A kindergarten project, I am sure.
How can I simulate an attached 12V fan to the sensor of a PWM fan controller? The simulator should also run on 12V to keep things simple.
I need it for my homelab - a personal collection of old servers and datacenter network switches and routers, mostly for educational purposes. The problem is that equipment like this comes with these small, insanely loud fans. When I replace the fans with larger and quieter ones, the fan controller senses that something is off and I start getting annoying warnings, or temperature sensors stop working, or some of the equipment might refuse to boot.
I have tested attaching a 555 timer to the sense wire of the 4-pin fan connector and running the timer at the highest pulse rate which I was able to detect with a multimeter (and a hairdryer : ) This usually works because when the sensor senses a pulse rate that is higher than what it expects for the PWM signal it sends, it usually doesn't mind. However I want to build something which closely mimics the fan that was previously attached.
I am sure that there are many different options available. The input is a PWM signal and the output is a corresponding timer signal.
The device should be some combination of these:
1. Simple - no complicated programming environment etc.
2. Small - I might have to squeeze these in tight spaces - like inside of packed power supplies
3. Heat tolerant - mounting them might be a problem, they might have to dangle on top of motherboards wrapped in electrical tape
4. Cheap - I would need a lot of these, so the cheaper the better.
Thanks for your advise!