DIY sound synthesizers and me.

+5V eurorack power adapter for 1 euro

Some eurorack modules still use +5 V voltage busboard rail. If your PSU doesn’t supply it, you need to get a 5 V adapter (or get a new PSU). Doepfer “low cost” adapter costs around 15 euro. My alternative is much cheaper – project is very simple and all parts costs about 1 euro (but you scarifice your precious time to build it – f. e.  if you are a NASA pilot, this one can cost you hundreds of dollars 🙂

Adapter uses common 7805 voltage regulator in TO220 and 2 capacitors. In theory it can supply 1,5 A of current, but taking relatively small heatsink into consideration it will be much less. Remember, the 5 V is regulated from 12 V rail, so if you take 100 mA from regulator, that means you got 1,2 W from PSU and wasted 0,7 W for heating your system.

5 V adapter schematics

5 V adapter schematics

Voltage regulator with heat sink are mounted on the copper (TOP) side of the PCB, capacitors and 2×8 power connector on the BOTTOM side. This way you don’t have to etch double-sided PCB, you can also use this design (see attachments under this post) to move to prototype PCB.

Adapter PCB with values (red = TOP = copper side)

Adapter PCB with values (red = TOP = copper side)

The PCB fits into heatsink (V7110 type), so the completed device looks really neat. I used thermally conductive silicone pad under the voltage regulator.

5 V adapter, front view

5 V adapter, front view

5 V adapter, side view

5 V adapter, side view

5 V adapter, front view

5 V adapter, front view

I have tested it, used it, works great, but I must say:

“This is a part of an eurorack power supply. Use this project for your own resposibility”

Jack

 

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