30 volt power supply

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
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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.
(Amazon.com product link shortened)
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.
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On Tuesday, May 7, 2019 at 7:12:38 AM UTC-4, Jim Wilkins wrote:

Definitely an order of magnitude more capable, but also an order of magnitude more expensive.
Dan
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On Tue, 7 May 2019 07:12:47 -0400, "Jim Wilkins"

Really cool, Jim. What all does the bluetooth module allow you to do? View only, or control? Have you used the group settings functions to power various goodies? Will yours actually do 750W, and these $1kW?
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The control program can use Bluetooth -or- USB to set the output, or step through a sequence of outputs. However it can't make decisions based on the readings and the designer tells me he doesn't plan to add that capability, so it's not as useful as it could be for automated testing. I'd have to use the interface protocol to write my own program that could detect and respond to limits like the current jump at breakdown or when a battery has reached its charging or discharge voltage limit.
My welder transformer power supply can approach a kilowatt as 30A at 30V but not 20A at 50V, because the transformer's 'constant current' output impedance is around 1 Ohm due to self-inductance, to limit the current when the electrode sticks.
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https://www.aliexpress.com/store/product/4-Bit-0-33V-3A-DC-Voltmeter-Ammeter-Digital-LED-Dual-Display-Amp-Volt-meter-High/2792045_32815000047.html
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