"Larry Jaques" wrote in message
...
On Tue, 7 May 2019 07:12:47 -0400, "Jim Wilkins"
wrote:

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.

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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Support the 2nd Amendment

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.