The DRV8825 stepper module minimal config from pololu:
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.
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.