Product Description:

The 4212 is a single-axis DC servo amplifier produced by Copley Controls within the DC Servo Amplifiers series. As a current-mode drive, the unit regulates armature current to control torque in brush or brushless DC motors used throughout automated machinery. By processing ±10 or ±20 V command signals from a motion controller, it supplies bidirectional power to actuators that position stages, conveyors, and pick-and-place heads with millisecond response.

The velocity loop is supported by a bandwidth of 3 kHz, allowing the amplifier to track rapid command changes without excessive phase lag. Under steady loading, it delivers a continuous output of 6 A, translating to ±6 A at a ±120 V bus potential. For acceleration or shock loads, the current ceiling rises to 12 A for up to 1 second, and that short-term capability corresponds to ±12 A at the same bus voltage. Pulse-width modulation operates at 25 kHz, keeping ripple below the motor’s mechanical bandwidth and minimizing audible noise. An output resistance of only 0.1 Ω reduces internal voltage drop and heat dissipation, so most of the supply voltage is applied to the motor terminals.

Input power can be drawn from supplies between 22 VDC and 125 VDC, which lets the 4212 serve low-voltage mobile equipment as well as high-energy stationary axes. The current loop remains stable with motor inductances from 200 µH to 40 mH, so both compact ironless motors and large-frame motors can be driven without additional series reactors. Command signals enter through a differential stage that presents 94 kΩ of impedance, reducing the load on upstream digital-to-analog converter cards, and are recognized once they exceed the 2.5 V logic threshold. Protective circuitry triggers a controlled shutdown after overcurrent events. The circuit resets automatically after 200 milliseconds, restoring operation without external intervention.