Dual JK Flip-Flop Stepper Motor Driver

By Christoph Maier

Probably the simplest drive possible is one made with nothing more than 2 flip flops:

Note the LEDs are not needed, they are only there to show the coil signals. Here it is on a breadboard:

And here is one running:

Stepper motor driven by 7476 dual JK flip-flop from Tatzelbrumm on Vimeo.

Now, please note there are many problems with this:

• No way to reverse (it only steps in one direction)
• Very low drive current (only what the 7476 chip can provide)
• Very low drive voltage (chip can't run above 5 volts)
• Very old chip. It is (sadly) hard to find old TTL logic chips these days.^

But the point here isn't to build a great driver, it's to learn how the sequence of signals can be made. These issues can be overcome^ but less expensive drivers are a better choice for actual use. The problem: You never learn how they work!

Also: Digital Logic Tutorial

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