Use two buttons on the left top to control power in range of 0 to 7. Left is +, right is -. Display shows the power level.
70mOhm resistor simulates the pot.
Zero voltage switching topology with single power transistor.
Power control is not linear, approximatelly:
1 - 150W
2 - 300W
3 - 500W
4 - 900W
5 - 1100W
6 - 1500W
7 - 2000W
Counter on the right is used as a pulse width modulator, SR flip-flop detects low voltage to switch on transistor
