Table 5-10. Lamp Intensity Regulator Circuits

TM 11-5865-215-13

Table 5-10.

Lamp Intensity Regulator Circuits

Chassis-

mounted

Regulator

Voltage

Regulator

series

circuit

Control

comparator

driver

regulator

Keyboard

Front panel LAMP

A7U3

A7Q5

(display)

INTENSITY potentio-

lamp

ometer and instru-

ment panel inten-

sity control

Instrument panel

Front panel

A7U2

A7Q2

intensity control

lamp intensity

the conduction of regulator driver A7Q5 and series regulator 02. As

result, more of the +5 V source is applied to the keyboard lamps (in-

creasing the intensity of those lamps).

Rotating the front panel LAMP INTENSITY control knob {potentiometer

R4) counterclockwise (away from ground) provides a more positive input

to voltage comparator U3. This also increases the output voltage of

this regulator, further increasing the keyboard (display) lamp inten-

sity.

A more positive instrument panel intensity control input dims both

the panel and keyboard lamp intensity. A less positive front panel

LAMP INTENSITY control input further reduces the keyboard lamp inten-

sity.

(3) Microprocessor power-on reset. The microprocessor is reset

when power is applied. This is accomplished by power-up sensing com-

ponents R23 and C13, and U4 on CCA Al.

When power is applied to the receiver control, sensing components

R23 and C13 provide a positive edge signal which triggers U4. The

resulting output drives the microprocessor to program memory address 0.

(4) Intercom audio output level control. The df and intercept

receiver audio, (AUDIO B and A), which iS amplified by the circuits of

adc and audio CCA A3, is applied to the 6-channel platform intercom-

munication system via level potentiometers R1 thru R6 and output trans-

formers T1 thru T6 on CCA A7.

Decoder U7 on CCA A7 (see figure 5-15)

(5) Control decodinq.

responds to the microprocessor OC0 thru OC3 control outputs by pro-

viding two functions:

5-38