Instruction Manual: Model 3103 Dual DC Amplifier (Chopper-Stabilized) and Model 3732 Electronic Multiplier (Quarter-Square Type)
August 1960
INSTRUCTION MANUAL
MODEL 3103
DUAL DC AMPLIFIER
(Chopper- Stabilized)
DONNER SCIENTIFIC COMPANY
Concord, California
A Division of
Systron-Donner Corporation
Lot No.
Model 3103
CONTENTS
General Description .
‘Specifications
Installation
Operation
Circuit Description .
Servicing
Tube Pin Voltages, (Table 1)
Parts List
Parts Location |Ilustration
Schematic Diagram, Drawing No. 5217
Page
10
SYSTRON €=—=3[5 > DONNER
cORPORATI ON
WARRANTY
Systron- Donner instruments are warranted during a period of one year from date of shipment to
original purchaser to be free from defects in material and workmanship. This warranty does not
apply to vacuum tubes, except as they are warranted by tube manufacturers. The liability of
Seller under this warranty is limited to replacing or repairing any instrument or component
thereof which is returned by Buyer at his expense during such period and which has not been
subjected to misuse, neglect, improper installations, repair, alteration, or accident. Seller
shall have the right of final determination as to the existence and cause of a defect. In no
event shall Seller be liable for collateral or consequential damages. This warranty is in lieu
of any other warranty, express, implied or statutory, and no agreement extending or modifying
it will be binding upon Seller unless in writing and signed by a duly authorized officer.
RECEIVING INSPECTION
Every Systron Donner instrument is carefully inspected and is in perfect working order at the
time of shipment. Each instrument should be checked as soon as received. If the unit is
damaged in any way or fails to operate, a claim should immediately be filed with the trans-
portation company.
REPAIRS
Whenever a Systron-Donner instrument requires service, the nearest Systron-Donner represen-
tative should be contacted; all representatives will provide immediate service or arrange
factory returns when necessary.
Please specify both model and serial number in all correspondence concerning Systron-Donner
instruments. Address all inquiries on operation or applications to your nearest sales represen-
tative or Sales Manager, Instruments, Systron-Donner Corporation, 888 Galindo Street, Concord,
California,
CONCORD, CALIFORNIA
ADDENDUM
REFERENCE: INSTRUCTION MANUAL MODEL 3103, PAGE 1, GENERAL DESCRIPTION
PARAGRAPH 2, WAS: " °*** The amplifiers are designed to withstand
prolonged overloads or excessive load currents eee!
CHANCE TO: "™ eee The amplifiers are designed to withstand
| momentary overloads or excessive load currents.
Prolonged direct shorts or overloads which
would cause the amplifier to deliver over 10ma
may cause permanent damage and amplifier failure eal
al
GENERAL DESCRIPTION
The Donner Dual DC Amplifier, Model 3103,
contains two identical amplifier channels con-
structed on a compact printed circuit chassis.
Each dual amplifier is a plug-in unit having a
special low-leakage male connector as an integral
part of the chassis. Model 3103 designates the
chopper-stabilized version of the amplifier. When
the stabilizing amplifier section is omitted, the
amplifier is designated Model 3104. The stabi-
lizing amplifier section consists of a two-stage
mechanical chopper-type a-c amplifier which im-
proves the d-c gain and drift characteristics of
the ‘basic amplifier section by a factor of better
than 500. /
/
The Model 3103 dual DC amplifiers have
been designed for use either with Donner analog
computers or in DC amplifier systems. Their high
gain, band width, and stability when operated
with complex feedback networks make them well-
suited for special applications. Stray capacity
up to 500 mmfd. may be connected to both the
amplifier input and output terminals with neg-
ligible effect upon the frequency response below
20 ke. Stability is maintained at low values of
feedback resistance, including a short circuit.
The amplifiers are designed to withstand pro-
longed overloads or excessive load currents.
The Model 3103 features a true overload
indicating output for external indicator circuitry.
SPECIFICATIONS
(Mode! 3103, Stabilized)
Note: Unless otherwise noted, all specifications
apply to a unity inverter
(R,,= Rg = 1 megohm)
TOTAL DC GAIN ->10 million
Unstabilized section —>20,000
Stabilizer —>500
OUTPUT
Type: A voltage 180° out of phase with the
input voltage. Maximum range — +100
volts at 4 ma maximum load current.
