Build your own USB powered Eurorack PSU
For the versatile LEET modular project, I designed a 3HP power supply that converts 5V USB-C to +12V and -12V. It is convenient to use, but not suited for powering a large number of units.
It should be quite straight forward to build it on a stripboard if you don’t have access to a 3D printer.
Specification
- Easy to build – only five components
- No need for a custom PCB
- Small formfactor (3HP)
- Power it from your computer or power bank.
- Suitable for small loads (5-6 LEET modules when powered from USB)
BOM
- USB-C breakout PCB
- CN6009 Step up DC/DC module
- MP1584 Step down DC/DC module
- Small slide switch (~20x6x13 mm)
- 2×5 pin header
- PLA for the 3D printer
Build
Download the 3D models and print them. I used the following parameters:
- PLA material
- 0.4mm nozzle
- Support for the main body
The assembly is quite straight forward, but the limited space makes it a bit challenging. I recommend that you connect everything outside the case, with wires in suitable length and then trim the voltages (+/-12V). When everything works – move it in place and resolder wires when necessary.
Test the unit carefully before you connect it to other modules. It works great for me, but build and use it on your own risk – I do not take any responsibility for damage caused by this project.
Download project files
All files required for this project are available at this GitHub repository:
https://github.com/vonkonow/LEET-Modular/tree/main/power
License
This project is open source under MIT License
(Attribution is optional, but appreciated /Johan von Konow ;)
Hi! I’m quite sure that you shouldn’t vamp 5v from usb-c like this. We should need a little usb-c board to ask a tension and current to the power supply and protect the project.
Please take a look at “SparkFun Power Delivery Board” for reference.
Thanks for the tip!
It depends on how much power you want to source from the USB interface and what is providing the power. By adding two 5k1 resistors between cc and ground on UFP you can get up to 3A, and by digitally negotiating with the host you can raise the voltage to get even more power. But I see no reason to push the step-up more than the default power plus my power bank doesn’t have any intelligence so for me this works as intended. I have even noticed that the built in current limitation works when I reversed an op amp by mistake :)
It would be cool to build a 100W PSU with digital negotiation, but it seems easier and more efficient to use the not so common 5V eurorack power pins instead of going from 5 to 12 and then 12 to 3V3…
Oh ! I’ve forgotten the two 5k1 resistors trick ! 5volts 3amps seem plenty, near to the limits of CN6009 (4amps).
How much power without negotiating or the two resistors ?
5×3 = 15watts… 1 amp is sufficient to be killed, the 100watts limit seem so dangerous now that I think about it (and chines cables…).
How much mA does can it draw? I see most of are 300mA so around 1 big module and two smalls or 5-6 small modules, I own 2 different USB power Wich are very different from another.. yours seem like the GO! From Rakit! It seems to draw a lot more, sorry if I’m not clear… I’m still Newb in this domain.😅
The power out is highly depending on the power in. If you connect it to a computer or a hub, they will probably limit their output to ~1A or less, leading to <=0.4A @12V. If you connect it to a 5V Power supply it should convert up to 4A to 1.6A@12V.
Please note that this is theoretical figures (the heat dissipation is minimal), use the PSU for small loads :)