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ARRL Edition

Discussion in 'General Technical Questions and Answers' started by AC6S, Oct 11, 2018.

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  1. AC6S

    AC6S Ham Member QRZ Page

    I understand that some months ago there was an article in QST magazine describing, and offering, a cooling fan circuit board kit that automatically adjusts for temperature variations. A DIY project, except that the circuit board is ready to go.

    I do not keep my QST magazines and am admittedly guilty of not always reading them and I certainly missed this artical. Does anyone know what month it was so I can go online and get the information? Alternatively, simply post the contact information of the person offering the kit here, as long doing so is not a rule violation.

    Appreciate any help. 73.
     
  2. W1VT

    W1VT Ham Member QRZ Page

  3. AC6S

    AC6S Ham Member QRZ Page

    My, that took no time at all. Thank you very much.
     
  4. N3DT

    N3DT Ham Member QRZ Page

    The circuit in the link does not adjust for temperature, it's just a fast start low run circuit the way I read it. Try QST Feb 2018, A Fan Controller for your Classic Radio, Bryce, Mike, WB8VGE
     
    Last edited: Oct 11, 2018
  5. N2EY

    N2EY Premium Subscriber QRZ Page

    If you don't keep your QSTs, you can go to the ARRL website and look at them online.
     
  6. KA8ZAW

    KA8ZAW Premium Subscriber QRZ Page

    You might try your local library. The one in our town keeps copies for years, just ask and they will retrieve anything from storage.
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    I've used a NTC thermistor to provide the temperature input to a comparator that ultimately drove a cooling fan motor. The other comparator input was a variable reference to set the trip point (a manual gauge was used to measure temperature). Positive feedback around the comparator provided hysteresis to prevent the comparator from "hunting". The application was the electric motor that drove the fan and water pump on my racecar. I used a LM311 comparator:
    [​IMG]
    I first characterized the resistance of the thermistor (vehicle water temperature sensor) at cold and the hot points.

    If you want greater accuracy, a LM35 "Precision Centigrade Temperature Sensor" (datasheet) provides 10mV/°C output. The LM34 is the same, except output is 10mV/°F. They're available in various packages for cheep, and you can directly measure temperature w/ a DMM.
     

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