OUTPUT IMPEDANCE -— less than 0.01 ohm
D.C. STABILITY (referred to summing junction)
Short-term stability — +200 ,.v (random noise)
Off Set for +10% line voltage change — +150 pv
PHASE SHIFT
Frequency
A B_ | A: R,, & Re,= 100K
W=0.5° | Ske 3ke
1.5° | 10ke Ske
5.0° | 40kc 15ke
B: Ro & Rep = 1 megohm
Model 3103
FREQUENCY RESPONSE
A _B_ arg. & Ry = 100K
f 100kc | 45ke m
B:R, & Rey= 1 megohm
resonance
_INTEGRATOR DRIFT
(R = 1 megohm, C = 1 mfd)
Average drift is less than 150 pv/sec.
OVERLOAD RECOVERY TIME - less than 8 sec.
NOISE LEVEL
(60 cps hum referred to summing junction) —
2 mv peak-peak
POWER REQUIREMENTS (two channels)
+300 volts regulated at 25 ma (quiescent)
-310 unregulated at 19 ma (quiescent)
~150V regulated at 0.35 ma
6.3V +10%,' 50-60 cps at 2.0 amps
DIMENSIONS —. 3 inches height
1-7/8 inches width
8 inches length
INSTALLATION
MOUNTING
The Dual DC amplifier is the basic com-
ponent for one series of Donner analog computer
components and DC amplifier systems. In the
latter application, a Model 3121 amplifier re-
ceptacle unit is normally employed for mounting
up to five dual amplifiers. The amplifiers are
installed in the computer or receptacle unit by
unlocking the two wing nuts on the rear apron
and inserting the amplifier card into the recep-
tacle connectors. When the rear apron is closed
and locked, the amplifiers are held securely in
place by the rubber mounting guides on the apron.
All signal and power connections to the amplifier
are available for measurement at the terminals
of the mating female receptacle. Input and output
signal connections are available at the front panel
receptacles on standard mounting units.
POWER REQUIREMENTS
All filament and DC operating voltages for
the dual DC amplifier are normally supplied by
the compact regulated power supply contained
in the amplifier receptacle unit. Power require-
ments for one dual amplifier chassis (2 amplifier
channels) are given in the Specification section.
The +300 volt source is regulated to within +0.2%
for full line and load variations. The -150 volt
source is regulated to within +0.1%. Hum and
noise should be restricted to less than 50 milli-
volts peak-to-peak for best results. All drift and
offset characteristics given under ‘‘Specifica-
tions’’ were obtained with an unregulated fila-
ment supply (6.3 volts +10%). Regulation of this
supply to within 1% will considerably improve
amplifier stability.
BALANCE VOLTAGE
An external positive and negative bias
voltage source is connected to pins F and D of
the amplifier connector to provide the necessary
‘zero voltage’’ for balancing the amplifier. In a
standard Donner installation this circuitry is
provided in the amplifier receptacle unit.
OPERATION
WARM-UP
The Model 3103 amplifiers should be al-
lowed to warm up for at least 15 minutes prior
to their use in critical applications. When em-
ployed with instruments in which filament and
plate power supplies are separately controlled,
the plate power need not be energized until the
amplifiers are ready for use.
BALANCING
After an initial warmup period, the dual
amplifier should be checked for balance. When
used with a standard Donner receptacle unit or
computer, refer to the appropriate instruction
manual for the balance procedure.
Normally, the dual de amplifier is checked
in an inverting circuit having a gain of 1000 (With
reference to Figure 1,R;,, = Ik, Ry, = 1 megohms.)
With the Model 3104, use R;, = 10k, Ry, = Im.
The average output voltage reading in either case
should be set at zero by adjusting the external
balance potentiometer and should not in any case
exceed +0.4 volts, which reflects a typical off-
set voltage appearing at the summing junction of
the amplifier. The minute fluctuations of the
meter needle during the balance adjustment are
a normal condition.
OVERLOAD CONDITION
During operation of the Model 3103 amplifier
with Donner computers or the Model 3121 recep-
tacle unit, observe the overload indicators to
make certain that the amplifiers being used do
not overload. If an overload occurs, first verify
the external computing circuit connections, com-
ponent values, and range of input voltages. Next,
verify the balance adjustment. If the amplifier
appears to be defective, remove the chassis from
the receptacle unit. During the warm-up period,
all amplifiers may overload but they should re-
turn to normal after approximately one minute.
Place a feedback resistor between the input and
output terminals of any amplifier not being used
in a computing circuit to insure that it will not
drift into overload.
