Its recommended to use a IGBT (WG30NC60) transistor.
If you want more power, connect more resistors in parallel.
Source resistance = 1k
Gate resistance = 10k = potentiometer.
The output is gotten from the Drain.
A normal diode of above the 60V.
Don't forget to use a heat sink for the transistor(s)
By adjusting the the middle pin of the potentiometer, you can select your required voltages ranging from 30V to nearly 60V.
There's a voltmeter across the output(drain) to measured the the voltage.
Cheap, Highly efficient and reliable.
