Up Range Detector, Minus Voltage

TM 11-6625-444-14-2

input (U405 pin 6), the high gain output will

5-10. Up Range Detector, Minus Voltage

swing towards the positive supply (+5 V). This

causes a logic "high" to be present at NAND

The reference input (inverting) to U404A pin 1

gate U403D pin 8 and because 4 (figure FO-5)

i s set to produce - 1 9 5 , 0 0 0 counts (approx.

is "high" (Autorange), the output of this gate (pin

-9.75 volts) by adjusting R405. If a voltage >

10) is "low". This turns off the photo-cell U407

-9.75 volts (i.e. -9.80 volts) is applied to the

and causes a logic "high" to be present at U50

non-inverting input (U404A pin 2), the high gain

pin 9; producing a "Down Range command".

( > 10,000) operational amplifier will swing

quickly to the negative supply voltage (-15 V).

This will turn off the photo-cell in U406 and

If the output signal voltage is > -0.6 V (i.e.

cause pin 5 to go high (+5 V). The result is a

-0.7 to -9.75 volts), then the output of U405B

logic "high" at U50 pin 5; producing an "Up

will swing to nearly the minus supply voltage

Range command".

(-15 V) and cause a logic "low" to be at U50 pin

9. This tells the autorange circuits to remain at

the present range.

If the output signal voltage is < -9.75 volts

(i.e. -9.70 volts), then the open collector output

o f U404A goes towards the positive (+5 V)

5-13. Down Range Detector, Plus Voltage

supply, causing the photo-cell in U406 to con-

duct. This results in a logic "low" at pin 5 of

A reference voltage representing + 12,000

U406 and thus; a logic "low" at U50 pin 5. This

counts is applied to the non-inverting input of

causes the autorange circuits to stay (or hold) at

U405A pin 2 and is set to approx. +0.6 volts by

the present range.

adjusting R407. If a voltage < ± 0.6 volts (<

12,000 counts) is applied to the inverting input

(U405A pin 1), the output will swing towards the

5-11. Up Range Detector, Plus Voltage

open collector supply voltage of +5 V. This re-

sults in a "low" from U403D pin 10, turning off

The reference input (non-inverting) to U404B

the U407 photo-cell and causing a logic "high"

pin 6 is set to produce +195,000 counts (approx.

to be present at U50 pin 9. This produces a

+9.75 volts) by adjusting R406. If a voltage >

"Down Range command".

+9.75 volts (i.e. +9.80 volts) is applied to the

inverting input (U404B pin 7), the high gain am-

plifier will swing to approx. the negative supply

If the signal voltage is > +0.6 V (i.e. +0.7 to

voltage (-15 V). This again results in a logic

+9.75 volts), then the output of U405A will swing

"high" at U50 pin 5 producing an "Up Range

to the minus supply voltage (-15 V). This results

command".

in a logic "low" at U50 pin 9 causing the auto-

range circuits to remain at the present range.

If the output signal voltage is c +9.75 volts

(i.e. +9.70 volts), then again a logic "low" will be

5-14. Autorange Logic (A2 Assembly)

presented to U50 pin 5. This causes the auto-

Refer to figures FO-8 & FO-11

range circuits to stay (or hold) at the present

range.

Up Range Command: On any range except

the 1000 V range, a logic "high" is present at

5-12. Down Range Detector, Minus Voltage

U50B pin 6 enabling the NAND gate. When a

"high" (Up Range command) is applied to U50B

A reference voltage representing -12,000

pin 5, a logic "low" is at the output (pin 4). This

counts is applied to the inverting input of U405B

"low" is directed to pin 5 of U51, the BCD

pin 7 and is set to approx. -0.6 volts by adjust-

Up/Down (U/D) Counter, enabling it. The "high"

ing R408. If the voltage is < ± 0.6 volts ( <

(Up Range command) is also steered to U51 pir

12,000 counts) is applied to the non-inverting

10; selecting the up-count mode, see table 5-7

5-8