Project information

Title : LED fan switch controller circuits

Date : 14/04/2025

Description : I build a circuit to repair a damaged PC case fan LED lighting system

Problem : The computers case fans which have an LED lighting chain were accidentally shorted and not lighting up properly.

Overview

Unfortunately this project doesn't have much documentation as it was started before I started documenting my projects.

I was originally trying to incorporate an LED CPU cooler fan into the system so that all the fans would turn on and off together, whilst building the original circuit I also damaged the controller which is inbuilt into the first fan in the chain of fans - The first fan is the controller.

Due to the fact I couldn't open the fan I had to treat the item like a black box and attempt to increase the voltage properly, I only did this because I tested the current draw for the control circuit and found that it was a voltage control line and wasn't drawing any or much current, otherwise I would not have taken this approach.

I ended up creating a circuit that could turn all fans on and off simultaneously and also fixing the voltage control line.

I actually had two projects that were similar and my notes are kind of blurred together, in one of the projects I used a two pole relay and created a switch that upon itself but which could only be used if the resistor and capacitor circuit/s gave off a small pulse. In this second project if the pulse was too long the switch would be caught in an endless loop and generate a tonal sound.

The second project was extremely satisfying, timing the pulse correctly by using an oscilloscope and watching it work entirely as intended.

I wish I had more images and videos beyond my project-book notes as these projects were very involved and were fun to do.