Table of Contents
Advertisement
Circuit 82: Handy diode tester with moving-coil instrument
Setup information
Install the transistor and the two resistors as shown in Fig. 2.82 followed by the three jumper wires. Last
but not least connect the moving-coil instrument. Check the placement on the board again and only then
connect the battery.
Experiment
If everything is wired correctly, you can safely go ahead and test any kind of diode. The measuring current is
so low that the most fragile diodes won't blow. If the test diode is connected in forward-biased, the needle
of the moving-coil instrument shows a clear deflection. If connected the other way round (reverse-biased),
there is no deflection – that would be the result for a good diode. The diode is bad, if in both cases the
result shows a needle deflection on the meter or if in both cases the needle remains at zero.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.82.
Components required:
1 x 2N3904 transistor,
1 x 4.7 kΩ resistor,
1 x 22 kΩ resistor,
1 x moving-coil instrument,
1 x breadboard, 1 x 9V bat-
tery with clip connector
Fig. 2.82: Handy diode tester
with moving-coil instrument
107
Advertisement
Table of Contents
