Bedienungsanleitung: Analogrechner EA-22

Complete English translation of the original German-language document (19 pages).

Operating Manual

GTE

Analog Computer EA-22

Dipl.-Ing. H.O. Goldmann Techn. Elektronik 79 Ulm/Donau

Operating Manual

Transistor Direct-Analog Computer EA-22

Table of Contents Page

Concept and Scope of Delivery 1
Control Unit ZG-22 2
- 2.1 Switching on the Computer 2
- 2.2 Operating Modes 2
- 2.3 Measuring Instrument and Reference Potentiometer 3
- 2.4 Pen Drives 3
- 2.5 Central Overrange Indicator 3
- 2.6 Selector Switch AS-22
Timer ZG-22 4
- 3.1 Computation Modes 4
- 3.2 Computation Time 5
Selector Switch AS-22 6
Parallel Connection of Computers 6
Computing Amplifier Magazine and Overrange Indicator Panel 7
- 6.1 Zero-Point Adjustment of Computing Amplifiers 7
Passive Computing Elements and Potentiometer Panel 8
- 7.1 Patch Panel 8
- 7.2 Operational Unit ZS-A/S 9
- 7.2.1 Integrator Storage Circuit 9
- 7.2.2 Operational Unit PMS-A/S (see continuation)
- 7.3 Operational Unit ZS-A/S 10
- 7.4 Operational Unit FG-A/B, Function Generator–Summing Network 11
- 7.4.1 Function Setting 11
- 7.5 Operational Unit KS-A/B, Dual Comparator–Summing Network 12
- 7.6 Potentiometer Unit P-4 13
- 7.6.1 Potentiometer Setting 14
Control Unit ZG-22 14

Operating Manual

Transistor Direct-Analog Computer EA-22

1. Concept and Scope of Delivery

The concept of the transistor direct-analog computer EA-22 offers great flexibility in the design and practical application of multiple computing operational units. The program of active and passive computing elements is arranged in this concept in such a way that by far the greater number of problems can be dealt with in simulation. The passive computing elements are supported, in the case of the more complex types of operational units, by such assemblies that also quite extreme problems can be handled. In this way, starting from a basic configuration and building up, the computer can be extended to any desired scale, and in each case to the solution of any given problem. The current computational operational units available are listed in the Scope of Delivery for the computer.

A complete computer configuration consists of 20 computing amplifiers (5 Integrators and 10 Potentiometers and 5 Summers), along with 10 Operational Units. The needed computing elements and Operational Units are then available for the operator.

2. Control Unit ZG-22

The control unit serves the purpose of controlling the operating modes, the display of potentiometer and function-generator settings, the reading of computer variable values, and providing the reference voltages for the operator.

The control unit also contains the patch panel used as the reference panel for the operator.

2.1 Switching on the Computer

Before switching on the mains switch, the “Eigen” (self-control) key and the “Anfangswert” (initial condition) key are pressed in the control unit. After the mains switch is turned on, the overrange indicators light up on the display and go dark again within a few seconds. The computer is now operational.

If an overrange lamp remains lit, it indicates a faulty programming or a defect in the relevant amplifier or the associated operational unit.

2.2 Operating Modes

The operating modes are controlled by a key panel with the keys “Anfangswert” (initial condition), “Rechnen” (compute), “Halten” (hold), and “Pot.” (potentiometer set).

Anfangswert (Initial Condition): In the Anfangswert operating mode, the integrators are at their initial values. This operating mode is used as the rest or pause state, for example for programming or for zero-offset adjustment of the amplifiers.

Rechnen (Compute): In connection with the precision timer ZG-22, which serves for automatic control of the computer, the compute mode is initiated in the timer by pressing the “Rechnen” key. On the key panel, the current momentary operating mode is displayed, independently of which key is pressed. Without the timer, the continuous-computing mode can be switched on using the “Rechnen” key.

Halten (Hold): Using the “Halten” (Hold) key, the computing process can be interrupted, while the amplitude values are frozen. To continue the computing process, the “Rechnen” key must be pressed again; to start a new computation, the “Anfangswert” key must first be pressed.

