Chapter 5. CIRCUIT FUNCTIONING

TM 11-6625-539-14-3

CHAPTER 5

CIRCUIT FUNCTIONING

5-1. Introduction

Circuits for Test Set, Transistor TS-1836C/U

can be divided into four functional loops: multi-

vibrator, current limiting, audio amplifier, and

switching. The multivibrator stage produces an

amplified square wave signal that is applied to the

switching circuits through coupling transformer

T1. The current limiting network is provided for

the protection of the semiconductor under test and

to limit the current to the transistor when resist-

ance tests are conducted. The audio amplifier is

used in conjunction with the F. E. T. test to pro-

vide a parallel source to operate the meter. The

switching circuit incorporates a 12-position, 9-

wafer function and a 3-position, 12-pole, 3-wafer

type polarity (FWD PNP/OFF/REV NPN)

switch.

Figure 5-1. Battery check, simplified schematic diagram.

5-2. Battery Check

5-3. Beta and Diode In-Circuit Checks

A simplified- schematic diagram of the circuit

a. A simplified schematic diagram of the cir-

used to check the batteries in the test set is shown

in figure 5-1. With the function switch at BAT,

cuit used to calibrate for beta is shown in figure

5-2. Figure 5-2 illustrates a PNP-type transistor;

+9 volts is fed through series resistor R32 and

however, the same principle applies for NON

meter Ml. The resistance of R32 limits the de-

and four-element devices (tetrodes) when the

flection of meter Ml to the BAT position on the

fourth lead is left open-circuited.

scale.

Figure 5-2. Beta and diode check, simplified schematic diagram.