StepTest 1.

During the Cyclone mechanical build I hate when I have to wind various axes by hand from one end to the other. I was thinking. What if I build a simple circuit for the stepper motors to do this for me. No MCUs, just a stepper driver, a variable oscillator with a speed control potentiometer, a direction control switch, and the necessary power supply.

I wanted to keep it as simple as possible, so I just picked up two schematics from the net as base.
The DRV8825 stepper module minimal config from pololu:

(source: https://a.pololu-files.com/picture/0J4232.1200.png)

And a 50% duty 555 config:

(source: http://www.electronics-tutorials.ws/waveforms/555_oscillator.html)

I used 680nF in the place of the C1 and a 1K resistor in series with a 10K potentiometer in the place of R2. Here are the result.
Slowest:

Fastest:

This allows me to change the frequency between 74 and 704Hz.

In addition to the two circuits above I added a simple 78l05 regulator, so the whole circuit runs from a single 12V supply.

Here is the build on breadboard:

During the test I realized, that the motor is quite noisy. So I think to use the microstepping and in parallel increase the frequency by reducing the value of the C1.
Next: proper build.