.

The indicator lamps in the keys “Pause” and “Netz”, as well as the overload lamps, light up briefly. Once the overload lamps go out again, the computer is operational.

5.3 Programming (Programmieren)

Before the first operational use, it is advisable to carry out the function checks described below.

5.3.1 Building the Computing Circuit (Aufbau der Rechenschaltung)

Computing circuits are normally programmed in the “Pause” operating mode. The computing elements may also be patched during operation, provided that the computer is still functioning. The computing elements are connected on the programming field in accordance with the task at hand, using the patch cables (see the separate booklet “Computing with Analog Computers”).

5.3.2 Setting the Computing Elements (Einstellung der Rechenelemente)

5.3.2.1 Computing Amplifiers (Rechenverstärker)

Computing amplifiers usable as summers (Summatoren) or integrators (Integratoren) are switched using the appropriate changeover switches. The selection of the gain factors 1 or 10 is made with an input selector switch, taking into account the prescribed circuit rules.

To obtain open-loop amplifiers (offene Verstärker), one disconnects the two-pole short-circuit plug of each of the two-pole amplifiers. The opposing-polarity feedback (Gegenkopplung) is thereby removed.

For amplifiers 7 and 8, this disconnect point is automatically bridged by relay contacts during the operating mode “Pause.”

5.3.2.2 Multipliers (Multiplikatoren)

Multipliers are operated together with computing amplifiers. The variables that the multiplier is to process are supplied from the outputs of computing amplifiers without interconnecting any other elements (such as potentiometers or diodes).

The output “G” of the multiplier is connected with the bushing “G” of the corresponding summator (Summator). The output of the multiplier can only be taken from the output of the associated summator without intermediate connection of further elements.

5.3.2.3 Computing Potentiometers (Rechenpotentiometer)

Computing potentiometers are especially essential for coefficient generation — for precise computation accurate to the scale setting — as well as for a special setting (Einstellung) to allow for the loading of the potentiometer, so that the computation can be performed under load conditions (Belastung). The setting is performed as follows according to the prescribed procedure:

Press the “Pot. Einst.” (Potentiometer Setting) key on the control unit.
Set the precision potentiometer of the control unit to the value that the computing potentiometer to be set should have.
Press the white key on the potentiometer field assigned to the computing potentiometer to be set.
Bring the computing potentiometer into the position at which the instrument of the control unit reads “0”.

5.3.2.4 Function Generators (Funktionsgeber)

Function generators can be set in various ways. A precise procedure is achievable through the use of the compensation measuring circuit. A switching circuit (Schaltung) is provided for this purpose, shown in Fig. 46; it consists of an inverting amplifier, which serves for isolation of the potentiometers from the compensation measuring circuit to avoid feedback effects.

[page 49: Fig. 46 — Schematic for setting the function generator]

At the potentiometer (Fig. B, No. 19), the values for x are set one after another, and the individual values of the output variable y of the function generator are set in turn by adjusting the dials. For each value, the output variable y of the function generator is set by adjusting potentiometer “0” (step 0) from value 0 stepping toward value 1.0. The scale reads from 0 to −1.0; values x = 0, +0.1, +0.2, +0.3 … 1.0 for each dial, to the corresponding value of y as tabulated. The setting is done with the “Pause” key pressed, and the precision potentiometer should be set accurately one step at a time, as described under steps 4 to 7.

The necessary steps for creating the function generator setting are given below in chronological order (steps 1 through 16):

For a given function y = f(x) using a curve or table of values, in which the values x = 0, +0.1, +0.2, −0.1, −0.2, … 1.0 are listed with the corresponding values of y.
Connect (switch) the Potentiometer 19 of the function generator via an inverting amplifier to the input “a0” of the potentiometer, but not yet connect it to the machine unit.
Connect the output of the function generator with the measuring bushing “M”. This produces the circuit shown in Fig. 46.
Set the precision potentiometer of the control unit to the value of y for x = 0.
Bring the Stufenschalter (step switch) of the control unit to the position ”+ 10 V” or ”− 10 V”, depending on whether y is positive or negative.
Press the “Pause” key.
Set the potentiometer “0” of the function generator so that the instrument of the control unit reads “0”.
Now place potentiometer 19 against the negative machine supply.
—
Press “Pot. Einst.” key. Set the precision potentiometer of the control unit to 0.1.
Set potentiometer 19 so that the instrument of the control unit reads “0”.

The wiper voltage of potentiometer 19 is thereby set precisely to the value x = 0.1.

