This high impedance step suggested by an English publication can operate up to 1 MHz with 1 V rms output. Input impedance is 1 M ohm.
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
This power supply is not protected from shorts in the output. Output voltage is given by the...
Any power MOSFET that supports the current of the controlled stepper motor can be used on this...