The Great Search: Positive to negative 12V power inverter for Apple 2 disk drive bias #TheGreatSearch @digikey
(Video) The Apple Disk ][ drive is a converted Shugart drive that has three power supplies: 5V, +12V and -12V. The 5V and 12V are for the motor control. Negative 12V is a bit of a pain to generate, but thankfully the -12V seems to only be used for biasing a trim potentiometer. So, we don’t need a lot of current. Still, we do need to generate -12V, let’s take inspiration from the classic MAX232 RS232 driver chip to find a charge pump converter!
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