Pot. (Potentiometer Set): A special key “Pot.” (Potentiometer Set) is used for setting coefficient potentiometers and function generators. In this operating mode, the summing junctions of all operational units are automatically driven to the loaded-potentiometer state, so that the potentiometers loaded into the circuit can be set (see Potentiometer Setting).

2.3 Measuring Instrument and Reference Potentiometer

The built-in measuring instrument serves the following measurements:

a) Checking the reference voltages ±10 V and the supply voltages ±15 V. The instrument is internally grounded for this measurement, and the measuring socket M is disconnected.

b) Measuring amplifier output voltages (computing variables) via the measuring socket M (or DVM at selector switch AS-22) in two ranges, ±5 V and ±1.5 V. The instrument is internally grounded for this measurement. The calibration of the two measurement ranges is performed via two potentiometers (P1 and P2) on the rear of the control unit. The reference voltage is used for calibration.

c) Compensation measurements in bridge configuration with 0.1% accuracy for potentiometer and function-generator setting. The built-in precision input potentiometer serves as the reference comparison potentiometer. The polarity of the reference voltage can be reversed. The instrument is in series with the wiper of the reference potentiometer. The sensitivity of the measuring instrument in compensation mode is approximately 7.5 mV/div.

In the “Pot.” operating mode, the measuring socket M is disconnected, and the instrument is connected to an internal measurement line (m) (for potentiometer and function-generator setting only). In all other operating modes, the variable to be measured can be applied to the instrument via the measuring socket M.

In all cases, however, an even greater accuracy requirement can be met by connecting a digital voltmeter at socket DVM.

2.4 Pen Drives

The pen drives serve the spring-loaded control of a two-coordinate plotter. They are short-circuited as long as the “Rechnen” key is pressed.

2.5 Central Overrange Indicator

A central overrange indicator lamp illuminates in the control unit whenever a computing amplifier goes into overrange.

During “Rechnen” and “Halten,” the central indicator is latched so that even brief overrange conditions are not missed. In the

“Anfangswert” operating mode, the lamp extinguishes after the overrange condition is cleared.

When the “U-Halt” (overrange halt) key is pressed, any overrange in the computer causes it to switch automatically to the “Halten” operating mode and remain there, so that amplitude ratios can be examined under overrange conditions.

To localize an overrange amplifier, the lamps on the overrange indicator panel of the computer serve the purpose. The overrange of each individual amplifier is displayed on the overrange indicator panel. In parallel operation of multiple computers, the overrange of any computer in the overall system is shown at all computers.

3. Timer ZG-22

3.1 Computation Modes

The precision timer serves for automatic control of the computer. A selector switch determines the computation mode, which is initiated in the control unit when the “Rechnen” key is pressed.

Continuous Computing (Dauer-Rechnen): In the “Dauer-Rechnen” (Continuous Computing) position of the selector switch, the timer has no function. The two computing amplifiers No. 11a and No. 11b required for certain computing modes as inverters are available at the edges of the programming panel.

The automatic computing modes are:

Repetitive Computing (Repetierendes Rechnen): The integrators cycle periodically through the “Anfangswert” and “Rechnen” operating modes.

Iterative Computing (Iterierendes Rechnen): A cycle of “Anfangswert” – “Rechnen” – “Halten” is continuously repeated by the timer. A special integrator-storage circuit is available, which can store the computed values during the hold period and carry them as initial conditions into the subsequent “Anfangswert” and compute period. This enables the transfer of computed results from one cycle to the next. (See Integrator Storage Circuit.)

Computing with Halt (Rechnen mit Halt): After the set computation time has elapsed, the computer automatically switches to the “Halten” (Hold) operating mode. The sawtooth voltage of the timer reverts to the initial-condition level.

Values can be read and program changes made. By pressing the “Weiter” (Continue) key, the same or the newly set time interval is continued.

