Z-bridge by 74LS139
You can drop all off the transistors and resistors if your motors don’t drain too much current. You only need a 74F139 or 74S139 NOT the LS version. The chip can provide peak currents up to 100mA for a short time (<1 second) and to one output at a time. This is for normal connections. I don’t know how far you can go with this misbehavior. It’s nothing special, but you get the idea how it is done.
Read More Source:
http://library.solarbotics.net/circuits/driver_zoelen.html
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