The Ludlum Model 500-2 Pulse Generator (Pulser) provides the functions necessary for use in calibrating Ludlum instruments, as well as many other scaler/ratemeter instruments. The adjustable output pulse rate is displayed on a three-digit LED readout. Potentiometers (both coarse and fine controls) and a multiplier switch provide rates from 10 to 9.9 x 106 counts per minute (cpm). Pulse amplitude is controlled by a multiplier switch and a LO/HI potentiometer, while pulse polarity is chosen by a selector switch. Amplitude may be varied between 0 and a negative or positive 5 volts; displayed on a four-digit LED readout. The high voltage of the instrument under test is displayed on a four-digit LED readout.