One day, I just wanted to make a stepper motor rotate. A few TTL chips and a bunch of transistors later, it did.

A few days later, Hack-A-Day published an article about sine-cosine drivers. I had to try it.

What's the shortest path to sine-cosine? A quadrature oscillator made from a high-power dual op-amp. One chip, three resistors and three capacitors. No code, no drivers, no mail-order parts. Best of all, the chip was scavenged from a junked VCR.

I was stunned at how smoothly the motor turned. This project begins...