Press “Pause” key.
At the potentiometer “+1” of the function generator, set the value of y corresponding to x = 0.1, analogously as described under steps 4 to 7.
Carry out the settings for x = +0.2, +0.3, … up to +1.0, analogously as described under steps 9 to 13.
For negative values of x, proceed similarly from −0.1 through to −1.0 (note that the wiper of potentiometer 19 is placed against the positive machine supply for this, and the potentiometers “−1”, “−2”, etc. of the function generator are set accordingly).

Note that finally the potentiometers 0, 1, 2, etc. of the function generator must be properly set.

To check the accuracy of the settings, read the values entered in the given table sequence:

To avoid always having to measure the wiper voltages at 0.1, 0.2, etc. with the help of the compensation measuring circuit, potentiometer 19 is set to the appropriate value during the check procedure. A suitable tabular form is shown in Figs. 47 and as described.

Potentiometer 19	Target Value (Sollwert)	Setting Value (Einstellwert)
0.000	±E disconnect
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000	±E without potentiometer connection

[page 50: Fig. 47 — Sample table for recording the setting values for the function generator]

5.4 Operating Modes (Betriebsarten)

The operating modes are selected by pressing the correspondingly labeled lighted keys of the control unit.

5.4.1 Pause

Press the “Pause” key. This terminates any ongoing computation. The integration capacitors are charged to their initial values. In the “Pause” operating mode, the computing circuits are de-energized.

5.4.2 Continuous Computing (Dauerrechnen)

Press the “Dauerrechnen” (Continuous Compute) key.
Terminate the computation at the desired time by pressing the “Pause” key.

When using an oscilloscope as an output device, the time-base voltage of the oscilloscope can be taken from amplifier 15 (left side). Connect the output of amplifier 15 to the x-input of the oscilloscope and proceed as described under 5.4.3.1 to 5.4.3.1b.

5.4.3 Repetitive Computing (Repetierendes Rechnen)

Switch amplifier 15 as an integrator (see 5.3.2.1).
Insert the repetition plug into bushings f29/30 to a29/30 of the programming field. This produces the circuit shown in Fig. 15.
Press “Rep. Rechnen” (Repetitive Compute) key.
Set the desired time-linear change:
- d/dt of the output voltage of the amplifier with potentiometer 20 (setting of a) and step switch (two-pole short-circuit plug for computation capacitors, setting of the integration time constant k).

The output voltage of the amplifier starts, beginning at −E at t* = 0, rising linearly with rate k·a. When it exceeds +E (10 V), the Schmitt trigger fires and initiates the switchover to “Pause” and the restart of computation — i.e., repetitive cycling.

If one defines the computation time as the duration of the voltage rise, starting from −E at t* = 0 until reaching +E at t* = T, then:

T = 2E / (k · a)

Set the computation pause using the step switch of the control unit to either 0.1 or 1 second.

If integrators are used in the computing circuit whose large capacitor (k = 1) is switched in, the computation pause should be left at its current value. This is necessary in order to allow the capacitor to charge to its initial value during the computation pause. Terminate the computation process at the desired time by pressing the “Pause” key.

[page 51: formula and continued text on repetitive computing]

5.4.4 Single Computation (1 × Rechnen / Einmal Rechnen)

Insert repetition plug (or program amplifier 15 accordingly).
Press the “1 × Rechnen” (Single Compute) key.

The computation process runs through exactly once. Single computation is used in particular for photographing oscillograms or when using an XY recorder as the output device.

5.4.5 Hold (Halten)

To stop the computation, press the “Halt” key. In contrast to the “Pause” operating mode, all computing voltages remain present.
To continue computing, select the desired operating mode by pressing the corresponding key.

5.4.6 Automatic Hold upon Overload and Overloading (Automatisches Halten bei Übersteuerung und Überlastung)

If during a computation an amplifier becomes overdriven or overloaded, the computation result becomes meaningless and continued computing serves no purpose.

For such cases, automatic hold is provided. To allow this to be identified, the relays of the programming field can be interrupted by a short-circuit plug from the outside.

The hold occurs at the instant when the overload of an amplifier is detected. The overload is signaled by the overload lamp of the affected amplifier lighting up on the programming field. The automatic hold is identified (characterized) by the illumination of the “Halt” key.

5.4.7 Photographing Oscillograms (Photographieren von Oszillogrammen)

Connect the photo bushing of the control unit with the flash contact of the camera.
Set the camera to an exposure time corresponding to one computation time.
Trigger the camera.