3.2 Computation Time

For the automatic computation modes, the computation time can be set in three decades. The initial-condition and hold times are fixed. The following combinations are possible:

Computation Time	0.1 … 10 sec	1 … 100 sec
In steps of	0.1 sec	1 sec
IC and Hold Time	0.1 sec	1 sec

Accuracy of computation time: 0.1% ± 1.5 ms.

For the exact initial-condition acquisition at the integrators (at C = 5 nF), the long initial-condition period must be used. This also allows, during repetitive and iterative computing, the recovery of amplifiers oversteered during the computation period. The calibration of the initial-condition and hold times is performed via four potentiometers (P1 to P4) on the rear of the timer.

For a continuous adjustment of the computation time, a potentiometer can be inserted in the timer at socket 1 at the input (green with green), and socket 2 at the output (orange with orange) of this potentiometer connected (the potentiometer full-scale point is calibrated). In normal operation socket 1 is connected to socket 2 by a short-circuit plug.

A precisely linear sawtooth voltage, corresponding to the set computation time and spanning the range −10 V to +10 V, is available at a front-panel socket for use with an oscilloscope as a time base. It is loadable to 10 mA.

A front-panel socket can also supply a voltage for the time axis of an oscilloscope. At this socket, the voltage in the “Pot.” and “Anfangswert” modes is −25 V (relay supply voltage), and in the “Rechnen” and “Halten” modes it is zero volts.

4. Selector Switch AS-22

With the selector switch, the outputs of all computing amplifiers can be selected, and then either read via the measuring socket M at the measuring instrument in the control unit or measured via the DVM socket by connecting a digital voltmeter. (See Control Unit.)

5. Parallel Connection of Computers

For problems of larger scope, several EA-22 computers can be connected in parallel. Control of the overall system can be taken over by any one computer, which then also supplies the reference voltage and the timing for the automatic computing modes.

On the rear of the computer there are two identical pairs of parallel connectors St 1 and St 2. To connect a second computer in parallel, connector St 1 of the neighboring computer is connected to parallel connector St 1 of the first computer via a parallel cable (St 1). Two further sockets on the rear of the neighbor computer establish the connections to the zero-point potentiometers (right-side socket) and to the overrange relay (left-side socket) of the overrange indicator panel. The same applies for St 2.

The parallel connector St 1 serves for control of the neighboring computer. Via the parallel connector St 1, the 20 numbered parallel switching sockets of the neighboring computer are connected with the patch panel sockets of the master computer. Thus 20 parallel patch lines are available for programming purposes.

Only on the computer that is to take over control of the overall system is the “Eigen” (Self-Control) key pressed. The position of the other keys on the slave computers is of no consequence. The current operating mode is, however, visible on the key panels of all computers. An overrange in the overall system is likewise displayed on the central overrange indicators of all slave computers in parallel. Independent operation of a single computer is only possible when the parallel cable St 1 is removed.

In parallel-connected computers, small differential voltages between the ground potentials of the individual computers can arise due to the ground currents of the mains cables. In such cases, only one of the computers should be provided with a protective-earth mains cable. The shared ground connections in any case form a protective-earth connection.

6. Computing Amplifier Magazine and Overrange Indicator Panel

The computing amplifiers are plug-in modules contained in a card magazine in the rear portion of the computer, which becomes accessible after removal of the upper rear cover. Located beneath the magazine are the amplifier cards. Each card in the magazine contains two computing amplifiers.

Viewed from the rear, the rightmost card in the magazine belongs to operational unit No. 1a (see numbering on the patch panel), the next-to-right amplifier belongs to operational unit No. 1b, and so on. The two leftmost amplifiers in the magazine are amplifiers No. 11a and No. 11b (see Timer). Changing of amplifier cards and operational units is carried out from the rear.

The supply voltages for the amplifiers are supplied by plug-in cables lying on the right side of the magazine (from the mains-power socket St 1). Via two further sockets on the amplifier cards, connections are made to the zero-point potentiometers (right-side socket) and to the overrange relay of the overrange indicator panel (left-side socket). To swap amplifier cards, the connectors must be detached from the mains (remove mains connector). To access the overrange indicator panel from the rear, the entire rear lower control-unit insert must be slid out approximately 5 cm from the rear after loosening four screws.