Model 3103
CIRCUIT DESCRIPTION
fb
Figure 1. Basic Operational Amplifier Circuit
DC amplifiers are used in analog computers
to perform the mathematical operations of addi-
tion, subtraction, integration, and multiplication
by a constant. These operations are performed
by associating precision resistors, capacitors,
and potentiometers with the basic DC amplifier.
When two precision resistors are connected to
the basic amplifier as illustrated in Fig. 1, de-
generative feedback is applied around the ampli-
fier, and the value of the closed loop gain is
precisely controlled by the ratio of the feedback
resistor, Rep, to the input resistor, Ria If the
amplifier gain is large relative to this resistor
ratio, then the value of the closed loop gain is
exclusively determined by the resistor ratio.
The junction between the input resistor
and the feedback resistor is called the amplifier
summing junction. The summing junction voltage
appearing at this point is equal to the amplifier
output voltage reduced by the amplifier gain. As
the amplifier gain is made very large, the voltage
at the amplifier summing junction is reduced to-
wards zero, and the amplifier summing junction
can be considered as a virtual ground. Since the
DC amplifier exhibits a large, but finite gain, a
very small voltage exists at the amplifier summing
junction. This voltage is, in fact, necessary to
generate the amplifier output voltage.
R
fb
STABILIZATION
When the voltage applied to the amplifier,
illustrated in Fig. 1, is equal to zero, the output
voltage should also be zero. However, the ampli-
fier tube characteristics, power supply voltages,
and the resistance values do not remain perfectly
stable with time. As a consequence, the DC
potentials within the amplifier circuitry will vary
as a function of tube aging, temperature, the DC
supply potentials, and the heater voltages applied
to the amplifier vacuum tubes. These effects
accumulate within the amplifier and generate an
error voltage at the amplifier output terminals.
In general, the degenerative feedback through the
resistive connection between the amplifier input
and output terminals greatly reduces the influence
of variations which arise within the amplifier
circuitry. The most significant source of drift
within the operational amplifier is associated with
the amplifier input stage(since this voltage under-
goes the largest amount of amplification through
succeeding stages) and, in particular, is caused
by variations in the heater potential of the input
tube. It has been shown that degenerative feed-
back is incapable of reducing the amplifier drift
which is caused by heater current variations in
the amplifier input stage.
In order to minimize the critical low tre-
quency components of drift within the amplifier
input stage, a drift-free stabilizing amplifier is
connected into the circuitry as illustrated in
Figure 2. The addition of this stage effectively
increases the overall amplifier gain at low fre-
quencies by a factor of approximately 500. Since
this stage contributes no drift of its own, the ef-
fective overall drift of the amplifier is thereby
reduced by approximately an equal amount.
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DC AND
DRIFT
Figure 2.
Model 3103
DC
AMPLIFIER
STABILIZING AMPLIFIER
DC Amplifier With Stabilization
CIRCUIT DESCRIPTION
LOW PASS
Oo “ CHOPPER
° 60 CPS
Figure 3.
AC
AMPLIFIER
DIODE
DEMODULATOR
60 CPS
© MODULATOR
SMOOTHING
FILTER
Es
MWh L cout
Simplified Diagram of Stabilizer Amplifier
(Designated Voltages refer to Figure 4.)
STABILIZING AMPLIFIER (Model 3103 only)
With reference to the appended amplifier
schematic diagram the stabilizer portion of the
circuit includes all components associated with
tubes V103 and V104. A simplified diagram of the
stabilizer amplifier is shown in Fig. 3. Typical
voltage waveforms at significant points within
this diagram are illustrated in Fig. 4. Circuit
symbols designated below refer to the ‘‘A’’ ampli-
fier channel.
A low frequency voltage applied to the amp-
lifier input terminal passes thru the RC filter
consisting of R110 and C102, which attenuates
frequencies above 3.0 cycles, thus allowing only
very low frequency components to pass to the
chopper from the input terminals.
The electro-mechanical chopper, Y101, al-
ternately grounds and ungrounds the amplifier in-
put voltage at the point between resistor R111
and capacitor C103 at a rate of 60 cps so that
the low frequency components of input voltage
are converted into a 60 cps square wave as shown
in Fig. 4B. Blocking capacitor C103 removes the
de component of the signal, producing the wave-
form shown in Fig. 4C. The type 12AX7 and 6112
dual triodes (% of V104 and 4 of V103) form a
typical two-stage capacitively-coupled amplifier.
