The Model 5242 is a voltage-controlled power amplifier designed exclusively for Magtrol’s Model HD‑825 Hysteresis Dynamometer. Because of its double braking system, the HD‑825 requires more than 4 amps of power in order to reach full torque. The 5242 (which can provide up to 5 amps of output current) is necessary in order to amplify the power between the DSP7010 Controller (which has a maximum current output of 1 amp) and the HD-825 Dynamometer.