The computation process runs through in exactly the same manner as when pressing the “1 × Rechnen” key (see 5.4.4).

5.5 Use of the Compensation Measuring Circuit (Gebrauch der Kompensations-Meßeinrichtung)

Pause selector (below the instrument) set to the polarity of the voltage to be measured: position ”+ 10 V” or ”− 10 V.”
Connect the voltage to be measured to the violet bushing “M” of the programming field.
Bring the instrument reading to 0 using the compensation potentiometer (right below the instrument).
Read off the value of the voltage to be measured on the scale of the compensation potentiometer.

6 Maintenance (Wartung)

The following maintenance operations must be performed at the intervals described below by trained personnel.

6.1 Check of Indicator and Control Lamps (Prüfung der Anzeige- und Kontrollampen)

Switch the computer off and back on again. All overload lamps of the amplifiers present must illuminate briefly. The indicator lamp of the “Netz” key must continuously illuminate in the switched-on state of the computer.
Press the six keys of the operating mode selector as well as the “exit” key on the control unit in succession. The indicator lamp of the control unit must illuminate respectively, or the lamps of the corresponding keys must light up.

6.2 Check of the Power Supply (Prüfung der Stromversorgung)

Press the lighted keys of the power supply unit labeled with the voltage values one after another. The indicating instrument of the power supply unit must show the corresponding values of the voltages.

6.3 Check of the Computing Amplifiers (Prüfung der Rechenverstärker)

6.3.1 Null Balance (Nullabgleich)

Switch all switchable amplifiers as summers (see 5.3.2.1).
Connect the output of the amplifier to be nulled with the input “10” of any summator.

The appearance of the display reading becomes then approximately zero — given the high sensitivity of the input “10” — which is close to null.

Connect the output of this summator with the violet bushing “M” (left) on the programming field.
Bring the step switch of the control unit to the position “0 V.”
Correct any deviation from 0 of the instrument reading using the null potentiometer of the amplifier to be tested, at the control unit.

The null potentiometer of the amplifier to be tested is located in the upper plug-in module at the relevant amplifier position.

6.3.2 Check of the Amplification Factor of the Summers (Prüfung des Verstärkungsfaktors der Summatoren)

Leave the switchable amplifiers in the summer configuration.
Bring the step switch of the control unit to the position “10 V.”
Set the potentiometer of the control unit to “10.”
Connect all (available) computing amplifiers one after another with the violet bushing “M”; the instrument reading on the control unit must not deviate by more than four graduation marks from 0. [page 53]

6.3.3 Check of the Integrators (Prüfung der Integratoren)

Switch the switchable amplifiers as integrators (see 5.3.2.1).
Insert the repetition plug into bushings f29/30 to a29/30.
Switch in the large time constant of the integrators.

This means the short-circuit plug of the respective amplifier (Verstärker 15 excepted) is connected through the short-circuit bushing.

Set potentiometer 20 to “F.”
Lay machine voltage +E (red bushing “+A”) and machine voltage −E (blue bushing) to the white bushing (L0) at the left side of the amplifier 01 through a dark-colored bushing “1” of the amplifier.
Press “Rep. Rechnen” key. The output voltage of the repetitive amplifier must rise linearly from −10 V to +10 V.
Proceed in the same manner with amplifiers 02, 05, 06, 10, 11, and 12.
Switch in the small capacitors of the integrators (also for amplifier 15).

The rise time is thereby reduced by a factor of 10. Connect the short-circuit bushing (Kurzschlußbügel) of each switchable amplifier (Anstiegszeit 0.1 seconds).

Proceed with positions 5 to 7.

6.4 Check of the Function Generators (Prüfung der Funktionsgeber)

Leave amplifier 15 in the configuration as integrator with repetition plug in the bushings f29/30 to a29/30.
Connect the output of the repetition plug with the input (green bushing) of the function generator F1.
Connect a further output of the repetition plug with the x-input of the oscilloscope.
Connect the output of the function generator F1 with the y-input of the oscilloscope.
Press “Rep. Rechnen” key.
The oscilloscope must display the set function as a polygon (Polygonzug) in its x-y mode. Check the function generator F2 in the same way in positions 2 to 5.

6.5 Check of the Multipliers (Prüfung der Multiplikatoren)

Supplement the multipliers after 5.3.2.2 with computing amplifiers.
Connect the output of the multiplier with the violet bushing “M” (right on the programming field).
Set the step switch of the control unit to “−10 V”, potentiometer to “0.”