The output of this amplifier is an amplified
squarewave voltage in phase with the signal
applied to the input grid of V104. This signal
is passed thru blocking capacitor C110 to the
diode demodulating circuit consisting of rectifiers
CR101 and CR102. The diode demodulator operates
in synchronism with the chopper modulator in
order to generate a rectified voltage (shown at
Fig. 4E) which is then applied to the grid (pin 2)
of the DC amplifier input stage V101 through the
RC filtering network formed by resistor R129 and
capacitor C104.
The diode demodulators function in the
following manner: The two silicon diodes, CR101
and CR102 are connected in series with the cur-
rent limiting resistors, R130 and R131 across
the center-tapped source of 6.3 volts a-c. During
one-half of the 60 cps period, the two diodes will
conduct heavily, causing the voltage at the junc-
tion between capacitor C110 and resistor R129
to be at the same level at the center tap of the
6.3 a-c filament power source; i.e., at zero po-
tential. During the second half of the 60 cps
period the two silicon diodes will be biased in
the non-conducting state and the voltage at the
junction between them will be unaffected by the
demodulator circuitry. The waveform of the volt-
age at the junction between the diodes is illus-
trated in Fig. 4D.
The stabilizing amplifier has a gain of 500
or better at zero frequency (d.c.). The low pass
RC input filter attenuates input signal frequencies
above 3 cps and the stabilizing amplifier is vir-
tually removed from the circuit at frequencies
substantially above 5 cps. The stabilizing amp-
lifier, therefore, is the normal path for d-c and
drift frequency components, while higher fre-
quencies are applied directly to the input tube
(V101 of the DC Amplifier).
Model 3103
+1 mv
INPUT VOLTAGE
0 (a)
+1 mv
MODULATED INPUT
7 ,
VOLTAGE [
(60 cps Modulation) 0) r , C7 = (b)
+0.5 mv
BLOCKED INPUT 0 | T— a (c)
VOLTAGE | = L—
-0.5 mv
oO | (d)
AMPLIFIED | lL
DEMODULATED INPUT
Ey,
-2 V
O | (e)
SMOOTHED OUTPUT
Figure 4. Typical Waveforms in the Stabilizing Amplifier
(Refer to Figure 3)
Model 3103
CIRCUIT DESCRIPTION
DC AMPLIFIER
The DC Amplifier section consists of V101,
a type 12AX7 tube used as a differential amp-
lifier, and V102, a type 6BR8 tube used as a two-
stage regenerative amplifier with cathode follower
output. The input signal (or summing junction
voltage) is applied to Pin 7 of V101. The stabi-
lizing amplifier output as well as the external
balance voltage is applied to the second grid of
this tube. Regeneration in the second stage is
accomplished through the common cathode coup-
ling resistor R122. The neon tubes 1101, 1102,
and 1106 provide a constant voltage drop between
the plate of V102A and the grid of V102B, thus
biasing the cathode follower output stage cor-
rectly to produce a zero volt output in the quie-
scent condition. The use of this low impedance
means of coupling contributes to the high gain
of the stage. The overall amplifier is inherently
very stable. Capacitors C105 and C107 provide
high frequency compensation for improved fre-
quency response.
OVERLOAD CIRCUITRY
In the Model 3103, an a-c output voltage
is obtained from the plate (pin 1) of V103 in the
stabilizing amplifier and is available at the
chassis connector Pin J (or Pin K) for utilization
in an external true-overload circuit. True over-
load exists when the signal at this point exceeds
approximately 20 volts, peak to peak, reflecting
an excessive level of voltage at the summing
junction of the overall amplifier. When this con-
dition occurs, the voltage fires a thyratron in the
external overload indicating circuit. Voltage
overload for the Model 3103 is also indicated
by external circuitry. A neon lamp is placed a-
cross the voltage divider network connected to
the amplifier output. When the output voltage
exceeds approximately +100 volts, the lamp fires.
BALANCE CIRCUITRY
The balance voltage applied to Pin 2 of
V101 is obtained from an external ‘‘zero’’ or
balance potentiometer located on the computer
or amplifier receptacle panel. Voltage is applied
through a network consisting of R106 to R109
and C104, which has an exceedingly large time
constant in order to minimize fluctuations in the
balance voltage source. The balance voltage is
adjusted to produce zero volts at the amplifier
(connected operationally asa high gain ‘‘summer’)
is also zero volts.
Model 3103
The trouble shooting procedure described
below will enable the service man to check the
operation of the amplifier and determine systema-
tically the source of trouble. Power is applied
for all tests. A sensitive oscilloscope and high
impedance millivoltmeter (Kintel Model 202B or
Belleville-Hexem EIR meter, Model 110A) are
required. In making the tests, use the second
amplifier channel on the chassis or one on an-
other chossis known to: perform well, to obtain
normal indications for comparison. As a rule,
component detail numbers given in the text will
refer only to the A amplifier channel. Refer to
the schematic diagram for the equivalent B chan-
nel detail numbers. Always try tube and chopper
replacement before making the other tests pre-
scribed.
