The model 510A performs Good/Bad test for transistors, FET's, and SCR's. It also identifies NPN or PNP for transistors, N channel or P channel for FET, FET gate lead, all leads of transistors in LO drive, base lead in HI drive, and all leads of SCR. It uses a patented limited energy pulse circuit, which provides highly successful in circuit testing in the presence of low shunt impedance's with complete safety for the device under test. The instrument is designed for a minimum amount of control manipulation, allowing for rapid testing of most devices.