Forward/Reverse engine using 2 micro pins - How?

I've been wanting to get into more advance projects after i've down lights, tunes, and other things. So first to mind, knex and motors. have tones of it. The only problem, How can i get a forward/backward on the engine, with just 2 micro pins? This is a normle + - motor.

gmoon9 years ago
Try an h-bridge. Here's a good example. It's minimalist--you'd short the drive current if both inputs are enabled simultaneously. Note that other more robust, non-shorting examples are on that same site...

See the bottom of that page for BEAM type wiring (small sized) of that circuit...

Otherwise, there are lots of h-bridge ICs, for different current requirements. Here's a 1 amp version at sparkfun. Easier than making your own--but I understand why you'd want to build from scratch....
NachoMahma9 years ago
. Use the output to drive a relay that swaps polarity to the motor.
Killa-X (author)  NachoMahma9 years ago
Anyway i can do it with NPN transistors? sence that's the closest thing i have to relays atm
. I dunno. Been too many years since I worked with transistors. Someone who knows should chime in before too long.