A new pulse amplitude discriminator, especially suitable for counting experiments, has been developed. Ten units were built and tested, and all of the threshold temperature coefficients are in the range −0.03 to +0.12mV per °C. At very high rates the threshold is stable and the output pulse width and the dead time change negligibly. Since the unit incorporates a number of convenient features, including provision for automatic dead‐time correction, it is an extremely versatile instrument.