Desk of Ladyada - Stemma Sunday and lots of new designs!
0We churned through a big pile of testers and new designs this week: two IPS TFT displays with EYESPI connectors, the VL53L4CD time-of-flight sensor, the ESP32 QT Py, an OV2640/OV5640 camera breakout, and the ESP32-C3 QT Py. With a lot of our floppy work done and tested for both SAMD51 and RP2040, it's time to move from shugart 34 pin to Apple Disk ][ which uses a different 20 pin interface. The power supply and controlling technique is going to be different for this drive because to save costs they removed and simplified the drive control system.
The Great Search - Positive to negative 12V power inverter for Apple 2 disk drive bias.
https://www.digikey.com/short/5w04zzr2
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!
#deskofladyada #thegreatsearch #adafruit
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