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UNITED STATES ATOMIC ENERGY COMMISSION
THE TECHNICAL ASSOCIATES SCALER
This document consists of 5 pages.
Dale of Manuscript: May 2, 1944
Date Declassified: March 9, 1947
This document is issued for official use.
Its issuance does not constitute authority
to declassify copies or versions of the
same or similar content and title
and by the same authorss.
Technical Information Division, Oak Ridge Directed Operations
Oak Ridge, Tenr 'ssee
THE TECHNICAL ASSOCIATES SCALE
By Ernest Wakefield
The Technical Associates Scaler with a scale oz 128 is a Columbia-type scaler with a potentiome-
ter in the scaling stage plate circuit. Interstate coupling is the conventional variable air capacitance.
Its method of operation and its circuit diagram, together with its components, are described solely
for informational purposes.
One of these scalers, complete with cables shield, and G-M tube, was ordered for observational
purposes on December 9, 1943 and received March 3. 1944. The scaler is of double cabinet style,
standing almost twice as high as the Offner scaler. Reference to the attached drawing showing
chokes, together with realization of the double height, makes this unit nearly twice as heavy as the
Offner scaler. Mountings of scaler parameters are on small plastic boards, one for each slage. All
the connecting wiring is black in color, is not harness-wired, and is in a black chassis; hence servic-
ing is not easy. A neon lamp is provided for each of the tubes in the seven stages.
Shield, G-M Tube and Recorder
The lead shield, finished in a crackle gray, has quite a professional appearance. The lead is but
1 5/32 inches in thickness, giving a relatively lightweight shield. For comparison purposes, the lead
on a standard Columbia Metallurgical Laboratory shield is 1 1/2 inches, with a brass inner liner of
Mounting of the G-M tube is from two brass rods supporting a Bakelite holder. The tube is of the
Eck and Krebs type, which, unfortunately, was broken in shipment. As the scaler operates on a posi-
tive pulse, the outer electrode is not grounded but brought to the grid of the input tube.
A Cenco impulse-type recorder is furnished. As is known, the external appearance of this is
similar to the Cyclotron Specialties recorder. This Cenco recorder failed the second day of operation.
Due to the relative sizes of C10 and CIl, pushing the reset switch places a negative charge on the
control grid of VI, causing the plate to rise and the neon light to conduct and light. The screen in V2,
connected to the plate of VI, is high in potential, and current flows in this circuit. As a result, the
plate of V2 is at a low potential; hence, all the lower neon-lights are extinguished. A positive pulse
arriving from the G-M tube causes V8 to conduct curr -nt, low ring the potential on the plate, which
places a negative pulse on the suppressor grid of both VI and V2. This momentarily reduces the
current in V2, making the plate more positive. As the screen of VI is connected to this plate, a rise
in the screen potential of VI causes VI to conduct, because the cathode of VI is not as positive as the
cathode of V2, because of the memory condenser. This lowers the plate potential of VI. As the
screen of V2 is connected to the plate of VI, this further cuts off V2, so that the lower neon lamp has
now lighted. VI is now conducting.
The next negative pulse arriving from V6 depresses the suppressor grid potential of both VI and
V2, but succeeds in decreasing the current flow in VI. The plate of this tube becomes more positive,
which transmits tins increase in potential to the screen grid of V2, and memory condenser action
causes V2 to conduct current. The plate of V2 drops in potential, which further cuts off VI and trans-
mits through C2 a nieative pulse, which acts on the next stage as just outlined. Hence, for every two
negative pulse. only one has passed through the stage.
S2 it a selector switch. which permits this scaling circuit to be a scale of 2, 4, 8, 16, 32, 64, and
128. As an example, the second negative pulse arriving at the input to the first stage cuts off VI and
causes V2 to conduct. This action increases the plate potential of VI. This increase in potential,
which with successive pulses give a square wave output from a stage, is carried through switch S2
and sharpened into a pulse by the differentiator circuit C4 and R 13. This differentiated square wave
is applied to the control grid of V3 (a 6917). which acts as a buffer for the multivibrators V4 and V5.