Symptoms
A. Nervous Amplifier — output voltage observed
during balance adjustment drifts beyond
specified balance range, possibly by a factor
of 10 or more.
Analysis: Low gain in stabilizing amplifier.
Test: Make gain test as follows: Apply a +]
millivolt signal to the amplifier input termi-
nal (A), using no amplifier feedback resis-
tor. Measure the output voltage at pin 2 of
V101 using a very high impedance (approxi-
mately 100 megohms) voltmeter and allowing
about one minute for the meter to reach
maximum indication. The reading should be
at least 0.5 volts, d.c. Reverse the input
voltage polarity and repeat the measurement.
Correction: Replace V103 or V104, chopper
Y101. Check resistance of R110 to R112
and other components in the stabilizing
amplifier. If gain is normal, replace V101
and check associated components. Replace
C102 or C103.
B. Saturated Amplifier:
Analysis: Usually fault is in high-speed path
or may be combination high-speed and sta-
bilizer section faults.
Test:
(a) Cut out the stabilizer section by short-
ing to ground at the junction between CR101
and CR102. Now try to balance the amplifier.
The adjustment will be extremely sensitive,
but if a zero output can be obtained, the DC
amplifier section is normal. Refer to Symp-
tom A for hints on locating trouble in the
stabilizer section.
Model 3103
SERVICING
(b) If the output is still saturated, check
the DC amplifier section gain with no feed-
back resistor: apply a +1 millivolt signal
to the input (terminal A) and measure the
change in output at pin 1 of VIOI. It should
be at least 40 millivolts. Under normal con-
ditions, the output voltage at terminal H
will change at least 40 volts for a +1 mv
input.
Correction: Replace tube V101 or V102.
Measure their tube pin voltages per Table.
C. Will Not Balance
Analysis: Stabilizing Amplifier Section.
(a) Equal but opposite offset in the two
amplifier channels indicates that one side
of the filament voltage source is grounded.
(b) Unbalanced demodulator section.
(c) Noisy chopper.
(d) Excessive 60 cps pickup caused by
cathode-to-filament leakage.
Correction: Check CR101, CR102 and asso-
ciated components. Replace V101 or chopper
Y101. Clean printed circuit board to remove
dust, etc., between filament and signal
lines.
D, Excessive Hum (60 cps)
Analysis: V101 or V102 leaky. If amplifier
output is saturated at 60 cps, check for
open C104 or R129. See also Symptom C.
E. Oscillation at high frequency (60-80KC)
Analysis: Failure of high-frequency suppres-
sion components. Regeneration components
out of tolerance.
Test: Observe output on oscilloscope.
Correction: Check values of R118 and R122,
Check C105 through C108. Change output
tube V102.
F., Low Frequency Oscillations (approx. 10 cps)
Analysis: Poor power regulation supply
caused by low line voltage. Faulty chopper
Amplifier section. (See Symptom A.)
G. Slow Overload Recovery
Analysis: Second stage in stabilizing ampli-
fier clamping.
Correction: Replace V103. Check R125,CR101,
and CR102,
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PARTS LOCATION
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DONNER SCIENTIFIC COMPANY
A Subsidiary of Systron-Donner Corp.
Concord, California
Supplementary Instruction Manual
For Model 3500 Analog Computer
AUXILIARY PROBLEM BOARD SET
MODEL 3530
Model 3530 Problem Board Set used with Model 3500 Analog Computer
GENERAL DESCRIPTION
The Model 3530 Problem Board Set is an acces-
sory for the Model 3500 portable analog computer
which effectively converts the instrument into two,
independent computers and permits the use of spare
problem boards. It is intended primarily as.an educa-
tional aid, but will greatly enhance the versatility
of the computer in general applications. Each unit
of the problem board set commands five amplifiers
within the Model 3500, three of which may be used
as integrators. On each unit are problem board jacks
corresponding to the terminals on the Model 3500
fixed problem board, three initial condition coeffi-
cient potentiometers, bias voltage terminals, and a
function switch duplicating the Model 3500 function
switch, all of which are utilized in the same manner
as the corresponding controls on the Model 3500 com-
puter. When the cable connectors of the Model 353 )
set are inserted into the corresponding front pane’
receptacles, J407 and J408, of the Model 3500, cll
necessary connections are made from the function
switches and terminals on the units to the amplifiers
in the computer.
