fan relays?

jhh · Post by **jhh** » Sun Jan 19, 2003 4:38 pm

I've been thinking - a lot of fans will maintain spinning at at 5v but not start at that voltage.

I'm no electronics expert, but maybe you could start up a fan at 12v, and then when it's electrical resistance drops and the current flows more that'd close a relay, switching to 5v or less? It'd be at 12v for maybe a second when the PC is turned on.

Has anyboby tried this? Is there anyone out there who thinks it could be done? I'd be very interested to hear following up this idea since I have a couple of 120mm fans that I usually end up push-starting

jim

powergyoza · Post by **powergyoza** » Sun Jan 19, 2003 6:04 pm

Yes, there are circuit designs that can start a fan at full voltage and then go back down to a reduced voltage. It's not done with a relay but with capacitors.

I've seen it done here, here (scroll down to 2nd step), and here.

Can anyone jump in with a circuit design that can provide a fan with a kickstart? (Marvin? NSY?)

jhh · Post by **jhh** » Mon Jan 20, 2003 5:36 am

interesting, especially the 2nd link (and the safety waring in the first

)