With V5 alternately conducting, a square wave appears at the plate to operate the recorder.
Regulation of the High-Voltage Supply
This circuit is almost identical with the Offner and Higinbolham circuits as described in these
reports. At the risk of recapitulation, the action is as follows: One side of the high-voltage trans-
former is grounded while the other is connected to the plate of a 2K2 half-wave rectifier, the cathode
ol which is connected to the plate of V7 (an 899), which acts as a variable resistance in the circuit.
The cathode of this is the high voltage supply. The control grid of the 809 is in turn controlled by V8
(a 6C6). Suppose the high voltage increases. More current flows through the bleeder resistances,
which causes the grid to rise in potential with respect to the V12 (a VRI05) controlled cathode. This
increases the conduction of V8, lowering the potential of its plate, which in turn lowers the grid of
V7, which effectively increases the resistance in the high-voltage supply. This allows less current
to reach the bleeder resistances, and the control grid of V8 returns to its earlier poential. C12 is
connected between the high-voltage output and the control grid of V8 and minimizes transients and
ripple, similarly to the method just described.
The low-voltage supply is conventional, with perhaps greater attention placed on regulation than
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GEIGER COUNTER, SCALE OF 128 (as furnished by manufacturer), Referring to Figure 1.
Cl 0.1 fi 600 v Paper VI 6SJ7
C2 10-70 guf Air Trimmer V2 6J37
C3 0.1 pf 600 v Paper V3 6SJ7
C4 10-70 ipf Air Trimmer V4 68J7
C5 50 upt Mica V5 6F6
C6 0.05 Iuf 600 v Paper V6 6S37
C7 0.1 pf 600 v Paper V7 809
C8 0.1 if 600 v Paper V8 6C6
C9 2. pf 200 v Paper V9 2x2/879
C10 0.03 if 400 v Paper V10 5Z4
C11 0.005 gf 400 v Paper VII VRI05
C12 l2f 2000 v Oil V12 VR105
C13 1 pif 3030 v Oil V13 VRI05
C14 8 ,f 600 v Oil
C15 8 (if 600 v Oil
C16 8 4f 600 v Oil
C17 8 jp 600 v Oil
TI 6.3 v 2.5 amp 6000 v Insulation
T2 2.5 v 1.75 amp 6000 v Insulation
T3 6.3 v I amp 2000 v Insulation
T4 2000 v 5 ma 6000 v Insulation
T5 Power Transformer Thordarson: T-17R30; 370-0-370 280 ma; 5. v 3 amp ; 6.3 v 7 amp
CHi Filter Choke, Thordarson T67C49 12 henrys 200 ma 80 ohms
CH2 Filter Choke, Thordarson T16C07 32 henrys 85 ma 375 ohms
CH3 Filter Choke, Thordarson TI6C07 32 henrys 85 ma 375 ohms
CH4 Filter Choke, Thordarson T16C07 37 henrys 85 ma 375 ohms
MI 0-1DC Milliammeter
SI SPST Toggle Switch; on front panel, engraved "COUNT" above switch
S2 11-Point Selector Switch Mallory 1315L, on front panel, engraved "SCALE 2, 4, 8, 16, 32,
53 Push Button Switch Mallory 2003 or Utah 666, on front panel, engraved, "RESET"
S4 SPST Toggle Switch, on front panel, engraved "HIGH VOLTAGE" above and "OFF" below
55 SPST Toggle Switch, on front panel, engraved "ON" above and "OF'F" below
