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Here’s a useful buck-boost DC-DC converter from eBay, this one will do 36v DC at 6A maximum output current. Voltage & current are selected on the push buttons, when the output is enabled either the output voltage or the output current can be displayed in real time.
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Here’s the display PCB, which also has the STM32 microcontroller that does all the magic. There appears to be a serial link on the left side, I’ve not yet managed to get round to hooking it into a serial adaptor to see if there’s anything useful on it.
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The bottom of the board holds the micro & the display multiplexing glue logic.
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Not much on the mainboard apart from the large switching inductors & power devices. There’s also a SMPS PWM controller, probably being controlled from the micro.