Power Supply Circuit for PMDC Motor Controller-28V-4A

This circuit is the part of a bigger project – 3 Speed PMDC Motor Controller without using a micro-processor.

PMDC means Permanent Magnet DC Motor. PMDC Motors can deliver high starting and acceleration torque and predictable motor speed. It’s compact in size and highly energy efficient. The application ranges from battery powered wheel chair, power tools, conveyors, door controllers, welding & X-Ray equipment, tomography systems, pumping equipments and numerous other applications.

Most of the PMDC Motors are rated at 12V or 24V, and some Motors are rated at 36V DC. The Power supply circuit is an integrated unit to supply 12V-28V (adjustable) for Motor supply, 12V DC for control circuit and +5V DC for Logic Circuits.

electronics15.com_circuit_28V-4A_dc power suplly

 A 30V / 5A transformer delivers 30V AC to a 10A Bridge Rectifier block. The output of the bridge rectifier will be about 34/35V DC and is smoothened by a 3300MFD / 50V electrolytic capacitor to get pure DC Voltage at the Input of the LM1 – 317T Regulator.

LM1 is a TO-225 package variable voltage regulator whose output can be adjusted to get 12V to 28V DC (as may be required) by P1 (5K Trimpot). The output of LM1 passes through a TO-3 Transistor 2N3055 to boost the current to 5Amps. The output is available at the emitter of T1 which is the input of LM2 – LM317T. LM2 is a TO-3 package regulator and supplies 12V DC for the control relay circuit. The output of LM2 is the input of LM-3 which is a  TO-3 Package 7805 regulator. The LM-3 output is +5V DC for the control logic circuit.

Regulator Package details and pin connections are provided in the circuit diagram.

Here is the Bill of materials (BOM) for the above circuit:


The above circuit is designed and tested by Sonu Perito. If this circuit is useful to you, please provide a feedback.

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