This semiconductor tester can be used to test any semiconductor device, from switching diodes to power transistors. Tester is based on a single CMOS IC and a bicolor LED as a visual indication. Gate ICla forms a RC oscillator. Oscillator signal is passed through a buffer and delivered in the form of inverted and non-inverting by the two remaining free gates of IC.
Bicolor LED (red / green) indicates the current sense passing through or from the tester probes tested. Resistor R1 serves current limiter.
Signals from the input and output of IC1c gate are applied to a pair of test probes, a diode test socket and a socket with three terminal transistors. Tested transistor current
the can be adjusted with potentiometer P1. Potentiometer can be calibrated with a known transistor, functionally, to obtain an approximate scale of amplification.
When a semiconductor device is functional, a single LED lights. Color LED indicates when the polarity (PNP / NPN or cathode / anode). When internal component has a break, both LEDs are off. A cage component is easily recognizable by the fact that red and green LEDs light up simultaneously with approximately equal intensities.