Help With 24V Cooling Fan

Discussion in 'Archived Threads 2001-2004' started by KarlV, Nov 7, 2002.

  1. KarlV

    KarlV Extra

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    I am needing some help locating a 24V fan. I am looking for a replacement fan for my Crown amplifier. The fan that is currently in the amplifier is 120mm X120mm X 25mm, made by Sunon, approx. 80 cfm, and is a loud 44 dBA. I have found a Panaflo with similar air flow, 35 dBA, but is too thick - 38mm. Evercool supposedly makes a fan to fit my needs, but I can only locate vendors with 12V versions, none carry or are willing to pursue obtaining a 24V version for me. Any suggestions would be greatly appreciated!

    Has anyone successfully utilized a 12V fan with 24V supply power utilizing a transformer or other circuit?
     
  2. Isaac C

    Isaac C Stunt Coordinator

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    You've 3 choices:
    1. Use a 24V to 12V DC-Volt reducer module. The module itself might cost more than the new cooling fan; it depends on the module's ampere rating.
    2. Use two 12V cooling fans in series. You could use the other fan on another device on your amp.
    3. Use a resistor in series with the fan to drop the supply voltage to 12V. A suitable resistor would have a minimum resistance of 12V divided by the cooling fan's rated current while its [the resistor's] minimum power rating should be 12V multiplied by the fan's current rating.
    hth [​IMG]
     
  3. Dave Milne

    Dave Milne Supporting Actor

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    Expanding on Issac's option 1... the converter could be as simple as a fixed voltage, positive three-terminal regulator, e.g. LM7812 or LM340-12. These are available for less than a dollar. You will need to find one with a current rating at least equal to fan current and you will most likely need to provide an appropriate heat sink (could be the amp's chassis as long as you provide electrical isolation).

    Edit: Be careful that you don't overload the 24V supply in the Crown (too much current). In general, 12V fans will require twice the current to move the same amount of air. I have no idea how robust the 24V fan power supply in the Crown is...
     
  4. Rory Buszka

    Rory Buszka Supporting Actor

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    why are you replacing this fan? If the fan is thermally-controlled, then you should only be having issues at the amp's full output, and then that shouldn't be very often. The fan you replace this one with might not have the same cooling capability as your Sunon. Another thing: There are designs on the internet for circuits that use an IC and a voltage regulator to turn a non-thermally-controlled fan into a thermally-controlled one. It uses a thermistor on the heat-producing object and you can set your own parameters for the temperature at which the fan runs at its greatest speed and when it should run at its lowest speed using variable potentiometers integrated right into the design. If you're going the voltage-regulated route I suggest you at least look ito this because it gives you a great amount of control, and you can re-set it if you start having the TEMP light come on.
     
  5. Isaac C

    Isaac C Stunt Coordinator

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    Great suggestion Dave! I forgot about those great devices. Consider an LM317 as well, which is an adjustable voltage regulator. You could set the output voltage lower than 12V during, say, winter [​IMG]
     
  6. Rory Buszka

    Rory Buszka Supporting Actor

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    (I just edited my post above to tell about circuits that can turn any fan into a thermally-controlled fan using an LM317. You can go a search for "Thermal Control Circuit" on Google and get computer-enthusiast web sites that have plans for just such a thermal control circuit.)
     
  7. KarlV

    KarlV Extra

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    Thank you for your suggestions. The reason I originally wanted to replace the fan was that when the amplifier is turned on the fan runs at one speed at 44 dBA. With the options you have given me, I can either go with a 12V or make the existing fan variable speed. Not sure which I will do, I will need to do a little research on both options.

    Thanks again.
     
  8. Will Orth

    Will Orth Stunt Coordinator

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    send me a e-mail at [email protected]
    i think i know where to get you any fan you want..
    Will
     
  9. Vince Bray

    Vince Bray Stunt Coordinator

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    I found that Mechatronics (sp?) makes a whole range of 24v fans. I finally found a distributor by picking out the fan I wanted and contacting Mechatronics to find distributors who actually had ordered that part. Soundsl like a hassle, but compared to calling multiple companies to find a weird part, it was very simple. The fan speed control sounds promising too. You'll likely to find that fans that are equivilent to what you have are also nearly as noisy, all though the mechatronics I found was about 6db quieter.
     

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