6.1 Zero-Point Adjustment of Computing Amplifiers

For zero-point checking and zero-point adjustment, individual amplifier outputs are selected via the selector switch AS-22 and connected via the measuring socket M to the measuring instrument in the control unit. The instrument is connected to the compensation circuit, and the compensation potentiometer and reference potentiometer are set to zero. Zero-point correction is made via the associated zero-point potentiometer on the overrange indicator panel. To amplify the measuring voltage, a tenfold amplifying summing amplifier may additionally be connected in series. If this is available, connection of a DC micro-voltmeter is recommended.

The amplifiers are placed in the “Anfangswert” (Initial Condition) operating mode for zero-point adjustment. An integrator in this operating mode—unlike a summing amplifier—measures its own zero-point error with feedback closed (computing mode). The zero-point error of a summing amplifier can also be measured in “Rechnen” (Compute) mode, but initial- and compute-mode inputs must be disconnected.

7. Passive Computing Elements and Potentiometer Panel

The passive computing elements can be connected via patch sockets on the programming panel of the computer. On the patch panel, in addition to the amplifier inputs and outputs, the connections to the zero-point potentiometers and to the overrange relay of the overrange indicator panel are also established. Changes of amplifier cards and operational units are made from the rear.

The supply voltages for the amplifiers are delivered via a plug-in cable lying on the right side of the magazine (from the mains-connector socket St 1). Via two further sockets on the amplifier cards, the connections to the zero-point potentiometers (right socket) and the overrange relay of the overrange indicator panel (left socket) are established. To swap amplifier cards, the connectors from the mains must be removed (remove mains connector). To access the overrange indicator panel from the rear, the entire rear lower control-unit insert must be slid out approximately 5 cm from the rear after loosening four screws.

7.1 Patch Panel

The patch panel of the computer serves as the central interconnection point from which all computing and programming work is performed. The patch panel is located in the front of the computer.

The patch sockets on the programming panel have the following color coding:

pink: Inputs for amplifiers, potentiometers (i)
orange: Outputs for amplifiers, summing junctions (o)
red: Reference voltages ±10 V
ochre: Reference voltage (null)
white: Control lines, parallel switching lines, timer signals
green: Ground (null)

7.2 Operational Unit ZS-A/S, Dual Summer–Integrator Network

The computing amplifiers are used for integrating or summing depending on the patch connections. Using a double patch plug on the front panel, each amplifier can be used as a multiplier, summer, or as a straight-through amplifier.

Summer: Socket with amplifier symbol — connect using double patch plugs to the sockets of the summing network below.

Integrator: Socket with amplifier symbol — connect using double patch plugs to the sockets of the integrating network below. Connect socket M with socket R via a single patch plug.

Per network there are four inputs with weighting factors 1, 1, 10, 10, and one input A for the integrator–for amplification. One input ∞ enables connection of additional input resistors for non-linear networks.

The summing capacitors can be switched in ratios 10:1 from 5 nF to 0.5 nF per integrator individually, which allows the time constant to be varied over a wide range (0.0…0.1 sec). For an integration weighting factor of 1 and for 0.5 nF, the weighting factor becomes 10.

The activation of the relay is generally accomplished via the central control lines p, r, and h. Bild 2 shows in tabular form the activation states of the control lines for the individual operating modes.

The relays (computing relay H, hold relay) of the integrators for the “Anfangswert,” “Rechnen,” and “Halten” operating modes can also be activated externally via the sockets R and H on the front panel. This is possible, alongside normal control from the control unit, also for the purpose of constructing step-function generators, analog memories, and other special circuits.

7.2.1 Integrator Storage Circuit

The integrator storage circuit for iterative computing, Bild 3, allows values computed during one cycle to be carried over into the following cycle. The charging of the storage integrator takes place in the “Halten” mode. Its computing relay R is activated only when the “Anfangswert” key is pressed (for acquisition of the initial condition at the start of computation), and its hold relay H is activated via the activation line a, both of which are present at the patch panel.

