Variable fan speed circuit |
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MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
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Posted: 14 July 2017 at 9:43am |
Anyone have some schematic for a simple variable fan control that can be fitted to amplifier that does not have any fan cooling?
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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APW
Young Croc Joined: 13 November 2012 Location: Kent, UK Status: Offline Points: 1173 |
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I
have something from a piece of equipment I designed about 10 years ago... It
uses a L200 voltage regulator and a 1K@25C ntc thermistor. I seem to remember
the maximum input voltage being 28Vdc and the fan voltage is 24V.
Here is the schematic if its any good. The circuit was designed for a specific industrial application so probably not optimised for your application, the incoming supply was rectified but not smoothed hence C4 being largish, if your supply is smoothed you could probably do away with C4 and make C1 much smaller (10s of uF), R3 & C5 acts as a soft start and R2 sets the current limit.
R9 and D1 are just for a visual indication of the equipment’s Temperature and can be removed. Edited by APW - 14 July 2017 at 4:46pm |
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ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
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Might be worth checking out the one on the Crest CA series schematics.
Depends what kind of temperature sensor you want to use, thermistor vs pre-linearised sensor IC. Slow PWM (tens of Hz) works quite well for brushless motor control.
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kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
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you could do what HH did and use a Papst variable speed fan. Comes with the correct thermistor n everything
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Kevin
North Staffordshire |
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sajti
Registered User Joined: 03 December 2015 Location: Hungary Status: Offline Points: 23 |
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Bulletproof version, based on Crest PROX200 fan driver.
V2 is LM35 thermal sensor. LT1086 can be LM317. Sajti |
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Greg32
Registered User Joined: 14 December 2004 Location: Australia Status: Offline Points: 116 |
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I have used this one successfully on two different amplifiers. the 12v fan will start as the temperature of the heatsink rises until full speed at your predetermined temperature. Greg
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service dept Steve
Old Croc Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2034 |
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I'm wondering if this is the level of "simple" that was asked for, maybe a bi-metalic switch bypassed by a suitable sized resistor (for a low voltage dc fan) or a capacitor (for higher voltage ac) would provide a usable two speed set up?
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We are not "They", We are "The others"http://www.servicedept.co.uk -
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radi
Registered User Joined: 22 October 2014 Status: Offline Points: 21 |
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Altec 9444 fan circuit.
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40Hz
Registered User Joined: 31 October 2015 Status: Offline Points: 13 |
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Would it be cheating to put in a temperature controlled PC case fan and place the thermistor wherever yields the right result?
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radi
Registered User Joined: 22 October 2014 Status: Offline Points: 21 |
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^ Nice just add a 12 volt wall wart or bodge in a CheepChyneez® buck converter module and you're done! Some things to note- "quiet" (low rpm) fans spec about half the CFM of higher rpm models. Ball bearing fans are more reliable than fluid (sleeve) bearings, IMO
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