temperature controlled fan speed

Discussion in 'The Projects Forum' started by markosillypig, Aug 21, 2013.

  1. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
    184
    0
    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...arts_Vehicles_CarParts_SM&hash=item35cad4abed
    thanks for any help
    marko
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,036
    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.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,521
    2,369
    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.
     
    Last edited: Aug 21, 2013
  4. markosillypig

    Thread Starter Active Member

    Jul 21, 2008
    184
    0
    any links or schematics would help thanks
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,521
    2,369
    One for a start, ebay 271214914630
    Just Google The LM35 data sheet.
    Max.
     
  6. trader007

    Active Member

    Feb 27, 2010
    222
    19
    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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