Activation line p: activated only at pressed “Anfangswert” key, for acquisition of initial conditions at the start of computation.

Activation line a: activated only in the “Halten” operating mode.

7.3 Operational Unit PMS-A/S, Dual Multiplier–Summing Network

The operational unit PMS contains two complete multiplier and summing networks, which, in combination with two computing amplifiers, perform the mathematical operations of multiplication, division, square rooting, and summation.

The amplifier inputs and outputs of the unit are accessed via a connector on the rear. By simply reversing a double patch plug, each amplifier can be used as a multiplier, summer, or straight-through amplifier.

Summer: Socket with amplifier symbol — connect using double patch plug to the sockets of the summing network below.

Multiplier: Socket with amplifier symbol — connect using double patch plug to the sockets of the multiplier network below.

Per network four inputs with weighting factors 1, 1, 10, 10 are available. A fifth input resistor serves for feedback.

For multiplication, the quantities X and Y must both be available with both signs. At the amplifier output, the product is then (with 20 kOhm feedback) Z = +X·Y/10 V, or Z = −X·Y/10 V. By exchanging +X and −X or +Y and −Y.

Since the multiplying network is normalized to a feedback resistor of 20 kOhm, an additional summation must be performed for multiplication (connect socket 0 with socket S). In this case, however, the weighting factors of the summing network are multiplied by 0.1, because those networks have a feedback resistance of 200 kOhm.

For division and square rooting, the multiplier network is placed directly in the feedback of the computing amplifier, so that no additional amplifier is required for these operations (Bild 4 and Bild 5).

If the unit itself cannot sum, the summing networks serve as input networks for other amplifiers.

7.4 Operational Unit FG-A/B, Function Generator–Summing Network

The operational unit FG contains a variable function generator network with 20 temperature-compensated diode segments and two summing networks. In conjunction with two computing amplifiers, whose inputs and outputs are accessed via a connector on the rear, the operational unit realizes a variable function generator or two summers.

The switching is effected by two double patch plugs on the front panel.

Summer: Socket with amplifier symbol — connect using double patch plug to the sockets of the summing network below.

Function Generator: Socket with amplifier symbol — connect using double patch plug to the sockets of the function generator network below.

Per network four inputs with weighting factors 1, 1, 10, 10 are available. A fifth input resistor serves for feedback. If the summing network is not used, it serves as an input network for other amplifiers.

For the function generator, only one input +X is required, at which the left computing amplifier output is applied, which generates the function F(X) in all four quadrants. The second amplifier (right Verstärker) is not needed and provides internal current inversion.

For a series of functions F(X) with special characteristic (e.g., x², x^(n+1), n=1, 2, …), the second amplifier is not needed and can be used as a summer.

The unit also contains two free silicon diodes for realization of special functions such as “Dead Zone,” “Carry,” etc. Seven front-panel sockets serve as a distribution point.

7.4.1 Function Setting

Since the breakpoints of the diode segments are at equidistant spacings of 1 Volt, only the slopes of the diode segments need to be varied for setting a function. This allows—in conjunction with the function-generator setting device FEG—

a rapid and convenient setting of the desired function. Variation of the slopes is accomplished by coarse and fine adjustment over a range of ±3.5 V/V. A variable parallel offset also enables representation of functions that do not pass through the coordinate origin.

To set a function, the function-generator operational unit together with the function-generator setting plug FEE is slid into the computer. The potentiometers on both sides of the unit are then set with a screwdriver to reproduce the desired connections via a double patch plug on the front panel. A clip holder on the function-generator setting plug allows the switching of the “general functions,” for which two amplifiers are required, to the “special functions,” for which only one amplifier is needed.

In the “Pot.” operating mode, the diode breakpoints of the function generator setting device FEG can be selected individually. The setting is accomplished from zero always in the positive direction to +10 V, and from zero in the negative direction to −10 V.

The breakpoint voltages can be measured with:

a) Measuring instrument in compensation circuit. The function generator output line is connected to the internal measurement line (m), which is connected to the measuring instrument compensation output.

b) Measuring instrument in ±15 V range, by connecting the DVM socket with the measuring socket M.

c) Digital voltmeter, connected to the DVM socket.

