A window discriminator constructed with transistors and linear and digital integrated circuits is described. The discriminator will separate electrical signals on the basis of amplitude or duration or both and provide a variable output pulse for the desired signal. The useful input range is from 10 mV to 10 V, the time window range from 1 msec to 10 sec and output parameters 0 to ± 10 V, 0.1 to 100 msec. © 1969.