hey guys!
im planing on using 2 old amd x2 heatsink+ coolers to cool 2x50W LEDs. the thing is that the cooler is way too loud when powered through 12v, but i noticed that if i wire togheter the tacho and PWM wires (in my case yellow and blue) the cooler slows down just to about the right speed not to be too noisy. my question is: wiring the tacho and PWM togheter, what exatly happens? is it safe to use the fans like this for long period of time? the fan model is Nidec Beta SL 12v dc 0.10A

ps: i found nothing on the webs to answer my question, so here i am

thanks!

 

Hi,

It must be just the right combination where the tach puts out just the right PWM to drive the fan at a slower speed.

A series resistor also does the job, but often has to be a power resistor.

 

The tach is intended to be read by an external device to verify correct fan speed or to alert in the event of a stopped fan really.. Usually a per rev open collector or something like that
The PWM is intended to be powered by an external PWM signal to control the fan speed..

Get a different fan IMO... Or just use 9V or 5V vs 12V... Or provide it a PWM signal to slow its speed..

Are you planning on having "dimming" of this LED fixture?
If so assuming you have a 5V PWM for that you might be able to use it to adjust fan speed based on LED brightness...

 

no dimming, i want to keep it as simple as possible and i cant use anything lower than 12v, the power suply im using has only 12V output. wiring the tacho and pwn seemed the simplest way of slowing it down, but i have no clue if its damaging the fan in any way on the long run.