June 22, 2026
USB-C from a bench supply
An update on a small adapter I developed for fast USB device tests from a bench supply.
I developed this small adapter to make quick USB device tests easier on the bench. It takes a standard lab supply with 4 mm banana outputs and turns it into a simple USB-C 5 V source.
The design is intentionally simple. It is a passive module with a USB-C receptacle, direct banana plug input, and the usual configuration resistors on CC1 and CC2 so connected devices can identify it as a source. D+ and D- are tied through a 300 ohm resistor for legacy charging detection.
Bill of materials
| MPN | Manufacturer | Quantity |
|---|---|---|
| TYPE-C-31-D-06 | Korean Hroparts Elec | 1 |
| R 1206 51k | UNI-ROYAL | 2 |
| R 1206 300R | UNI-ROYAL | 1 |
| Uninsulated Banana Plug 4mm - M4 connector | - | 2 |
There is no Power Delivery negotiation here, and no controller doing anything clever. It is meant for steady 5 V use when testing small USB-powered loads, development boards, fans, LEDs, and other DIY electronics.
3D render
Three.js preview of the current PSU USB-C adapter prototype.
Model file: psu-usb-c-DdJ47-WR.glb
The design has proven to be simple and useful - capable for supplying up to 1.5A of current to the connected devices at 5V