Yaw ILCA Servo Simulator Circuit

55-4920-430-13

(5) When relay K4 is energized, integrator U11 is gated and output modulator U10 is discon-

netted. Relay K4 is energized when the 28 volt vdc hydraulic pressure signal is removed from pin 41 or

when pin 41 is connected to ground at pin 4 by HYD PRESS switch S29. Relay K4 is also energized

when a 28-volt vdc reset signal is present at pin 27. When pin 25 is connected to ground at pin 4, self-

test relay K3 is energized. This connects the self-test input at pins 23 and 24 to the input of the servo

simulator. It also disconnects the AFCS computer servo amplifier output from the input of the servo

simulator U12.

c. Yaw ILCA Servo Simulator Circuit (See fig. 1-6.)

(1) The impedance of the extensible link servo valve is simulated by resistors R73, R74, R75 and

R77 and amplifier U6, with pin 57 of card A1 grounded through 200 ohm resistance. This is the value

of the current sense resistor in the servo amplifier. The gain of amplifier U6 from pin 57 to TP5 is -2

vdc/ma.

(2) The output of amplifier U6 is fed to an integrator, made up of amplifier U5 resistor R76 and

capacitor C10. The integrator simulates the servo valve of the extensible link. Zener diodes VR5 and

VR6 simulate the limits of extensible link travel. The transfer functions of the integrator is -20 vdc/vdc

seconds. Output is limited to -12.5 to +12.5-volt dc by VR5 and VR6. Resistor R80 is selected to es-

tablish the drift of the integrator at zero.

(3) Analog multiplier U4, simulates the extensible link position transducer. The gain of the mul-

tiplier is (X1-X2) (Y1-Y2)

10. When 13 volt ac is applied to pin 1, the voltage at Y1 is fixed at 5-volt

ac by a voltage divider circuit consisting of resistors R85, R86, and R87. Resistors R83 and R84 form a

3:1 voltage divider which fixes the maximum input voltage to the multiplier at about 9 volts dc when

integrator output is maximum. Modulator gain from the integrator output to pin 56 is 0.76 x -0.5

vrms/vdc = 0.38 vrms/vdc. The normal output at pin 56 is 15 vrms/sec-ma. This output is controlled

by the current input at pin 57, which is limited to approximately 4.75-volt rms or 6.7-volt peak. Resistor

R86 is selected to control the gain of the modulator. Resistor R89 is selected to establish the dc offset of

U4 at zero.

(4) With a positive input at pin 57, one yaw feedback output at pin 56 is 180 out-of-phase with

the input voltage at pin 1. The other roll feedback signal at the output of U1 pin 28 is -0.5-volt out-of-

phase in relation to output at pin 56. Load isolation resistors R90 and R101 fix the output impedance

of pins 28 and 56 to about 56 ohms.

NOTE

The output of U2 at pin 44, and of U3 at pin 43 are not used.

(5) When relay K6 is energized, integrator U5 is gated and output modulator U4 is disconnected.

Relay K6 is energized when the 28 volt dc hydraulic pressure signal is removed from pin 42, or when

pin 42 is connected to ground at pin 4 by HYD PRESS switch S29. Relay K6 is also energized when 28

vdc reset signal is present at pin 53. When pin 55 is connected to ground pin 4, self-test relay K5 is

energized, which connects the self test input at pins 58 and 29 to the input of the servo simulator, and

disconnects the AFCS computer servo amplifier output from the input of servo simulator U6.

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