Arduino powered power supply, part 1 : Core

I like to build things cheap.
What i was missing was a "bench" power supply with current limiting.
The idea is that you don't fry stuff when there is a short circuit somewhere (to be more accurate, you are less likely to fry stuff).
Also what i wanted is to have a large range of output voltage, from ~ 1 v to ~ 25 volt.

The end result was the following couple :
* Main to 12v  / 6A cheap PSU (you can find them easily on banggood)
* Boost/buck converter : Search for "automatic lift pressure " on ebay. It must have 3 pots  : CC/CV/Minimal input voltage


There is a very nice reverse enginnering job for these boards available here :
beyondlogic reverse engineering


The first step is to remove the pots, i'd suggest using hot air gun if you can, to do a clean job. Just cutting them and removing the solder will do too.


I dont need the "low input voltage", so i soldered a ~ 36 k resistor instead of the pot (the one closest to input). You can use a wide range of value as long as the divider is above 2.5 v.

The max current pot is easy to modify :

Put a 100k precision multiturn pot and a  1M resistor (it is inside the thermal yellow shrink tube bellow)

That gives a minimum current of about 100 mA, and max ~ 4A  which is inline with the PSU itself

And it is accurate.

The voltage regulation is trickier. It forms a voltage divider with a CMS on the board, not that easy to change.
So i ended up with a cheap trick, a 500k cheap pot in serie with a 100k precision multiturn pot (same as for current)





Added a couple of 0.5 A fuses on the main and the core part is ready to go.
Now let's  add an Arduino.