wrote in message
...
Not exactly on topic, but close.

I just got a kit from China for the electronics for a 30 volt 3 amp
power supply. The voltage and current are adjustable. I bought it
off AliExpress for $ 3.8x including shipping. No enclosure or
transformer in the kit of parts.

If you look enough you can find a vendor on Ali that has a manual
on line with the schematic. The pcb is 3.25 inch by 3.25 inch.
The vendor I used is

FYD open source hardware

Dan

I already bought all the metered power supplies I can justify in
anticipation of interruptions in trade with China. This output
regulator is the most capable. Before it came out I bought the 50V,
15A model.

https://www.amazon.com/KKmoon-Progra...ding=UTF8&me=&

The unregulated supplies that power them were built around a 24V 250VA
control transformer and a 50A buzz box welder, both with Variacs to
adjust the output. With solar panels connected to the capacitor they
draw AC power only when clouds dim the sun.