Cooling Fan

Hi, i had my cooling fan plugged in the the 2 prongs on the Ramps 1.4 board so it came on when i plugged the printer in, i wanted to have some control over the fan so i hooked it up to D9 and added the buttons to control it on my Pronterface. The problem i'm having is when i run the fan at 50% speed it makes a buzzing noise and is quite annoying however at 100% its fine. Has anyone else experienced this?? The noise doesn't seam to be coming from the fan??

Thanks

Adam

Edited 1 time(s). Last edit at 04/04/2013 03:52PM by adamlister.

put a capacitor between the power cables to the fan

i use a 200uf electrolytic. Works great.

Edited 1 time(s). Last edit at 04/04/2013 04:05PM by lazzymonk.

i'll give that a go, where can i get a couple from? are they 12v??

Cheers

adamlister: fwiw, In general, a capacitor's voltage rating should be chosen above the operating voltage. If you're using a 12V source, use at least a 16V capacitor to avoid damage if and or when the 12V bus gets an unwanted rise due to a motor shutting off/etc. See 'ground bounce' for a hint as to why this happens.