Analog Computers

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RA 800 Miscellaneous Programming Notes — Fixed and Adjustable Function Modules

This file is an English translation of the original German document (ra800_misc.pdf) for the TELEFUNKEN RA 800 analog computer system.

Parabolic Multiplier Networks

The two parabolic multiplier networks are located in the jack field of the servo multiplier at jacks “+A” and “-A”, “+B” and “-B”, as well as “+C”, “-C”, “+D”, and “-D”. The network output is always present at the associated jack “SM”. The jack “X”, located to the left of jack “A”, must be connected to relay ground (jack in the black field with a brown cross-bar) when the reversing amplifiers insertable in plug-in unit NN 800 (accessible between “+A” and “-A” as well as “+C” and “-C”) are switched to the multiplier network for inverting an input variable.

Figure 4 shows the interconnection of a multiplier (A · B) with the necessary amplifier. The two “SM” jacks are connected in parallel via the multiplier network. One “SM” jack is connected to the summing point (jack “G”) of a freely selected amplifier configured as an open amplifier. This amplifier must be fed back from its output to a 10-input with a short-circuit plug (normalization to 20 kΩ) and additionally receive a feedback via a capacitor (capacitor plug) in the jack field between output and summing point (jack “S”). This capacitor plug is omitted if the computing amplifier RV 801 (HA2A + HI2A) is contained in the computer.

For sign-correct programming, the two input variables must be fed with the corresponding sign inversions via the reversing amplifiers in the plug-in unit NN 800 while the networks in fields A and C only require one polarity for programming. If the inputs of the multiplier are connected as shown in Figure 4 with correct sign, the product appears with correct sign at the output of the downstream amplifier. Since the freely chosen output amplifier can be selected at will, the display of the output voltage is performed at the digital voltmeter with the address of this amplifier (in the RA 900 HYBRID).

Special Note: The input variables for the multipliers must always be tapped from the outputs of computing amplifiers. To avoid errors due to differing loads, no potentiometer should be placed directly in front of the inputs.

3.2 Fixed Functions: sin x, sin πx, cos x, cos πx

(Card slot assignments: Figures 5, 6, 7, 8)

The networks located in fields “+A”/“-A” and “+B”/“-B” of the servo multiplier require the input variable X connected to jack “X”. Jack “X” (left of “A”) must be connected to relay ground (jack in the black field with a brown cross-bar). The two reversing amplifiers insertable in plug-in unit NN 800 and accessible between “+A” and “-A” as well as “+C” and “-C” are switched to two networks for inverting the input variable.

Figure 5 shows the circuit for the sin function. If the plug-in unit NN 800 contains the appropriate reversing amplifiers, only the networks lying in fields “B” and “D” need both polarities of the input variables. For the networks in fields A and B, one polarity suffices. If the inputs are connected with correct sign, the function appears with correct sign at the output of the downstream amplifier.

Function: 2 log₁₀₀ X (log₁₀₀ X)

(Card slot assignment: Figure 10)

(See Figures 14, 15 for circuit configurations with R₀ = 100 kΩ and R₀ = 200 kΩ)

4. Operation

4.1 Calibration

To ensure high computing accuracy, the summing-point drift of the amplifiers in plug-in unit NN 800 must be recalibrated from time to time. Calibration proceeds as follows:

  1. Press the “Null” test key on the computer’s operating panel.
  2. Select “Z 29”.
  3. Connect jack “Z 29” of the amplifier in the programming field of the NN 800 plug-in (accessible at jacks “-A” and “-C” in the jack field) with the output of the amplifier to be calibrated in the associated jack field.
  4. Using the adjustment controller on the plug-in (next to the overload lamps), set the amplifier to null. The display appears on the null instrument of the operating panel.

All other inputs and outputs of the amplifiers can remain programmed during calibration. After calibration the plug-in is ready for operation.

4.2 Multiplier

  1. Fit the plug-in as in Figure 2 with plug-in units.
  2. Insert the plug-in into the computer.
  3. Route the connection cables from the plug-in to the desired jack field of the computer per Figures 1 and 3.
  4. In the programming field of the corresponding jack field, connect jack “X” to relay ground (jack in the black field with brown cross-bar).
  5. Switch the first positive input variable coming from an amplifier output to jack “+A”.
  6. Switch the second positive input variable coming from another amplifier output to jack “+B”.
  7. Also feed the second input variable via a reversing amplifier to jack “-B”.
  8. Connect one output jack “SM” to the summing point (jack “G”) of an open amplifier in the computer.
  9. Feed the output of this open amplifier back to one of its 10-inputs.
  10. Further connect the amplifier output to its summing point (jack “S”) via a capacitor plug (330 pF).

