AC fan speed

SGSeeker · 30th March 2005, 12:49 AM

The fan I've been using cools the projector extremely well, so much that the air coming about is barely warm...it makes a ton of noise though. Anyone know which resistors (and how many) I should use to get the fan down to say half and 3/4 speed (with a switch to select). Google isn't helping much

standard 120mm 115v 20w fan. No idea how much voltage it takes to start

SGSeeker · 30th March 2005, 01:17 AM

wait...you can't do that with AC, can you...

SGSeeker · 30th March 2005, 02:58 AM

Okay, how about this. How would I go about having a power switch for the projector...away from the projector. I don't want to send 115v down the line to the switch and back so I'm looking for other choices. I'm trying to centralize the power controls for everything in the room without having unfiltered power running everywhere. I'm guessing my best bet would be just to use like a pc cable and plug one end into the projector and the other into the control box (with power switches for other devices also installed).

Is there some way I can use a relay that sends a tiny amount of power down the line to activate the projector?

Stocker · 30th March 2005, 03:52 AM

It would be

Much

easier to get a similarly sized DC fan and regulate the speed with the voltage. I suppose you could also get lower-powered AC fans and experiment. Try a muffler or baffle setup to kill some of the noise if you want.

SGSeeker · 30th March 2005, 05:40 AM

Only thing I don't like about that is that its one additional wire going to the projector (I'd just use a 7 or 12v wall adapter)

Stocker · 30th March 2005, 06:17 AM

I am ignorant about DIY projector stuff... doesn't your LCD need a power lead?

DC power?

SGSeeker · 30th March 2005, 07:15 AM

power adapter provides just enough for the lcd

anyways, I'll just get a quieter fan or go with a DC later. Now I just want to turn the thing on from a different location and get more from the bulb...3/4 of the light is lost, if not more. We still need to find the right reflector for these things

Dazzzla · 30th March 2005, 09:53 AM

Buy a capacitor fan speed controller.
DJ

wylie-c · 30th March 2005, 04:40 PM

Since it only uses 20w, couldn't you just use a dimmer switch for a light to adjust the speed ?

Luca Brazzi · 30th March 2005, 05:14 PM

You should be able to use a light dimmer, but you might end up with a buzzing sound from the Fan... AC dimmers work by chopping up the AC and reducing the duty cycle of the sine wave. This works good on incandecent lights but with highly inductive loads (fans) it can cause them to buzz.

30th March 2005, 12:49 AM	#1
SGSeeker diyAudio Member Join Date: Feb 2004 Location: WA	AC fan speed The fan I've been using cools the projector extremely well, so much that the air coming about is barely warm...it makes a ton of noise though. Anyone know which resistors (and how many) I should use to get the fan down to say half and 3/4 speed (with a switch to select). Google isn't helping much standard 120mm 115v 20w fan. No idea how much voltage it takes to start

30th March 2005, 03:52 AM	#4
Stocker diyAudio Member Join Date: Dec 2003 Location: Austin	It would be Much easier to get a similarly sized DC fan and regulate the speed with the voltage. I suppose you could also get lower-powered AC fans and experiment. Try a muffler or baffle setup to kill some of the noise if you want. __________________ Jesus loves you.

30th March 2005, 06:17 AM	#6
Stocker diyAudio Member Join Date: Dec 2003 Location: Austin	I am ignorant about DIY projector stuff... doesn't your LCD need a power lead? DC power? __________________ Jesus loves you.

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30th March 2005, 01:17 AM	#2
SGSeeker diyAudio Member Join Date: Feb 2004 Location: WA	wait...you can't do that with AC, can you...

30th March 2005, 02:58 AM	#3
SGSeeker diyAudio Member Join Date: Feb 2004 Location: WA	Okay, how about this. How would I go about having a power switch for the projector...away from the projector. I don't want to send 115v down the line to the switch and back so I'm looking for other choices. I'm trying to centralize the power controls for everything in the room without having unfiltered power running everywhere. I'm guessing my best bet would be just to use like a pc cable and plug one end into the projector and the other into the control box (with power switches for other devices also installed). Is there some way I can use a relay that sends a tiny amount of power down the line to activate the projector?

30th March 2005, 05:40 AM	#5
SGSeeker diyAudio Member Join Date: Feb 2004 Location: WA	Only thing I don't like about that is that its one additional wire going to the projector (I'd just use a 7 or 12v wall adapter)

30th March 2005, 07:15 AM	#7
SGSeeker diyAudio Member Join Date: Feb 2004 Location: WA	power adapter provides just enough for the lcd anyways, I'll just get a quieter fan or go with a DC later. Now I just want to turn the thing on from a different location and get more from the bulb...3/4 of the light is lost, if not more. We still need to find the right reflector for these things

30th March 2005, 09:53 AM	#8
Dazzzla diyAudio Member Join Date: Mar 2004 Location: Australia	Buy a capacitor fan speed controller. DJ

30th March 2005, 04:40 PM	#9
wylie-c diyAudio Member Join Date: Apr 2004 Location: Canada	Since it only uses 20w, couldn't you just use a dimmer switch for a light to adjust the speed ?

30th March 2005, 05:14 PM	#10
Luca Brazzi diyAudio Member Join Date: Dec 2002 Location: VA	You should be able to use a light dimmer, but you might end up with a buzzing sound from the Fan... AC dimmers work by chopping up the AC and reducing the duty cycle of the sine wave. This works good on incandecent lights but with highly inductive loads (fans) it can cause them to buzz.

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