Eurorack Breadboard Power

Last Update: 3/30/2022

The Eurorack Breadboard Power module attached to a breadboard

Recently I've been prototyping some circuits for my modular synth. Pictured bellow is the old gizmo I used to connect my eurorack power supply to my breadboard. However, after stumbling upon Look Mum No Computer's (LMNC) 5010 Breadboard Helper Bundle Pack This old thing simply would not do.

The old gizmo I used to power my breadboard projects

I love that it plugs directly into the power rails of the breadboard without any need for jumper wires and the added capacitors to filter noise are a nice, easy to add touch. Most of all though the LEDs are a small stroke of genius. I cant tell you how many times I've put together a circuit, plugged it into my power supply and spent 10 minutes trying to figure out why its not working only to find that the supply wasn't plugged into the wall. Never Again.

I could have just bought one but just thinking about waiting for international shipping drives me crazy. I do enough of that waiting for parts from China. besides if you mess around with DIY modular a bit you likely already have the components to throw one of these together.

I will say if LMNC started selling a PCB only version of this I would probably buy it because the distance between the power rails on a breadboard seems to be a little off from the 0.1 inch hole spacing of typical perfboard.


the circuit schematic for the  Eurorack Breadboard Power module

Open as a pdf: schematic.pdf

Bill Of Materials

Part Quantity Description
Perf Board 1 Mine is 30mm x 70mm it needs to be long enough to reach both power rails and wide enough for your components
Power Connector 1 I used 16 pin 10 pin works too
Capacitor 2 I used 22μF
LED 2 Mine are purple but use whatever you like
Resistor 2 I used 1.8kΩ
Male Headers Pins 4-16 I used 4 pins for each power rail you could just use one pin
Wire - For connecting components

The capacitors are optional and help to filter noise. This will com in handy if your working with oscillators or microcomputers. However, they are totally optional given that this is just for prototyping unless you plan on recording using a circuit on you breadboard. A value any where from 10μF to 100μF should work just fine. The LEDs can also be omitted along with the resistors (your LEDs won't thank you for omiting the resistors alone). I used 1.8kΩ resistors but anything more than 1kΩ should do (within reason don't expect a very bright LED if you use a 1MΩ resistor).

If you want to do math like some kind of nerd here is how you can find the current created by the current limiting resistor.

In the follow ing equation:

  • Vcc = 12V from the power supply.
  • VLED = 1.7V a Typical Voltage drop for an LED (The manufacturer should specify).
  • R = 1kΩ or 1000Ω The value of the current limiting resistor.

The Eurorack Breadboard Power module connected to a volt meter showing 23.8 volts

Most 5mm LEDs are rated for about 12mA to 20mA of current (the manufacturer should specify this as well). Choose a resistor value that gives you a current a bit under the LED's rating and you'll be good to go.

Well there you have it. Go build something cool.