English translation
EAI Electronic Associates GmbH Newsletter — Bulletin No. 008, July–August 1966
This is an English translation of the original German document: EAI Electronic Associates GmbH, Mitteilungsblatt Nr. 008, Juli–August 1966.
ANALOG COMPUTER COURSES
Dates:
- 10–14 October 1966
- 7–11 November 1966
Each course runs Monday through Friday at the Astoria Hotel, Bad Aachen, 1966.
EAI cordially invites participation in one of the above-named analog computer courses. The courses take place at the Hotel Astoria in Aachen and last one week each.
The topics covered are outlined by the following points:
Linear computing components: Potentiometers, amplifiers
Nonlinear computing components: Multipliers, fixed function generators, variable function generators, various circuit variations, resolvers
Special computing circuits and components: Diodes, comparators, time-delay generators; Introduction to programming technique, scaling; Introductory examples and exercises on ordinary linear differential equations
Control engineering problems, delay circuits, transfer functions, solution of algebraic equation systems, partial differential equations; Examples and exercises on scaling technique and simple nonlinear problems
Fundamentals of iterative computing technique with simple examples; Application of iterative computing; Examples and exercises on iterative computing
Fundamentals of hybrid computing technique; The Digital Supplementary System DES-30
For non-EAI customers, a course fee of DM 150 is charged. For EAI customers, participation is free of charge, though the maximum number of fee-exempt participants is reserved at EAI’s discretion.
Anyone interested in attending — either personally or sending a staff member — is requested to submit a registration as soon as possible. EAI will endeavor to limit the number of participants per course to 30 persons. Seat reservations are allocated in order of registration receipt. Hotel reservations can be arranged upon request.
EAI SYMPOSIUM MUNICH — June 1966
In June, EAI held a symposium in Munich with the following presentations:
Wednesday, 22 June 1966
9:00–12:00 — Presentation A “Structure and mode of operation of the EAI Analog Computer, Type TR-48/58, and the Digital Extension Unit, Type DES-30” (Dipl.-Ing. K. Hartenbach, EAI Aachen)
14:00–17:00 — Presentation B “Application of the modern high-speed analog computer”
- Organisation of modern analog computers (operating control, parallel logic, etc.)
- Analog subroutine technique
- Multi-speed technique (with demonstration on the EAI computer system TR-48/DES-30) (Dipl.-Ing. C. Willems, EAI Brussels)
Thursday, 23 June 1966
9:00–12:00 — Presentation C “Coupling of analog computers with digital computers” “Programming problems in hybrid computing” (Dipl.-Ing. W. Bub, EAI Brussels)
14:00–17:00 — Presentation D “Modern EAI Analog and Hybrid Computers” “The Hybrid Analog Computer EAI 680” “The Hybrid Analog Computer EAI 8800. Outlook on the hybrid system EAI 8900, consisting of analog computer EAI 8810 and digital computer EAI 8400.” (H. H. Brüggemann, EAI Brussels)
Friday, 24 June 1966
9:00–12:00 — Presentation E “Determination of optimal control of a lunar landing vehicle. Example of the application of hybrid technique.” (Dipl.-Ing. W. Bub, EAI Brussels)
The great interest this symposium attracted in the southern German region has prompted EAI to organise further EAI Symposia in the Cologne–Aachen area, the Rhine–Main region, and northern Germany in November and December 1966.
NEW EAI PUBLICATIONS
The following new EAI brochures are available upon request:
- “EAI — Fully Transistorised Analog Computer PACE TR-48/58 and Digital Extension Unit DES-30” — AC 65103
- “EAI — Precision Polystyrene Capacitors” — IC 628T-2
- “EAI — X-Y Recorder VARIPLOTTER, Type 1110” — AP 6300-1
- “EAI — X-Y Recorder VARIPLOTTER, Type 1120” — AP 6641
- “EAI — Four-Channel Recorder”
SIX NEW X-Y RECORDERS FROM EAI — THE VARIPLOTTER SERIES
Six new X-Y recorders from EAI will be presented at the Western Electronic Show and Convention (WESCON) on 23–26 August 1966 in Los Angeles, California.
The VARIPLOTTER series comprises a complete range of recorders. The writing-area dimensions conform to DIN A4 and DIN A3 paper formats. All units are transistorised and feature a Zener-diode-regulated reference system, leak-proof plug-in ink cartridges, and direct drive for each axis. Accuracy is 0.1% static, 0.2% dynamic; reproducibility is 0.05%.
