Elenco 23 Range 20k/V VOM in Kit Form - Manual (Page 18)

h
FE
Measurement
Figure 8 shows a simplified diagram of the h
FE
measuring circuit for PNP transistor. Here the range switch is in
the X10 ohms position and the transistor circuit takes the place of the external resistor in the ohms measurement.
The higher the h
FE
of the transistor, the more current flows in the external circuit and the lower the effective
resistance. The meter reads this resistance and the h
FE
of the transistor may be read on the h
FE
scale.
Figure 8
-17-
Battery Test
Figure 9 shows a simplified diagram of the battery measuring circuit. The battery voltage is measured under a
0.25A load.
DC NULL Test
Figure 11 shows a simplified diagram of the DCV (NULL) circuit. The meter is set to 0 on the DCV (NULL) scale.
Positive or negative voltage applied to the terminals causes the meter to swing in either direction.
Buzzer Test
Figure 10 shows a simplified diagram of the audio continuity circuit. When a 20
Ω load or less is place across
the terminals, transistor Q3 conducts and allows Q3 to oscillate.
Figure 9
Figure 10
Figure 11