DIY PSU

[alvieboy]

Hi prasimix, all.

I stumbled across this thread a few days ago, and took the time to read most of it. You guys did an amazing work here! It's a hell of a project, I will certainly refer to your design and discussion in the future.

The reason I found this thread is I am also working on a lab/bench supply of my own, but something not as advanced nor as powerful. The current design features:
- One 5V (fixed) output, with voltage/current measurement and on/off (mosfet)
- One dual output (positive+negative), adjustable from (I hope) +-1.2V to +-14V. Max current 1.5A (it uses a pair of LM317/LM337)
- One main output, from 1.2V to 29V, max 30W, max ~6A.
- Microcontroller programmable, using STM32F103.
- LCD TFT (no touch)
- One rotary to configure
- One on/off switch per output.

The objective of my project is to have a capable bench PSU as cheap as possible, while having some fun in the process.

The main supply (pre-regulator) is a chinese 30W PSU, capable of delivering a 5V rail, a +15V rail and a -15V rail. For the main output a chinese step-down converter (300W) is used, based on XL4016.

Everyting is supposed to fit inside a plastic encosure 200x175x70 which I found online. The front and back panels have been 3D-printed (the prototype ones).

Everything should be configurable using the single rotary present. I am however thinging about adding another one if needed.

The main PCB arrived two weeks ago (was manufactured by JLCPCB, was the cheapest option I found for 2oz copper). I have not yet the full set of components needed, a few are still missing so I have not yet fully assembled the board, but should do it in the next few days I hope, and run some tests.
Attaching the schematics and some photos, including a preliminary design for the LCD output. @prasimix, let me know if you find the 7-segment-like font, I can provide you the fonts I am using.

All of the design (PCB, schematics, 3d-prints, software) are to be provided as open-source. I will also write a blog entry once I have the prototype finished and fully assembled.

Feedback is welcomed

Alvie

[alvieboy]

Forgot to mention two things.

- First the PSU supports CC/CV mode on the main output (I hope, the buck regulator does have two pots for that purpose).

- Estimated BOM is €70. This includes everything but assembly.

Alvie