L293D Motor Direction Control for Under $2.20

Further to my instructable 12V NE555 PWM Controller for Under $3 I have designed and built a simple and cheap DC Motor Direction Controller that can either be used with the PWM Controller, for speed control or by itself with a 12V power supply.

L293D Motor Direction Control for Under $2.20

I designed this DC Motor Direction Controller so that I could give direction control to DC motors that I am building into mini tools (drill, lathe, table saw, solder smoke extractor, etc.). While, I don’t need direction control for all of the tools that I’m building, it IS necessary for some. Plus, who doesn’t want to spin their DC motor backwards?

The overarching design principles that I’ve used here are:

  1. Works with my NE555 PWM Controller;
  2. Works without my NE555 PWM Controller;
  3. It’s cheap;
  4. It uses minimum parts; and
  5. It works

For the direction controller to work with the NE555 PWM Controller, it will take the PWM modified power from that device and modify the polarity of the signal and push it on to the DC Motor. As I mentioned with the NE555 PWM Controller, I’m only interested in a 12V motor.

To achieve this magic, I’m using an L293D Quadruple Half-H Driver, well … I’m using half of one. If you’re interested, the L293D can manage 36V, however, as discussed in my previous instructable, the NE555 PWM Controller (as designed) will handle 18V max. So there’s your upper limit.

The parts list and costing for this instructable is:

  • 1 x LM7805 Voltage Regulator ($0.40)
  • 2 x 100 nF electrolytic capacitor ($0.06)
  • 2 x 2 pin header ($0.26)
  • 1 x 1k ohm resistor ($0.01)
  • 1 x SPDT slide switch ($0.05)
  • 1 x L293D Quad Half-H Driver ($0.85)
  • 1 x 16 pin DIL ($0.35)
  • 1 x 50 x 33mm PCB ($0.14)

The prices quoted are for parts purchased from eBay that I’ve accumulated over some time. These prices change over time … so caveat emptor, dude.

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