Trying to drive a 3V motor with gearbox, using TM4C. Motor specs are given below.

The Motor Specs

First tried with 2N2222A, later plugged motor directly in to LF33ABV voltage regulator. On both setups, motor was quite weak and wasn't moving properly even under small loads. I guess it was because of the 0.5A current limit of the either components.

Then I checked the components at home and found BDX53C power transistor, which can supply up to 8A. After some calculations, here is the setup I'm planning to build. "A" will be connected to one of the TM4C's PWM capable ports.

The circuit

If I don't burn something else then I will later build another setup with 555 timer & potentiometer to replace the launchpad.

Edit: Forgot to mention that, "A" is connected to Port A5 of the TM4C. Both TM4C & battery grounds are connected to each other, although it is not seen on the drawing.


Is it safe to use BDX53C on this setup? If not, can you suggest some components to buy?

  • \$\begingroup\$ What is A connected to? do you have the source for A at the same ground reference as your transistor? How does the return from A get back to the voltage source that supplies A? Were you operating the motor with a load? \$\endgroup\$ – Voltage Spike Feb 5 '16 at 23:50
  • \$\begingroup\$ A is connected to PA5 of TM4C. Sorry I forgat to add: Yes both ground of battery and TM4C will be connected to each other. \$\endgroup\$ – SoajanII Feb 5 '16 at 23:51
  • \$\begingroup\$ The motor should run fine if you connect 3V to it with no load, try a bench top supply to ensure the motor is running correctly. \$\endgroup\$ – Voltage Spike Feb 5 '16 at 23:55

Your transistor has a drop of somewhere between 0.5 and 0.7V, That means you only run the motor with 2.3V which will cut down the delivered power. Consider switching to a relay or mosfet, or get a battery with a higher voltage and use a DC to DC converter.

  • \$\begingroup\$ After checking internet I realized that there are also variable voltage regulators such as LM317 capable of 2-3A. I will get one. Thank you \$\endgroup\$ – SoajanII Feb 6 '16 at 0:18

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