a device which lets you see if a given contact (tracing, pin on a chip, etc) is high or low (a digital one or zero) or alternating (between one and zero) -- a very handy tool for determining if some component is alive or dead
(Boolean 0 or 1} of a digital circuit. It is usually powered by the circuit under test (some devices use batteries). It can be used on either TTL (Transistor-Transistor Logic) or CMOS (Complementary Metallic Oxide Semiconductor) integrated circuit devices.