[ooheadsoo]

Hey guys. I have a fan inside my receiver blowing on the power supply (I think) that is just a bit too loud for my tastes. I was thinking of either buying a more quiet fan or to just put a resistor in series. However, I have no idea what value to use for the resistor. I've tried disconnecting the fan and the amp's autoprotection cuts in once I bump the volume. Any tips are appreciated.

 

[flecom]

i would recommend you make a simple LM317 voltage regulator for it, would work much better than a resistor

 

[ooheadsoo]

Sure that sounds neat, but there's not much room in the case. I suppose it could be done...Any diagrams?

 

[Born2bwire]

Quote:

Originally Posted by ooheadsoo Sure that sounds neat, but there's not much room in the case. I suppose it could be done...Any diagrams?

Well I don't have a diagram but off the top of my head you could probably use a RatShack PC board. Get yourself a molex connector to either mount to the board or split out the wires to hook it up. It should be fairly compact and you could probably come up with a way to mount it to the back of the fan.

 

[strogg]

you shouldn't use a resistor, since fans use more juice than typical resistors. you're better off getting a reostat or a pwm voltage controller. if you have an AC fan, you can just use a light dimmer.

 

[ooheadsoo]

I'm pretty sure it's a dc fan. You guys sure a resistor wouldn't cut it? A resistor - I can handle that. The rest, well, I'm gonna need a bit of info :\

 

[flecom]

look up the datasheet for the LM317, the diagram is in there, trust me its easy as pie, its one TO-220 IC (heatsink it!) two caps and a pot... think there may be a resistor, but either way its dead simple to make a basic LM317 voltage regulator, you can make it from parts @ radioshack even

 

[beamrider]

2 caps, 1 resistor and a pot, or once you find the voltage you want, it's 2 caps and 2 resistors. The entire dealie built can take up less space than the heatsink you'll bolt to the TO-220.

OT: Flecom, mod at the [H]?

 

[flecom]

yep that would be me

 

[beamrider]

Quote:

Originally Posted by flecom yep that would be me

Heh, thought so, but the name looks weird to me when it's not all in caps....

 

[flecom]

this forum apparantly dosent let you have all caps usernames

i registered as FLECOM but it shows up as flecom, meh

 

[guzzler]

You can buy a higher wattage resistor. You'll need to know the current the fan nominally draws, and then your desired voltage drop. Then use

R=V/I where V is the voltage drop, I is the nominal current

Then calculate the power rating:

P=I^2 * R

easy! You can use the LM317 way, but it will use a bit more space.

For PWM, there is a guide over at Bit-Tech using the Micrel MIC502

g

 

[brschmid]

this is funny, i am trying to do the exact same thing now too, only i added the fan myself

Will the LM317 work with an AC fan? 115VAC

edit: damn, nope it wont

 

[PinkFloyd]

This may sound stupid but why not either replace the fan with a quieter fan or take the existing fan to bits and grease the bearings?

There's no point in slowing the rpm of the fan as it's there for a purpose..... to dissipate heat, if it's noisy then address the issue with a new fan / noise dampening.

 

[Daroid]

Why not just use a simple diode ? It will lower the voltage by 1.2V. You can always put more in series and use a rotary switch to switch between them