Each problem board unit of the set measures
AY, inches high by 8 inches wide by 12 inches long,
and has a 38-inch cable. Shipping weight for the set
of two is 18 pounds.
OPERATION
PRELIMINARY
Place the Model 3500 computer function switch
at ‘‘hold’’ during all operations with the Model 3530.
Remove all patchcords and components from the
Model 3500 fixed problem board and insert the cable
connectors of the Model 3530 units into J407 and
J408 on the Model 3500 front panel. Each unit will
control the following amplifiers in the Model 3500,
as indicated by the problem board legend.
Amplifiers controlled by
Unit connected to
J407 J408 Amplifier Function
Ampl. #1 #4
#2 #5 integrating
or summing
#3 #8
#6 #9 .
#7 #10 summing only
PATCHING OPERATIONS
The patching operations for the Model 3530 are
identical to those explained in Section 4, page 14,
of the Model 3500 instruction manual, with the fol-
lowing single exception. Observe that each ampli-
fier terminal group in the upper row of the Model
3530 problem board panel has three pairs of jumper
terminals indicated thus: )
To utilize the amplifier corresponding to each
set of terminals as an integrator, connect together
the two terminals of each pair as well as the cor-
responding IC terminals adjacent to the like-number-
ed potentiometer. For zero initial conditions, ground
the IC terminal as illustrated on page 15 of the Model
3500 manual.
Each amplifier has four columns of terminals
associated with it. When an amplifier is connected
as an integrator, insert the plug-in input components
between the first and second columns from the left.
To use the same amplifier terminals for summing
operations (that is, when the jumpered terminals
are disconnected), connect a patchcord between the
second and third columns.
The two summing amplifier terminal groups in
the lower row are utilized exactly as explained in
the Model 3500 manual.
The terminals immediately adjacent to the in-
put and output side of the amplifier symbol
on the Model 3530 units parallel the corresponding
terminals on the Model 3500 fixed problem board;
therefore, these terminals on the Model 3500 may
be used to supplement those on the problem board
units when required.
VOLTAGE MEASUREMENTS
All voltage measurements for problems set up
on the Model 3500 problem board units are made
with the meter on the Model 3500. Connect it either
for direct measurements or null operation as des-
cribed in the Model 3500 manual. When a measure-
ment is to be made at the amplifier output terminal,
as for initial condition adjustment, the reading may
be taken at the terminal on the Model 3500 fixed
problem board as well as at the corresponding ter-
minal on the Model 3530 plug-in board. Measure-
ments on the Model 3530 problem board unit may be
facilitated by using the trunk lines to terminals on
the Model 3500 labeled ‘‘1’’ or ‘'2’’. The correspond-
ing trunk-line terminal on each Model 3530 unit is
the sole violet-colored one.
Refer to the Model 3500 instruction manual for
all other operating procedures, including amplifier
balance.
The Model 3530 Problem Board set cannot be
used with the Model 3520 Multiple Control Unit.
MAINTENANCE
The Model 3530 problem board set requires no
adjustment nor routine maintenance. Malfunction
within these units would be confined to defective
switch contacts, potentiometers, and cable connec-
tions. Refer to Dwg. 6282 for circuit connection
information.
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INSTRUCTION MANUAL
MODEL 3732
ELECTRONIC MULTIPLIER
(Quarter Square Type)
Issue No.
Serial No.
July, 1961
SYSTRON €—=3/ > DONNER
CORPORATION
CONCORD, CALIFORNIA
IDENTIFICATION OF AND RESTRICTIONS ON USE AND DISCLOSURE OF PROPRIETARY DATA
The disclosure of this informa
when necessary,
Namen ann Rene ena ..
roprietary rights thereof, but is to be
tion does not constitute
escribed herein must he ohtained in +
used for information Purposes only Permission to reproduce this informa-
arriting fram tha Cywetenne
ee eee
Table of Contents
GENERAL DESCRIPTION .
Function, Different Versions
SPECIFICATIONS .
INSTALLATION
OPERATING PROCEDURES
Gain Adjustment, Terminal Connections
PRINCIPLE OF OPERATION .
MAINTENANCE
List of Illustrations
Model 3732
Title
The Four Basic Versions of the Model 3732 Multiplier .
Terminal Identification on Switch Assembly, Model 3732B.
Terminal Identification on Model 3732A
Signal Connections for Model 3732A
Connections for Multiplication and Division
Connections for Squaring, Square Root, etc. .