[Pages 55–66: Commissioning, Fault Diagnosis, and Maintenance]

[Page 55 — continued from previous section]

Calibration Procedure (continued)

Step .4 — Using the first multiplier, perform the multiplication 0 × 1 = 0 as follows:

Apply machine voltage +E and machine voltage −E to jacks “+x” and “−x” respectively. Connect jacks “+y” and “−y” together. The instrument display on the operator unit must not deviate from zero by more than 10 scale divisions.

Step .5 — Using the first multiplier, perform the multiplication 1 × 0 = 0 as follows:

Apply machine voltage +E and machine voltage −E to jacks “+y” and “−y” respectively. Connect jacks “+x” and “−x” together. The instrument display on the operator unit must again not deviate from zero by more than 10 scale divisions.

Step .6 — Using the first multiplier, perform the multiplication 1 × 1 = 1 as follows:

Apply machine voltage +E to both jacks “+x” and “+y”. Connect the ”−” jacks together. The instrument display of the operator unit must indicate +E (maximum permissible deviation: 10 scale divisions).

Step .7 — Carry out the multiplications described in Steps .1 through .6 in sequence with each of the remaining multipliers.

7 Retrofitting (Nachbestückung)

The computer may be retrofitted with additional plug-in units. Each empty slot must be fitted with either a blank panel or supplemented with a function-generator plug-in unit. In the case of the potentiometer field, retrofitting does not normally involve inserting additional units; instead, where necessary, the potentiometer field Pf 1700 (with single-turn potentiometers) is exchanged for the potentiometer field Pf X 700 (with ten-turn potentiometers).

Removal and installation of plug-in units in the upper drawer is described in Section 8.3.4; insertion of plug-in cards into their magazine slots is described in Section 8.3.5. When retrofitting the upper plug-in unit or the function generator with computing-amplifier plug-in cards, the selector plug located beneath the power supply unit (Figure 48) must be switched. The wiring of this selector plug for the various configurations is shown in Figure 49.

Figure 48 — Selector plug for phase correction.

Figure 49 — Wiring of the selector plug for phase correction.

8 Commissioning

8.1 Error Voltage

[Section describes procedures for measuring and correcting error voltages using adjustment potentiometers accessible from the front panel. If these measures do not produce results as listed in the table, or if faults recur, or if the fault is beyond simple field correction, service is to be called or the unit is to be sent to the factory.]

8.2 Fault Localization

Once a fault has been unambiguously identified, localizing the fault proceeds as follows based on the nature of the fault symptom:

8.2.1 Failure of an Operating Voltage

Step .1 — Remove the upper plug-in unit (see Section 8.3.4). In the removed state, reconnect the unit to mains power, press the “Mains” button, and check the voltages again.

After reconnecting the removed upper plug-in unit to the mains, the flat cables from the upper plug-in unit must not touch live parts of the power supply unit. The plug connectors of the plug-in unit must not be inserted. The unit must remain physically separate from the chassis.

a) If the missing voltage is still absent: Locate the fault within the upper plug-in unit per Steps .2 and .3.
b) If all voltages are now present: The fault lies in the chassis wiring or in the other plug-in units; proceed per Steps .4 through .6.

Step .2 — Pull out the individual plug-in cards of the computing-amplifier assembly one at a time. After each removal, check the voltages again.

Pull the auxiliary amplifier Hl 1A first, then the main amplifier HA 1A.

a) If the missing voltage is still absent after removing all plug-in cards: The fault probably lies in the power supply unit; proceed per Step .3.
b) If all voltages are present after removing a specific plug-in card: The last card removed is defective and must be replaced.

Step .3 — Swap plug-in units NS 1A, NS 1B, and NS 1C on a trial basis against replacement units (or units from another instrument if available).

a) If the missing voltage is still absent: Send for service or return the upper plug-in unit to the factory.
b) If all voltages are now present: Leave the replacement plug-in units in the power supply unit and re-insert the upper plug-in unit into the instrument.

If all voltages are present when the upper plug-in unit is removed (per Step 8.2.1.1b):

Step .4 — Remove the remaining plug-in units from the chassis and re-insert only the upper plug-in unit.

a) If the missing voltage is now absent again: The fault lies in the chassis wiring; send for service or return the unit to the factory.
b) If all voltages are present: The fault lies in one of the removed plug-in units; proceed per Steps .5 and .6.

Step .5 — Re-insert the lower plug-in unit into the instrument.

a) If the missing voltage is once again absent: The fault lies in the plug-in unit just installed; proceed per Step .6.
b) If all voltages are present: The fault lies in the function generators not yet re-installed; proceed per Step .6.

