The HP 546A Logic Pulser is a hand-held logic node stimulator used for injecting controlled pulses into digital logic circuits. The electronics are housed in a hand-held Probe Automatic pulse control is provided for TTL, DTL, RTL, HTL, MOS, and CMOS logic. Pulse amplitude depends on the logic supply voltage (3-18V) which is also the supply voltage for the Logic Pulser. Pulse current and pulse width depends on the load being pulsed. The frequency and number of pulses generated by the pulser is controlled by operation of a push-slide switch on the pulser Probe A flashing LED indicator located in the tip indicates the output mode.