Eurorack USB-C and USB-B Power Supply

This PSU allows to use USB power bank to provide a power source to small Eurorack system. It's great when you're on the go, but can also be used in other scenarios, where you have to use USB power.

While you may find similar looking Eurorack power boards, this one is quite unique on its own.
  • First, for the input source you can pick between USB-B or USB-C connector. USB-B is the simple option, while USB-C comes with an intelligent board, that negotiates the voltage with your USB-C source. As such supports various protocols PD2.0/PD3.0, QC2.0/QC3.0, AFC and can drive up to 5V, 9V, 12V, 15V, 20V (if source supports it). This can be useful for some DC-DC options that can be used with it.
  • Second, there are several choices for DC-DC bricks. The layout allows to install inexpensive 10W DC-DC from Aliexpress, as well as 3W Mean Well and Traco Power high quality converters. The Eurorack ground is also separated from the USB ground, which helps to keep them isolated. You can connect grounds together with a special jumper for that. Also 5V rail is not connected by default, it has a jumper for that too.
  • No ribbon cable extension needed. With 4 Eurorack power sockets onboard, This is enough for small system without needs to use an additional power strip. Just connect your modules directly.

Purchasing options:
  • PCB only: Only PCB board is included, other parts, such as connectors, capacitors, DC-DC, diode and LED are sourced by a buyer.
  • USB-B DIY Kit: Comes with USB-B input socket and other required parts but DC-DC. You need to select DC-DC option separately.
  • USB-C DIY Kit: Comes with USB-C intelligent board and other required parts but DC-DC. You need to select DC-DC option separately.
  • Assembled board: this option is NOT planned at the moment.

DC-DC options:
  • Aliexpress DD1912PA DC-DC converter. Can handle up to 10W, which makes it up to 400mA per rail, however, negative rail sees sagging voltage down to -11V when the load is above 200mA. It's still a good product on moderate loads.
  • Mean Well DCWN03E-12 DC-DC converter. High quality Mean Well part, fully enclosed "brick" can drive up to 3W, which is up to 125mA per rail. If I don't have it in stock, you can get those from Mouser or Digikey
  • new option Traco Power TEM 3-0522N DC-DC 3W converter. Very similar to Mean Well part, but in the industrial package. It only support 5V input source, so, USB-C board should be always set to 5V. If I don't have it in stock, you can get those from Mouser or Digikey

Github file repository:

Assembly instructions:
The board is self explanatory but Github link includes schematics, board layout and photos to help if there are any problems. Here are several notes though:
  • Beginner soldering skills required. There are no high expectations, but being able to read schematics and understand polarity of components are quite important.
  • Populate USB input based on the option selected USB-B or USB-C.
  • Note: It's critically important to set properly jumpers on USB-C module: S1-On, S2-On, S3-Off. This sets the input voltage on intelligent devices to +5V.
  • Important: by default USB input is connected to Eurorack 5V rail. If you don't want this, don't solder Pin 11-12 on all Eurorack headers. Also, careful if you experiment with other DC-DC bricks, or set USB-C module to other than 5V.
  • Important: by default USB ground is not connected to DC-DC Ground. Mean Well DC-DC option provides full ground isolation.
  • If you plan to use 5V Eurorack power rail, then you have to connect both ground together. Otherwise, +5V rail has no ground. It's important either to remove Pin 11-12 on all Eurorack sockets or connect grounds together.
  • Input ground is the upper layer filled zone, while DC-DC output ground is the bottom layer filled zone. To connect them together you can scratch the top silkscreen near central pin of DC-DC connector on the left and solder it to filled area.
  • Follow polarity orientation for LEDs. Square pad on PCB is for the negative pin.
  • Consider proper polarity orientation for capacitors. Inductor L1 has no polarity.
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