temperature controlled fan speed

Thread Starter

markosillypig

Joined Jul 21, 2008
188
hi every one
my quest this month is to find a circuit for my winter heat exchanger.
basically i want the fan to spin slowley as the heat gets hotter i want the fan to spin faster as to cool it down quicker to a set temperature so the hotter it gets the faster it spins
so i'm looking for a circuit or a link so please help if you can the fan is 12v 80 watts
http://www.ebay.co.uk/itm/UNIVERSAL-12-12V-RADIATOR-INTERCOOLER-FAN-WITH-CURVED-FAN-BLADES-CAR-RACE-TRACK-/231036201965?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item35cad4abed
thanks for any help
marko
 

wayneh

Joined Sep 9, 2010
16,102
I'd use LM35 to sense temperature, a voltage-to-duty cycle PWM control, and a MOSFET switch to take the PWM signal and control the fan(s). There are tons of examples all over the 'net since this is the same need that computer fans have - speed in proportion to temperature. A lot of those circuits, though, are not PWM. I'd focus on the ones that are.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
You could check out one of the $5-$10 PWM controllers on ebay and hook up a thermocouple to the analogue input, you may have to add a little bit of interfacing between T.C. & input.
Max.
 
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Thread Starter

markosillypig

Joined Jul 21, 2008
188
I'd use LM35 to sense temperature, a voltage-to-duty cycle PWM control, and a MOSFET switch to take the PWM signal and control the fan(s). There are tons of examples all over the 'net since this is the same need that computer fans have - speed in proportion to temperature. A lot of those circuits, though, are not PWM. I'd focus on the ones that are.
any links or schematics would help thanks
 

trader007

Joined Feb 27, 2010
233
You could check out one of the $5-$10 PWM controllers on ebay and hook up a thermocouple to the analogue input, you may have to add a little bit of interfacing between T.C. & input.
Max.
i just bought one for dimming an led light strip. they work well, however for lights there is a small 'dead' spot on the low side before it comes back at all the way dim, but its no big deal.
 
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