The presented circuit measures currents and voltages with precision that depends on the tolerance of the resistors used. The instrument is a microammeter and more scales can be added.
This circuit from a Radio Electronics from February 1966 uses an LDR as a sensor. The transistor is a...
The trigger signal for this circuit is an audio tone. Tones up to close to 100 kHz can be used. The...
This transistor tester configuration can be found on this website with many variations. The...