Functional Block Diagram of the Model 3732
The Square Curve is Simulated by Straight Lines
Diagram of the Division Circuit . . . .
Schematic Diagram, Dwg. No. 8494 (Model 3732A) .
6701 (Model 3732P) .
Page
10
Page
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9
* Reference
DONNER cc QUARTER- SU "6 Oe : on 9 9732
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Figure 1 — The Four Basic Versions of the Model 3732 Multiplier
1-General Description
1.1 FUNCTION
The 3732 series electronic multipliers offer a
choice of several different packaging versions of
a solid-state quarter-square type multiplier circuit.
Each unit is essentially a dual channel squaring
network which performs the following basic opera-
tions when patched into a computer circuit:
a. Four-quadrant multiplication (single-channel ):
output = -.01XY
b. Two-quadrant division: output = -100X/Y
c. Squaring (two channels): outputs of =~ 01X*
and +.01Y2
d. Square-root (two channel): outputs of +10X?
and -10Y2
e. Fourth power and fourth root
Many variations of these operations are possible
as explained under ‘‘Operating Instructions’’.
The 3732 series normally operates with input
and output voltages of +100 volts full scale, but
for solid-state system applications a +10 volt range
instrument may be ordered. Static accuracy in four
quadrant multiplication is within 500mv (0.25% of
full scale) and within 250mv in the squaring mode.
External operational amplifiers are required with
the quarter-square multiplier. For multiplication,
one amplifier is needed for output scaling and, if
two-polarity input signals are not available, two
input inverting amplifiers are also necessary. Input
and feedback resistors for the associated ampli-
fiers are internally mounted (except in Model 3732A)
and resistance values of the input networks are
matched in pairs to within 0.01% tolerance. The
multiplier normally operates from a +100 to 105-
volt reference supply available in the computer, or
it may be. factory set to operate from another level.
Two screwdriver adjustments are provided for
calibration of the squaring networks. No other ad-
justments are required.
Mode! 3732
1.2 DIFFERENT VERSIONS
Four basic versions of the Model 3732 multi-
plier are illustrated in Figure 1.
MODEL 3732P is packaged as a compact plug-in
unit with operating mode switch which may be
mounted directly on the problem board of a Donner
or other type of analog computer having %4-inch
hole spacing. All interconnections are made to
terminals on top of the case. Case dimensions are
3" x QV" x Q" 3
MODEL 3732R is three-channel (maximum) rack-
mounting panel version. Panel dimensions are 3/2"
x 19". Total depth is 3%" (2%" behind the panel).
MODEL 3732B is the internal switch and com-
ponent assembly of the plug-in multiplier, supplied
without case or signal terminals, for panel mount-
ing in custom systems. The two gain adjustment
controls are supplied unmounted. Dimensions are
2 x 2" x 3" deep.
MODEL 3732A may also be referred to as a dual
squaring network. It is designed as asystem module
and is laid-out on a 3 by 8-inch printed circuit
card which mates with a 15-pin connector. The
operating mode switch and precision resistors for
the external amplifiers are not included, but the
instrument can be connected to perform the same
operations as the other versions.
2-Specifications
Multiplication:
INPUT AND OUTPUT RANGE:
INPUT IMPEDANCE:
ACCURACY:
BANDWIDTH:
PHASE SHIFT:
NOISE LEVEL:
REFERENCE REQUIREMENTS:
SQUARING:
DIVISION:
SQUARE ROOT:
+100 volts (+10 volt version available)
33K ohms minimum
100V range: 500mv (0.25% of full scale)
10V range: 100mv (0.5% of full scale)
With both inputs zero, the output is within 20mv of
zero. Output drift is less than 5mv in an 8 hour
period.
With one input zero andthe other ranging over +100
volts, maximum error in output is within 6Omv.
-3db at 20kes typical
Less than 1° at Ikes.
Will add less than 15mv rms to hum level of ex-
ternal amplifier.
Requires a positive and negative source (with 0.1%
regulation for rated accuracy). Internal adjustment
permits operation from a source between 100 and
105 volts. Current drain is 3ma, maximum. Special
versions operate from as low as + 10V reference.
Static accuracy is within 250mv. Other specifica-
tions as shown for multiplication.
Static accuracy is 0.25% of full scale (500mv)
for X=Y=100 volts. With X=Y, error increases
inversely with magnitude of Y.
At maximum output, performance is identical with
multiplication mode.