VARIPLOTTER 1120 and 1130 feature as a special characteristic a direct drive via a 3 mm wide steel band. This band, together with the ball-bearing system, eliminates all backlash and replaces the complicated constructions of pulleys and cable runs found in some other recorders. Both units accept DC voltage inputs with 18 calibrated ranges from 0.5 mV/cm to 10 V/cm. The scale factor is also continuously variable; a time base with six calibrated ranges is built in.
VARIPLOTTER 1120 has a square writing area of 25 × 25 cm and offers the advantage of using the same scale factor for both axes. It is also possible to use DIN A4 sheets. A built-in time base, 18 calibrated DC voltage ranges from 0.25 mV/cm to 10 V/cm, continuously variable scale factor, control of time deflection, and zero suppression over the full writing area are standard.
VARIPLOTTER 1131 has two pens and a writing area for DIN A3 format. It has three separate, independent inputs with range selection from 0.5 mV/cm to 10 V/cm for all three axes, plus a built-in time base acting on the X axis. It is used wherever two variables are to be plotted against a third.
VARIPLOTTER 1132 is a high-quality recorder for DIN A3 format, offered at a price previously associated only with smaller units. It has a single input range per axis, with the scale factor specified by the customer. Maximum sensitivity is 0.5 mV/cm. Connections for remote pen control, 1 MΩ input impedance, and zero-point adjustment are standard.
VARIPLOTTER 1133 is a DIN A3 recorder designed for applications where expensive extras are not needed but flexibility and versatility are required. It features 10 calibrated ranges per axis with sensitivity down to 0.25 mV/cm. Novel is the scale-factor setting via pushbuttons.
NEW COMPUTING AMPLIFIERS — SERIES 6.681, COMPACT CONSTRUCTION
The EAI amplifiers of the Series 6.681 are universally applicable computing amplifiers distinguished by a modern design that enables their use in a wide variety of laboratory and industrial applications, particularly in measurement technology and process control and monitoring.
1. Construction and Technical Characteristics
The amplifiers are built in three stages. The input stage is a push-pull circuit of selected transistor pairs. Careful component selection and circuit dimensioning achieve very favourable drift characteristics and small zero-point fluctuation. The operating point of the transistors is stabilised by current feedback, thereby largely reducing the influence of temperature and supply-voltage variations. In this way a very small drift voltage (between 50 and 500 µV) is achieved without the use of particularly costly chopper stabilisation.
Zero-point adjustment (balance) is carried out by a built-in potentiometer that shifts the potential in the collector circuit of the input stage. Zero-point stability does, however, depend on the external supply voltages (±15 V), which are used as reference potentials.
The second amplifier stage is a driver stage dimensioned so that the amplifiers can deliver an output current of at least 25 mA at ±10 V output swing. Because of its power gain, the computing amplifier also serves as a driver amplifier. This is particularly convenient for many laboratory and industrial tasks, as an additional power-amplification stage can then be omitted.
The output stage is an emitter-follower circuit that performs impedance transformation. The output impedance of the amplifiers is less than 50 mΩ (at 100 Hz).
In the 6.681 series, the Types 6.681-0 and 6.681-1 are three-terminal amplifiers, i.e. the input and output circuits are connected to ground. Types 6.681-2 and 6.681-3 have a differential input; their common-mode rejection ratio is at least 60 dB.
Types -0 and -1 versus -2 and -3 differ mainly in their drift characteristics. The “offset current” is used as the criterion for drift characteristics in the enclosed table. The offset current is the low-frequency component of noise that largely determines the drift properties of the amplifier. Because the drift of the output voltage depends on the feedback, the “offset current” is used as the meaningful drift criterion:
i_offset = e_offset / R_f
The 6.681 series amplifiers are encapsulated in epoxy-resin housings, and their modern design allows a space-saving construction with dimensions of 52 × 25 × 25 mm. Further technical characteristics and prices are contained in the enclosed table.
2. Applications
The Series 6.681 amplifiers are universally applicable as open-loop amplifiers; when suitable input or feedback networks are used, they function as:
- Summing amplifier: E_o = −(R_f / R_1) · E_1
- Difference amplifier: E_o = (R_f / R_1) · (E_2 − E_1)
- Inverter: E_o = −(R_f / R_1) · E_1
- Buffer (isolation amplifier): E_o = E_1
- Integrator: E_o = −(1 / R_1 C_f) · ∫E_1 dt
- Non-inverting amplifier: E_o = [(R_f + R_1) / R_1] · E_1
The high gain factor (greater than 80 dB) enables linearisation of the frequency characteristic with respect to amplitude and phase. The contacts provided on the housing allow convenient configuration of the open-loop amplifier as a computing amplifier with fixed gain, as an integrator, as a filter, and as an isolation element for the simulation of transfer functions.