CU1 Amphenol 04 Chassis Unit, rebuilt as single contact, using GR Plug, on lead shield
CCI Amphenol 04 Cable Connector, rebuilt as single contact, using GR Jack
CU2 Amphenol 04 Chassis Unit. rebuilt as single contact, using GR Jack, on back panel, en-
graved "COUNTER HV"
CC2 Amphenol 04 Cable Connector, rebuilt as single contact, using GR Plug
CU3 Amphenol 80C1 Chassis Unit, on lead shield
CC3 Amphenol 80FI Cable Connector
CU4 Amphenol 80C Chassis Unit, on back panel, "COUNTER SIGNAL"
CC4 Amphenol 80M Cable Connector
CU5 Amphenol PC2F Chassis Unit, on back panel, engraved "EXTERNAL ON-OFF"
CU6 Amphenol PC3F Chassis Unit, on back panel, engraved "REGISTER"
CU6 Amphenol MC3M Cable Connector used for connecting register
CU6 Amphenol MC2M Cable Connector used for connecting external timer
CU6 CC3 and CC4-require 7030 spring for use with Amphenol 76-22S Coaxial Cable
TJ Banana Jack, on front panel, engraved "1"
.12 Banana Jack, on front panel, engraved "2"
T3 Banana Jack, on front panel, engraved "3"
J4 Banana Jack, on front panel, engraved "4"
L1 Line Switch Indicator Lamp
L2 High-Voltage Indicator Lamp
R1 0.1 megohm IRC Type BT-1/2
R2 800 ohm IRC Type BT-1/2
R3 500 ohm IRC Type BT-1/2
R4 800 ohm IRC Type BT-I /2
R5 I megohm IRC Type BT-1/2
R6 1 megohm IRC Type BT-1/2
R7 0.5 megohm IRC Type BT-1,'2
RB 50,000 ohm IRC Type 3T-1
R9 -50,000 ohm [RC Type BT-I
RIO 25,000 ohm WW Clarostat
R11 50,000 ohm IRC Type BT-1
R12 50,000 ohm IRC Type BT-I
R13 0.5 megohm IRC Type BT-1/2
R14 10,000 ohm IRC Type BT-I
R15 0.1 megohm IRC Type BT-I
R111 1. megohm IRC Type BT-I
R17 0.1 megohm IRC Type BT-l
RIB 0.1 megohm IRC Type BT-1/2
R19 12,000 ohm IRC Type BT-I
R20 25,000 ohm WW Clarostat, on chassis, engraved "REGISTER ADJUST."
R21 50,000 ohm IRC Type BT-1/2
R22 0.1 megohm IRC Type ST-1/2
R23 750 ohm IRC Type BT-1/2
R24 ?5,000 ohm IRC Type BT-1
R25 0.1 megohm IRC Type BT-i
R26 15.000 ohm IRC Type DHA
R27 0.1 megohm IRC Type BT-1/2
R28 0.1 megohm IRC Type BT-1,2
R29 0.5 megohm IRC Type BT-I '2
R30 2. megohm IRC Type ST-I '2 (mounted close to counter tube)
R31 0.5 megohm Potentiometer, on chassis, engraved "INPUT ATTENUATOR";
IRC Type DS 11-133
R32 1,000 ohm WW Clarostat, on chassis, engraved "AMPLIFIER BIAS."
R33 10,000 ohm IRC Type AB
R34 15,000 ohm IRC Type AB
R35 0.25 inegohm IRC Type BT- I
R36 0.1 megohm IRC Type BT-2
R37 1.7 megohm (Bank of three 0.5-meg and one 0.2-meg; all BT 2)
R38 0.2 megohm Potentiometer GR Type 471, on front panel, engraved
"HIGH VOLTAGE CONTROL."
R39 0.1 megohm IRC Type BT-2
R40 2. megohm IRC Type BT-2
R41 10. megohm (Bank of five 2-meg IRC Type BT-2)
R42 1,000 ohm IRC Type BW-1
R43 1,000 ohm IRC Type BW-I
R44 6,000 ohm IRC Type ABA
R45 6,000 ohm IRC Type ABA
UNIVERSITY OF FLORIOA
I I MAlll1111111111
3 1262 08910 9432
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