The circuit was designed without the use of a power supply or a moving coil voltmeter to create a quick battery tester which can test 1.5 V to 15 V battery cells with a two-LED display. BC337 – a ...

Alternatively, you may want to connect its inputs and output in parallel with IC1.C to increase its drive power to the transistor test circuit. IC1.A and IC1.B together with R2, R3 and C1 form an ...