In the routine testing of electronic equipment, particularly in a nuclear physics laboratory, there is frequently a requirement for a simple, lightweight pulse generator. The instrument described is built to fill such a role. It provides rectangular pulses of duration 1, 10, and 100 microseconds (or other chosen values) of amplitude smoothly variable from 0 to 75 volts. Either positive or negative pulses are available from low impedance sources, and an internal repetition rate, covering the range 1 to 10,000 cycles per second, is included. In addition, the circuit may be driven from an external signal generator, or a source of random pulses, where this is desired. The instrument has proved of utility in circuit research when used as a source of pulses in conjunction with a synchroscope.