Control Stepper Motor with Sine Waves

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Hello! I’ve read on the forum and around the internet that it is possible to control a stepper motor with two sine waves in quadrature. Sounds like people have been driving turntables this way very smoothly but I have been having a hard time finding concrete info on this technique. I have a small amount of experience in electronics for audio and synths, so to experiment with this I have breadboarded an analogue oscillator that puts out two sine waves 90 degrees out of phase with each other. However, before I just plug this thing into the motor that I have (a stepper motor rated at 3.5V, 1A/phase, 200 steps, bipolar), I just wanted to clarify exactly the kind of signal the motor is expecting so as not to release any magic smoke, and was hoping someone here could help:

  • My motor is rated for 3.5V, so does that mean a 3.5Vpp signal from each sine should do the trick?
  • Currently my sine waves are bipolar. Should I offset them so that they’re each unipolar signals or is the motor expecting positive and negative voltages?

  • If the current draw is 1A/phase, does that mean I have to generate a signal that puts out that much current per cycle?

  • I’ve read that steppers like to be driven at voltages higher than their rating in order to achieve proper torque if I’m understanding correctly. Should I be bumping up my signal to something more than 3.5Vpp? (If we’re dealing with a unipolar signal, I can boost it up to ~14.5V; if bipolar, ~28Vpp.)

    • Thanks for taking the time, much appreciated. Sorry if this isn’t the right forum to be asking these question in!

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    uch a great help for those of us who struggle.Thank you.