3- Installation
3.1 The Mode! 3732P unit is normally mounted
by plugging it into two adjacent unoccupied termi-
nals on the computer problem board. Its two mount-
ing prongs are electrically insulated. They may
be removed by opening the case as described under
‘‘Maintenance’’,
3.2 The Mode! 3732R panel instrument mounts
in a standard 19-inch computer rack.
3.3 The Mode! 3732B switch assembly is mount-
ed to a panel by means of the locknut on the
switch. The two gain potentiometers supplied with
the instrument are furnished with hardware for
panel-mounting. Figure 2 identifies the terminals
on the rear circuit wafer of the assembly to which
the potentiometers and all signal connections are
soldered. Use a low power soldering iron when
y FO ARM ed(-X) @B-
ADuY @ CW @ xX @u(y)
@ CCW @® Be ®@.O1xy
ARM ® GND
x (°® Pu(xy) 5 oY)
ADJ 2 @ CW @.O1Y
® CCW @Y OT
@ xX
Figure 2 — Terminal Identification on
Switch Assembly, Model 3732B
soldering at the printed circuit board terminals. To
enable the Mode! 3732B to be used for all possible
operations, a patch-connection system between the
unit andthe external amplifiers should be employed,
like the terminals on the Model 3732P version.
3.4 The Mode! 3732A plugs into a 15-pin recep-
tacle connector*. Signal and reference voltage
connections tothe receptacle must be made accord-
ing to Figure 3. The Model 3732A may be perma-
nently programmed for a single mode of operation
within a special system; however, a patch-connec-
tion system, as suggested for Model 3732B, will
permit all operations that are possible with the
other versions. The circuitry consists only of that
portion indicated within brackets in Figure 6. The
input and feedback resistors for the external
amplifiers are not included. The use of 1% deposit-
ed-carbon resistors of the values shown in Figure
3 is recommended because of their good temperature
stability. Each pair of resistors should be matched
to the closest possible tolerance. (Donner specifi-
cation is 0.01%). Connections for the basic opera-
tions are shown in Figure 4, By referring to Figure
5B, one can learn how to perform other operations.
Note that jumpers are required between adjacent
input terminals, as indicated in Figure 3, for all
Operations except multiplication and division.
*Methode part No.CD-615S(Donner stock No.J0148) or
Amphenol part No. 143-015(Donner stock No. J0069)
IY GAIN ADJ |
[X GAIN ADu |
B+
GROUND
Be 2
-K(X-Y)
-Ys
-X ~
+Y"}
+X #
Y NETWORK
}x NETWORK
K(X+Y)©. OUT
For omnZtcxAreTrzAvAMHM
Figure 3 — Terminal Identification on Mcdel 3732A (Card Version)
Connect jumpers as indicated except in multiplication and division.
Model 3732
A. CONNECTIONS FOR MULTIPLICATION AND DIVISION
(FOR DIVISION ADD CONNECTIONS SHOWN IN DOTTED LINES}
omit 250K RESISTOR ACROSS AMPLIFIER NO. 3)
mmr rar cnr rrerrenwnrenn =_
14x ;
x 1M -x} X — [k(x+y)® 1
INPUT vy | NET-
(MULT 1M WORK 250K 4
ONLY ual 1 ouTPUT
MULT & DIV)
+X
Y 1M -X Y 2
INPUT -y | NET- -K(X-Y)
(MOCT e WORK 1
4 ory] 1M +Y L
250K
t
!
:
X | NPUT
(D1v ONLY)
+X 250K
| X
1M +Y
x “x ae 1 OUTPUT
| NPUT NORK
-Y
B. CONNECTIONS FOR SQUARING
Y fo
NET - +X
WORK -Y
. iq:
Y 250K
INPUT {> OUTPUT
C. CONNECTIONS FOR SQUARE ROOT
Figure 4 — Signal Connections for Model 3732A
Refer to Figure 5B for polarities of input and output voltages.
4 Model 3732
4-Operating Procedures
NOTE: All operating instructions are given for an
instrument having a range of 100V. For a 10-volt
range instrument, scale all inputs and outputs
accordingly.
4.1 GAIN ADJUSTMENT
Before employing the Model 3732 in a problem
circuit, it is necessary to adjust its accuracy
while operating with the exact bias voltage level
available in your computer. After this initial ad-
justment, subsequent accuracy checks should be
made at weekly intervals or as demanded by the
accuracy requirements of the problem, since the
bias voltage level in the computer may drift. For
optimum accuracy, the gains should be adjusted
in the multiplication mode, if to be used for multi-
plicat