12v dc fan

[John_P_WI]

Any of you guys had any experience running a 12v dc fan at 9v? I have a design with numerous mosfets and heat may be of concern. I have a 9v dc rail and plan to use a thermister to turn the fan on and off, just wondering if 9v is enough to start and run the fan before I buy one. Thanks.

[UR12]

Any of you guys had any experience running a 12v dc fan at 9v? I have a design with numerous mosfets and heat may be of concern. I have a 9v dc rail and plan to use a thermister to turn the fan on and off, just wondering if 9v is enough to start and run the fan before I buy one. Thanks.

I have run a 12v fan like on a CPU heatsink on one amp I built with VVR. I was just experimenting to see how much air it would move and if it would keep the mosfet cool. I ran the fan off of a rectified heater winding at about 9v DC and it worked just fine. It ran a little slower than normal but I felt that was an added benefit because it was quieter than normel. It did function well as far as cooling the heatsink but it was only on a 50 watt amp. The fan I used was one of the DC brushless designs and I never had any trouble with it turing on. Mine ran all the time so it came on if the amp was on. I am just not all that keen on running fans. I see too many of them get full of dirt and eventually stop working on some of the bigger SS power amps which usually cause a catrostophic failure of the output devices. But having said that, there are fans in almost every PA high power amps on the market.

[John_P_WI]

Thanks Dana. That is exactly what I was looking for, that it would run and would be quiet. This will be for a basement jam amp and I don't want to hear the fan....

Thanks again.

[Firestorm]

Check a computer parts supplier for the best selection. Most have specifications showing bearing type, airflow and noise. Ball bearings are usually better than sleeve bearings. You can find some rated for 50,000 hours. There used to be a nifty one from Thermaltake that came with a thermistor that adjusted speed to temperature, but seems to have gone EOL.

[John_P_WI]

Firestorm Thanks! I'll check into it...

I just dug around in my basement and found a Panasonic 12v fan. I'll take it to work tomorrow and throw it on one of the variable dc supplies. Seems a little power hungry at .2 amps though...

[Phil_S]

I've read in a number of places that suggest running a fan at half voltage to achieve half speed and reduce noise. I can't imagine 9V is going to create any sort of problem and the slower speed may be exactly what you want. I think this needs to be an exhaust fan, not intake.

[John_P_WI]

IF any one is interested here are a few numbers and notes:

Panasonic DC Brushless fan, 80mm, 12v 0.19A ratings.

This thing would start at 5v dc no problem, almost no air flow and no noise.

6vdc, 69.5 ma, gentle (little) air flow and quiet.
9vdc, 103 ma, decent air flow and quiet.
12vdc, 139 ma, strong air flow and noticeable noise.

Yes, looks like I'll run it full time off of the 9vdc rail.

Thanks,

John