Building a robot

Thread Starter


Joined Sep 1, 2008
Right now, I'm still trying to design a circuit that, with the presence of a signal, the motor will rotate clockwise, and with the absence of that signal, the motor will turn counter clockwise.

I personally don't see any flaws with my design, then again I'm not an engineer or anything remotely close to one

If there anre any flaws, I'd like to know about them. Thanks



Joined Jul 17, 2007
Take a look at Steve Bolt's H-bridge:

While you could use another of the 4 remaining inverters in the 74HC14 to allow control by a single line, I suggest it would be much better to retain independent control over each side of the bridge. If your motor is running full speed in one direction, and you suddenly swap the polarities on it, you'll get very high voltages and currents. It would be much better to hold both inputs to 1 or 0 to brake the motor to a stop before reversing direction.

Bolt's design doesn't have reverse-EMF diodes. That would be a good thing to add. On each side, put a diode between Vcc and the motor, and another from the motor to ground, cathode towards Vcc.
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