The computation result appears with correct sign at the amplifier output when programmed as in Figure 4. By selecting the output amplifier, the output value appears on the digital voltmeter with the address of the amplifier.

4.3 −sin π X

  1. Fit plug-in as in Figure 5.
  2. Insert plug-in into computer.
  3. Connect plug-in to computer with cables.
  4. In the programming field connect jack “X” to relay ground.
  5. Switch a positive input variable coming from an amplifier output to jack “+A”, or switch a positive input variable coming from an amplifier output to jack “+B” and simultaneously, after polarity inversion, to jack “-B”.
  6. Connect the upper jack in the SM field (belonging to input field A or C) or the lower jack in the SM field (belonging to input field B or D) to the summing point (jack G) of an open amplifier in the computer.
  7. Feed the output of this open amplifier back to one of its 10-inputs.
  8. Further connect the amplifier output to its summing point (jack S) via a capacitor plug (330 pF).

The computation result appears with correct sign at the respective amplifier output when programmed as in Figure 9.

4.4 +cos π X

  1. Fit plug-in as in Figure 7.
  2. Insert plug-in into computer.
  3. Connect plug-in to computer with cables.

The programming is the same as described under 4.3; the circuit corresponds to Figure 9.

4.5 +sin π X

  1. Fit plug-in as in Figure 6.
  2. Insert plug-in into computer.
  3. Connect plug-in to computer with cables.

The programming is the same as described under 4.3; the circuit corresponds to Figure 9.

4.6 ±cos π X

  1. Fit plug-in as in Figure 8.
  2. Insert plug-in into computer.
  3. Connect plug-in to computer with cables.

The programming is the same as described under 4.3; the circuit corresponds to Figure 9.

4.7 log₁₀₀ X

  1. Fit plug-in as in Figure 10.
  2. Insert plug-in into computer.
  3. Route connection cables from plug-in to the desired jack field of the computer.
  4. Apply the positive input variable coming from an amplifier output to jack “+B” in the amplifier’s jack field.
  5. Connect the associated upper summing-point jack “SM” of the jack field to the summing point (jack “G”) of an open amplifier in the computer.
  6. Feed the output of this open amplifier back to one of its 10-inputs.
  7. Further connect this amplifier output to its summing point (jack S) via a capacitor plug (330 pF).

At the amplifier output the function −(1/2) log₁₀₀ X appears. Independently and simultaneously, the function +(1/2) log₁₀₀ X can be generated:

  1. Apply the negative input voltage coming from an amplifier output to jack “-B” in the amplifier’s jack field.
  2. Connect the associated lower summing-point jack “SM” of the jack field to the summing point (jack G) of an open amplifier in the computer.
  3. As in step 4.7.6.
  4. As in step 4.7.7.

At the amplifier output the function +(1/2) log₁₀₀ X appears. See Figure 11 for the circuit.

4.8 Adjustable Function F(+X)

  1. Fit plug-in as in Figure 12 with plug-in units.
  2. Insert plug-in into computer.
  3. Route connection cables from plug-in to the desired jack field of the computer.
  4. In the programming field, connect jack “X” to relay ground.
  5. Switch a positive input variable coming from an amplifier output to jack “+A”.
  6. Apply a further positive input variable X2 (possibly from the output of a second amplifier) to jack “+B”.
  7. Feed this variable also via a reversing amplifier to jack “-B”.
  8. Connect the output jacks “SM” (upper jack for input field A or C, lower jack for input field B or D) each to the summing point of a summator.

At the output of the first downstream summator (upper SM jack) the function F(+X1) appears, and at the output of the second downstream summator (lower SM jack) the function F(+X2). If both functions are to be added, the “SM” output jacks are short-circuited; at the output of one connected summator the sum of both functions then appears (see Figure 15).

4.9 Adjustable Function F(−X)

  1. Fit plug-in as in Figure 13.
  2. Insert plug-in into computer.
  3. Connect plug-in to computer with loose cables.

The programming is the same as described under 4.8.

[Translation covers the first 10 pages (the complete document); no additional content was deferred.]