The Dytran model 4119B power unit/amplifier contains a triple–voltage DC power supply (+15V,–15V & +20 DC), a constant current source and a standardization amplifier with low pass filter. The constant current diode, operating from +20 VDC, supplies power to operate the IC amplifier in the 3120B. A 10 uF capacitor couples the accelerometer signal to the input of a two–stage amplifier.

The first stage is a precision attenuator, which sets the system sensitivity to precisely 10.00 mV/g. The second stage corrects the frequency response of the system to provide flat response over the entire frequency range. Model 3120B, when supplied with constant current, self–biases at approx. +10 Volts DC. This voltage appears at the "sensor" jack of the 4119B and is displayed on the front–panel mounted voltmeter as well. This meter serves as a handy trouble–shooting tool when searching for possible system problems such as open or shorted cables.

The model 4119B is supplied as part of the model 3120BK back–to–back accelerometer calibration system.