TM 11-6625-596-45
is adjusted to .050 seconds (para 4-6). The simulated
dial pulse output at pin C of 1A3A9P1 is applied to dial
a.
Assembly 1A3A5 provides the following dc
speed assembly 1A3A10 (pin J of 1A3A10P1). Plus 10
voltages.
volts is applied to 1A3A9Q1 and Q2 through pin A of
1A3A9P1.
(1) Plus 24 volts at pin H. of 1A3A5P1.
(2) Plus 10 volts at pin F. of 1A3A5P1.
(3) Plus 100 volts at pin D. of 1A3A5P1.
2-10.
Dial Speed Assembly 1A3A10
b. The 75-volt ac input between pins P and S
of 1A3A5P1 is rectified by 1A3A5, CR1 and CR2 and
Assembly 1A3A10 includes monostable multivibrator
filtered by 1A3A5R1 through R4 and C1 through C4 to
1A3A10Q1 and Q2, which is triggered by pulses from
produce +24 volts at pin H of 1A3A5P1 and +10 volts at
either dial percent break assembly 1A3A9 or the
pin F of 1A3A5P1. Ten-watt zener diode 1A3CR2
telephone dial switch connected to TEL LINE terminals
regulates the +24-volt output, and choke 1A3L1
L1 and L2. When TEST button 1A4S5A is not pressed,
provides additional filtering for the +24 volts applied as
pulses from pin C of 1A3A9P1 are applied through pin J
carbon microphone bias.
of 1A3A10P1, 1A3A10R2, pin L of 1A3A10P1, contacts
7 and 8 of 1A4S5A, pin K of 1A3A10P1, and
c. The 150-volt ac input between pins B and
1A3A10CR1 to the base of 1A3A10Q1 to trigger the
E of 1A3A5P1 is rectified by 1A3A5CR3 and CR4 and
multivibrator. When TEST button 1A4S5A and DIAL
filtered by 1A3A5R5 and C5 to produce +100 volts at pin
SPEED button 1A4S6M are pressed, TEL LINE terminal
D of 1A3A5P1. The +100-volt output at pin D is fused
L2 is connected through contacts 2 and 3 of 1A4S6M,
by 1A3F1.
pin P of 1A3A10P1, pin R of 1A3A9P1, pin R of
1A3A10P1, 1A3A10C2 and R4, pin N of 1A3A10P1,
contacts 9 and 8 of 1A4S5A, and pin K of 1A3A10P1.
2-12.
Negative Power Supply Assembly 1A3A6
When the telephone line switch that is connected to L1
and L2 is operated (the contacts alternately make and
break), the 24 volts connected from pin H of 1A3A5P1,
a.
Assembly 1A3A6 provides the following dc
contacts 10 and 11 of 1A4S6M, pin E of 1A3A9P1,
voltages.
1A3A9R9, pin K of 1A3A9P1 to L1, is alternately applied
to terminal L2 to trigger the multivibrator. The period
(1) Negative 30 volts at pin A of
(time between pulses) of the multivibrator output is
1A3A6P1.
determined by the time constant of 1A3A10C3 and R8.
(2) Negative 12 volts at pins H and C of
The time constant is such that the multivibrator is
1A3A6P1.
triggered on only every other dial pulse. The amplitude
of the output of the multivibrator is controlled by DIAL
b. The 76-volt ac input between pins S and M
SPEED CALIBRATE control 1A4R17. The output of the
of 1A3A6P1 is rectified by 1A3A6CR1 and CR2 and
multivibrator at the variable arm (pin 2) of 1A3R17 is
filtered by 1A3A6Ri through R4, C1 through C5, and
integrated by 1A3A10R13 and C4. When DIAL SPEED
CR3 and CR4 to produce -30 volts at pins A and B of
button 1A4S6M is pressed, the integrated output is
1A3A6P1 and 12 volts at pins H and C. Ten-watt zener
applied through 1A3A10CR2, CR3, and CR4 in series.
diode 1A3CR1, which is connected between pin B of
The pulsating voltage across 1A3A10CR4 is applied
1A3A6P1 and ground, regulates the negative 30-volt
through 1A3A10R15 in series with 1A3A10C5. The dc
output; 100-milliwatt (mw) zener diodes 1A3A6CR3 and
voltage across 1A3A10C5 is applied through 1A10R14,
CR4 regulate the negative 12-volt outputs at pins H and
contacts 9 and 8 of 1A4S6M to meter 1A4M1 to give
C, respectively.
visual indication of the dial speed. Plus 10 volts is
applied to the multivibrator through pin M of 1A3A10P1.
2-11. Positive Power Supply Assembly 1A3A5
2-5
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