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Any idea where I can find a 50 ohm potentiometer?


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#1 of 11 OFFLINE   John Pine

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Posted October 15 2003 - 10:47 PM

I checked at Parts Express and a few other on-line suppliers. Any suggestions?
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#2 of 11 OFFLINE   Mark Schermerhorn

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Posted October 16 2003 - 02:55 AM

digikey.com should have them. I'd be suprised if they didn't.

#3 of 11 OFFLINE   John Pine

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Posted October 16 2003 - 04:54 AM

Mark thanks for the link! I'm checking it out now. The site is a little hard to navigate for a layman.
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#4 of 11 OFFLINE   Greg_L_C

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Posted October 16 2003 - 01:36 PM

They Sell POTs at Radio Shack. Just curios, what are you doing?

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#5 of 11 OFFLINE   John Pine

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Posted October 16 2003 - 01:45 PM

Greg: Not a 50 ohm pot. I've built a custom enclosure for my audio equipment and I'm using (2) parallel wired 92mm computer case(2.1W/0.39amps @)fans mounted at the top to vent it. They are powered by an old Rat Shack 12V DC 1amp 25watt power supply. I've plugged the p/s into the "Switched" AC output on my HK525. I need the pot to adjust the fans. I've been told that a pot higher the 50 ohms will have to much resistance. I gotta go to bed, I'm outta' here!
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#6 of 11 OFFLINE   Greg_L_C

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Posted October 16 2003 - 02:11 PM

John,
I've seen several PC cooling parts suppliers selling rheostat fan controls that would work for your application.

Greg

#7 of 11 OFFLINE   John Pine

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Posted October 16 2003 - 10:36 PM

Good idea Greg, I'll check out that angle.
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#8 of 11 OFFLINE   Tim Kilbride

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Posted October 16 2003 - 10:59 PM

Here you go John...

One of many 50ohm trimmer pots @ Mouser.com

#9 of 11 OFFLINE   John Pine

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Posted October 17 2003 - 03:53 AM

Thanks Tim!
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#10 of 11 OFFLINE   John Miles

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Posted October 17 2003 - 04:57 AM

Um, if you try to control 800 mA (or even 1/10 that much) worth of DC fans with a trimmer potentiometer, hilarity (and smoke) will ensue.

#11 of 11 OFFLINE   Kevin P

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Posted October 17 2003 - 05:46 AM

John's right. You'll need a potentiometer/rheostat with a minimum 25 watt rating to control those fans, or else you'll smoke the pot (ok, that didn't come out right!) Posted Image . Or use an adjustable voltage regulator circuit instead of just a pot. Or get one of those universal AC adapters with the voltage switch (usually 3, 4.5, 6, 7.5, 9 volts). With that you can set the voltage to whatever drives the fans at the speed you want.