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Step .6 — Insert the remaining plug-in units one after another into the instrument, checking the voltages after each insertion.

a) If the missing voltage is still absent even after removing all plug-in cards from the affected plug-in unit: The fault lies in the wiring of the plug-in unit itself; send for service or return the plug-in unit to the factory.
b) If all voltages return after removing a specific plug-in card: The last card removed is defective and must be replaced.

8.2.2 Failure of the 400 Hz Voltage

Step .1 — Remove the upper plug-in unit (see Section 8.3.4). In the removed state, reconnect to mains and press the “Mains” button.

a) If the 400 Hz voltage is still absent: The fault lies in the upper plug-in unit; proceed per Steps .2 and .3.
b) If the 400 Hz voltage is now present: The fault lies in the chassis wiring or in the lower plug-in unit.

Pull out all choppers (CH 700) and all auxiliary amplifiers (Hl 1A) of the computing-amplifier assembly one at a time.

a) If the 400 Hz voltage is still absent: The fault lies in the power supply unit or in the wiring of the upper plug-in unit; proceed per Step .3.
b) If the 400 Hz voltage returns after removing a specific chopper or auxiliary amplifier: The last chopper or auxiliary amplifier removed is defective and must be replaced.

Step .3 — Replace the power-generator plug-in unit GE 1A of the power supply unit with a replacement unit.

a) If the 400 Hz voltage is still absent: The fault lies in the remaining installed parts or in the wiring of the plug-in unit; send for service or return the plug-in unit to the factory.
b) If the 400 Hz voltage is again present: Plug-in unit GE 1A is defective; leave the replacement unit installed.

Re-insert the upper plug-in unit into the instrument, remove the function generator, and press the “Mains” button on the power supply unit in the upper plug-in unit.

a) If the 400 Hz voltage is still absent: The fault lies in the chassis wiring; send for service or return the unit to the factory.
b) If the 400 Hz voltage is again present: The fault lies in the function generator; proceed per Step .5.

Step .5 — Pull out the choppers (CH 700) and auxiliary amplifiers (Hl 1A) of the function generator one at a time.

a) If the 400 Hz voltage is still absent: The fault lies in the wiring of the function generator; send for service or return the function generator to the factory.
b) If the 400 Hz voltage returns after removing a specific chopper or auxiliary amplifier: The last chopper or auxiliary amplifier removed is defective and must be replaced.

[Page 62]

8.3 Fault Correction

8.3.1 Replacement of Defective Indicator and Control Lamps

The incandescent lamps may only be replaced with the instrument switched off. If a lamp has burned out in one of the lamp sockets, the socket must not be put back into operation until a replacement lamp is available. If no replacement lamps are at hand, the defective lamps must be left in their sockets.

The rectangular buttons of the overload indicator lamps and control pushbuttons can be snapped off using a screwdriver and snapped back in by pressing them in. The round caps of the test sockets beside the display instrument of the power supply unit and beneath the display instrument of the operator unit are screwed on. The incandescent lamps of the overload control units can be replaced by hand. A lamp-extraction tool is stored in the accessory compartment at the rear of the computer for removing miniature lamps from the operator unit and test socket positions. Replacement lamps are also stored in the accessory compartment.

8.3.2 Replacement of Fuses

a) Main Fuse

The fuse may only be replaced with the computer switched off. It is located beneath the mains voltage selector switch. When replacing the fuse, a screwdriver is used to open the fuse cover; the old fuse is removed together with its retaining clip, and the new fuse is inserted. Attention must be paid to the correct rated value of the replacement fuse element. The correct values are:

Mains 110 V or 130 V: 1 A (medium-slow)
Mains 220 V or 240 V: 0.5 A (medium-slow)

Replacement fuses are stored in the accessory compartment at the rear of the computer. If the fuse repeatedly blows, this points to an incorrect setting of the mains voltage selector (see Section 5.11) or to a fault in the supply-current distribution circuits.

b) Fuse for the 400 Hz exciter current circuit

Pull out the upper plug-in unit (see Section 8.3.4). The fuse is located on the transformer of the power supply unit. The rated value of the replacement fuse must be 0.8 A (medium-slow).

8.3.3 Replacement of Overload Relays

The relays for the overload lamps are located in the upper plug-in unit. They can be removed from their sockets after folding open the clip bail.