Technical Specifications Table
| Parameter | Type 6.681-0 High-Speed Op-Amp | Type 6.681-1 High-Speed Op-Amp | Type 6.681-2 Differential DC Amp | Type 6.681-3 Differential DC Amp |
|---|---|---|---|---|
| Voltage Gain (f < 100 cps) | 98 dB typ, 93 dB min | 100 dB typ, 93 dB min | 86 dB typ, 80 dB min | 86 dB typ, 80 dB min |
| Unity Gain Cross-over | 24 MC typ, 20 MC min | 24 MC typ, 20 MC min | 1.2 MC typ, 1 MC min | 1 MC typ, 0.8 MC min |
| Full Power Response | 1 MC typ, 500 Kc min | 1 MC typ, 500 Kc min | 16 Kc typ, 12 Kc min | 13 Kc typ, 10 Kc min |
| Input Impedance, Differential (100 cps) | — | — | 150 K typ, 80 K min | 150 K typ, 80 K min |
| Common Mode Rejection (60 cps) | — | — | 68 dB typ, 60 dB min | 66 dB typ, 60 dB min |
| Input Offset Current | 10 nA typ, 30 nA max | 15 nA typ, 50 nA max | 20 nA typ, 35 nA max | 20 nA typ, 40 nA max |
| Input Offset Current Drift vs. Temp | 1.5 nA/°F typ, 3 nA/°F max | 1.5 nA/°F typ, 3 nA/°F max | 3 nA/°F typ, 5 nA/°F max | 3 nA/°F typ, 5 nA/°F max |
| Voltage Drift vs. Power Supply | 1.0 mV/V typ, 1.2 mV/V max | 1.0 mV/V typ, 1.2 mV/V max | 0.5 mV/V typ, 1 mV/V max | 0.5 mV/V typ, 1 mV/V max |
| Total Drift (per 8-hour period) | ±50 µV typ, ±100 µV max | ±300 µV typ, ±500 µV max | ±50 µV typ, ±100 µV max | ±300 µV typ, ±500 µV max |
| Total Output Drift (all sources, 10K inverter, 40°F–140°F) | ±10 µV/°F typ, ±30 µV/°F max | 3 mV typ, 6 mV max (full temp. range) | ±10 µV/°F typ, ±35 µV/°F max | 3 mV typ, 6 mV max (full temp. range) |
| Noise P-P | 1 mV typ, 1.5 mV max | 1 mV typ, 1.5 mV max | 50 µV typ, 100 µV max | 60 µV typ, 100 µV max |
| Output Voltage | ±11 V typ, ±10 V min | ±11 V typ, ±10 V min | ±11 V typ, ±10 V min | ±11 V typ, ±10 V min |
| Output Current | 25 mA min | 25 mA min | 25 mA min | 25 mA min |
| Output Impedance Inverter (100 cps) | 0.02 Ω typ, 0.05 Ω max | 0.02 Ω typ, 0.06 Ω max | 0.02 Ω typ, 0.05 Ω max | 0.02 Ω typ, 0.05 Ω max |
| Output Rise Time (10 V P-P, 10%–90%) | 0.2 µs typ, 0.5 µs max | 0.2 µs typ, 0.5 µs max | 8 µs typ, 10 µs max | 8 µs typ, 12 µs max |
| Capacitive Loading | 0.06 µF typ, 0.05 µF min | 0.05 µF typ, 0.03 µF min | 0.02 µF min | 0.02 µF min |
| Supply Voltage (nominal) | ±15 V | ±15 V | ±15 V | ±15 V |
| Supply Current (quiescent) | ±6 mA | ±6 mA | ±8 mA | ±8 mA |
| Price DM (ex Aachen, uncleared) | 485 | — | 434 | — |
| Price DM (ex Aachen, duty-paid) | 570 | — | 510 | — |
| Price DM (uncleared, reduced) | 357 | — | 332 | — |
| Price DM (duty-paid, reduced) | 420 | — | 390 | — |
CLASS-B ANALOG COMPUTERS WITH ACCESSORIES
EAI is currently in a position to offer the following analog computing systems as “Class-B” systems:
(Class-B units are those that have been used for some time in one of EAI’s computing centres in the USA or Europe and are offered at reduced prices under normal warranty and delivery conditions.)
Available:
- 1 unit EAI PACE Analog Computer, Type TR-48
- 1 unit EAI PACE Analog Computer, Type TR-20
EAI Electronic Associates GmbH · 51 Aachen · Bergdriesch 37 · Tel. (0241) 26021–26