For some functions it is advisable to repeat the setting.

7.5 Operational Unit KS-A/B, Dual Comparator–Summing Network

The operational unit KS contains two comparator and two summing networks. The unit is connected to two computing amplifiers, whose inputs and outputs are accessed via a connector on the rear, for comparing computing voltages and for summation.

Summer: Double patch plug must cover the amplifier symbol.

Comparator: Double patch plug must cover the letter K.

Per network four inputs with weighting factors 1, 1, 10, 10 are available. A fifth input resistor serves for feedback.

In comparator switching, the amplifiers decide whether a (weighted) sum of at most five input quantities is positive or negative, and they activate a relay with two changeover contacts, which is displayed on the front panel.

The contact designated “a” is closed when connected to the overlying and the contact designated “e” is closed when connected to the underlying contacts, when the (weighted) sum of the input voltages is positive, respectively when the (weighted) sum of the input voltages is negative.

The required overrange protection for the amplifiers (Zener diodes) is embedded in the comparator network.

7.6 Potentiometer Unit P-4

The potentiometer unit P-4 contains four wire-wound precision potentiometers for precise setting of coefficient and initial values. Three potentiometers are internally grounded; the fourth (D) is insulated and free-running, and appears with two inputs on the front panel. It can also be accessed via a short-circuit plug on the front panel.

On the front panel there are also sockets for positive and negative reference voltage, which can be connected to the potentiometer inputs via short-circuit plugs.

All potentiometers are protected against overload via a resistor (wiper) at the output.

7.6.1 Potentiometer Setting

For correct setting and reading of the potentiometers, the timer serves the automatic control of the operating modes (7.1). In the “Pot.” operating mode, all operational units are automatically switched to the loaded potentiometer state, so that the potentiometers loaded into the circuit can be set and read. The “Pot.” operating mode is switched by pressing the key “Pot.” (see Operating Mode).

Setting and reading of the potentiometer value is accomplished by connecting the potentiometer output to the internal measurement line (m) on the front panel. In the measuring instrument compensation circuit, the correct value can be set and read out.

8. Control Unit ZG-22

The control unit is a component separate from the computer, which provides all operating voltages, reference voltages, the time base, and the control switching functions. The unit is connected on the rear to the computing amplifier module (St 1) and to the selector switch (St 2).

The operating voltages of the control unit have the following specifications:

Supply voltage (for Integrators)	±25 V / ±1 A
Supply voltage (for Summers/Amplifiers)	±15 V / 1.5 A
Reference voltage (stabilized)	±10 V / 1 A
400 Servo (for Summers)
Reference voltage	±10 V / ±2 A

The computing amplifier module is connected to the control unit via the computing amplifier magazine (St 1) and the selector switch (St 2).

[page 17: figure only]

Bild 1: Integrator–Summer–Integrator Circuit (Schaltung Integrator)

Bild 2: Activation of Control Lines

Operating Mode	p	r	h
Pot.	●
Anfangswert	●
Rechnen		●
Halten			●

● = line activated (Leitung gereizt)

[page 18: figure only]

Bild 3: Integrator Storage Circuit

Control line p: activated at pressed “Anfangswert” key. Control line a: activated in the “Halten” operating mode.

The page contains two circuit diagrams with brief captions and equations.

Fig. 4: Division Circuit

The upper circuit shows a division configuration using a multiplier network. An operational amplifier with feedback through a multiplier/divider network produces the output Z. The input signals are X (applied at the inverting input with a gain factor) and Y (applied to the multiplier network).

The governing equations are:

Z = X/Y ; Z·Y = X ; Y ≠ 0 (Y must not be zero)

Y must not equal zero.

Fig. 5: Square Root Circuit

The lower circuit shows a square root configuration. An operational amplifier with feedback through a multiplier/divider network produces the output Z. The input signal X is applied at the inverting input.

The governing equations are:

Z = √X ; Z² = X ; X ≥ 0

C* = Stabilization capacitor