[Page 63]

8.3.4 Removal and Installation of Plug-in Units

Disconnect the mains plug from the mains socket and from the rear panel of the computer.
Pull out the connectors of the connecting and interconnecting cables of the plug-in unit to be removed (release the locking clip).
Remove the four captive screws on the front panel of the plug-in unit to be removed.
Pull the plug-in unit out from the front.

Before removing the function-generator plug-in unit, first remove the blank panel or the potentiometer field located in front of it.

When removing the potentiometer field and the function-generator plug-in unit, the connecting cable must be carefully drawn through by hand from the rear.

Installation:

Insert the plug-in unit from the front.

Before installing the potentiometer field, first insert the function-generator plug-in unit or the blank panel. When installing the function-generator plug-in unit and the potentiometer field, feed the connecting cable through from behind first.

Secure the plug-in unit at its front panel with the four captive screws.
Connect the connectors of the connecting and interconnecting cables in the arrangement shown in Figure 7, attaching them to the appropriate connecting strips provided for that purpose.
Fasten the rear panel of the computer.
Connect the mains cable to the instrument socket of the computer and to the mains socket.

8.3.5 Removal and Insertion of Plug-in Cards

Removal and insertion of plug-in cards must not be performed on plug-in units that are under voltage.

Remove the plug-in unit concerned as described in Sections 8.3.4, Steps 1 through 5.
Pull out the plug-in card.

Caution: With computing-amplifier plug-in cards (in the computing-amplifier assembly and in the function generators), always pull the auxiliary amplifier Hl 1A first, and then the main amplifier HA 1A.

Slide the plug-in card into the correct slot of the magazine in the plug-in unit (Figures 51 through 54), guiding it along the guide rails of the magazine. In Figure 50, the occupied slots (those already fitted) are indicated by solid lines; those still to be filled are shown with dashed lines.

Insert the plug-in card with only light pressure into the spring-loaded strip of the magazine. Do not use force. At the slightest resistance, lift the plug-in card out again and slide it back in.

Caution: With computing-amplifier plug-in cards (in the computing-amplifier assembly and in the function generators), always insert the main amplifier HA 1A first, and then the corresponding auxiliary amplifier Hl 1A.

Re-insert the plug-in unit into the chassis as described in Sections 8.3.4, Steps 6 through 10.

Figure 50 — Insertion of plug-in cards.

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Figure 51 — Populated magazine plan of the computing-amplifier assembly.

[Page 65]

Figure 52 — Population plan of the magazine in the power supply unit.

Figure 53 — Population plan of the function-generator magazine.

Figure 54 — Population plan of the magazine in the lower plug-in unit (parabolic multiplier).

[Page 66]

8.4 Fault-Diagnosis Table

The following table lists observed fault symptoms (with the instrument switched on), the probable causes, and the recommended corrective measures. References to test procedures refer to the check-list and measurement steps described in Section 8.2.

No.	Fault symptom	Probable cause	Remedy
1	”Mains” button does not illuminate; computer is in no operating mode and is not functionally ready. Fuse for 25 V is absent.	Fuse for 25 V blown.	Replace fuse (see Section 8.3.2).
1b	”Mains” button does not illuminate; computer is in no operating mode and is not functionally ready. Fuse for 25 V is present.	Other fault.	Voltage check with test strip and measurement assembly.
2	”Mains” button illuminates; computer is in no operating mode and is not functionally ready. Fuse for 25 V is present.	Fault in 25 V supply.	Voltage check per Section 8.2.2.
2b	All overload lamps extinguish.	Fault in 400 Hz supply.	Proceed per Section 8.2.2.
3	—	—	—
4	—	—	—
5	No curve can be produced with the function generator.	Fault in potentiometer field or function generator per Section 8.1.6.	Plug-in card FG 2B in the negative-side section of plug-in card FG 2A.
5b	—	Amplifiers not operating.	—
6	The polygon generator for the potentiometer “10n” in the ordinate direction is not working.	Fault in 400 Hz supply to plug-in unit GE 1A or 400 Hz amplifier.	Plug-in card (GE 1A or 400 Hz amplifier).
13	Individual pushbutton does not respond when pressed.	—	—
14	”Exit” button does not illuminate when pressed.	—	Not possible.
—	“Mains” button illuminates; computer is fully operational in the remaining operating and functional modes. Fuse for 25 V: in no operating mode.	—	—

[Note: The remainder of page 66 consists of the fault-diagnosis table continuation, which is partially illegible in the source document due to OCR degradation of the original. The table format and symptom/cause/remedy columns continue for additional fault cases relating to operating voltages, amplifier function, and peripheral hardware.]