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A small programmable power supply based on the LM2596 module found on Ebay. An ATtiny44A controls the 4 digit LED segment display and features 3 programmable buttons with a rotary encoder with digital potentiometer to adjust the output voltage.

Auto calibration is supported in steps of 0.1-0.2V which means that one click of the rotary encoder equates to 0.1-0.2V change in output voltage (but higher steps occur due to design when you reach 5V and up).

IMG_3232 IMG_3233

PCB Board: 100mm x 50mm
Input voltage: 12-15V
Output voltage: 1.8-12V
Ripple: under 70mVpp (no load), under 160mVpp to 4V (10 Ohms load), under 100mVpp (47 Ohm
load) – not the best but it’s mostly due to the LM2596 module.
Weight: 68 grams


The download file includes:
– Source code and compiled main.hex file
– Parts list and instructions on use (View the PDF)
– PCB Guide
– Schematic
– Pictures of finished product

v1.0 (11 May 2014)
– Initial Release

Example calibration information

Each step of the knob when turned would result in a change shown below.


This kit requires assembly and soldering, you will need your own parts. To reduce shipping costs the kit is sent via the Airmail letter service for $3 and the usual delivery time is 7 – 12 working days (however it sometimes can take 20 working days depending on your location); we ship via Australia Post.
Small Programmable Power Supply PCB board only – $7
This is for the bare PCB itself, no components are included.


Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

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