Turn on a fan 1 min every hour

Discussion in 'The Projects Forum' started by BrettO, Aug 13, 2009.

  1. BrettO

    Thread Starter New Member

    Aug 13, 2009
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    I'm working on a little invention. I have a small 5 volt computer fan. It will run off 3 triple A batteries. To conserve energy I need it to only turn on for 1 minute every hour or something close. Lastly the timer/controller needs to be really cheap and really small (no bigger than the size of a AAA Battery). Does any one have an idea what type of "Timer" or "Controller" need? Where I might get one?

    Thank you,
    Brett
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Check post by JPK777. If you want it small, use surface mount parts. Would need more decoding or a 555
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    I'd go with a 4060 on this one, but you'll need transistors to drive it.

    How much electronics background do you have?
     
  4. AlexR

    Well-Known Member

    Jan 16, 2008
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    This would seem to me to be an ideal application one of the smaller micro-controllers like one of PIC10F series (SMD 6pin SOT-23 package).
    The PIC would need no support components other than maybe a transistor/FET to drive the fan and one bypass capacitor.
    It could spend most of its time asleep thereby consuming very little power (somewhere in the order of 10 to 100 of microwatts) while not actually running the fan.
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    Yes you should try a small PIC unit. Even for a hobbyist the investemnt needed for starting development are small. You may pic up cheap programmers on Ebay also. I will recomend PICKIT 2 Starter Kit.
     
  6. jj_alukkas

    Well-Known Member

    Jan 8, 2009
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    Go for a CD4060 with long delay circuit. Will consume abt 5uA. That would be the cheapest idea for you as well as quickest. The size will be abt of a AAA battery, provided you solder it closely packed.
     
  7. BrettO

    Thread Starter New Member

    Aug 13, 2009
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    Thank you for all your help. This is amazing. I don't have much electrical engineering experience. Will all of these options require programing?
     
  8. zoombody

    Member

    Aug 14, 2009
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    How would a 4060 work in this situation? Don't all outputs have a 50% duty cycle? The OP is looking for ~1/60. Also, would the CD4541 be simpler because it has an internal reset, or doesn't it have the right functionality?
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Either should work by adding a 555 for the 1 min; 4060 can also giva approx 1 min. [ 56.2 sec] by decoding 9th-14th stages. Would be helpfull to know fan current. Timing components approx. 1M,470k & .1uF
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    for decoding 4060 use 3X3 in AND[ if there is such], 6 inputs,8192,4096,2048,1024,512,256=1 min.+_.
     
  11. stanford007

    New Member

    Aug 14, 2009
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    I think 555 with a PNP transistor to drive the fan would do teh trick. Compoenet 555, 3 -4 resistors a couple of capacitors, and you should be up and running..
     
  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    007, have you measured leakage of a 3600 uF cap? I am rght now measuring a 3000 uF cap @ 25V and it is holding @ infinity, but at the same time its charging with a 9 V battery in series with 470k, afraid a 1M timing resistor would be swamped; back to drawing board. One 555 for an hour, but would need another for the minute.Hang in there, we need all the help we can get.
     
  13. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Woops!!, stage 11 is not available, would give two 1 min pulses at end of each hr., adding stage 8 [128 ], would give two 1/2 min, 3 min. apart, pulses /hr-OK? CD4073 3 X 3 in AND.
     
  14. AlexR

    Well-Known Member

    Jan 16, 2008
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    Only the micro-controller solution involves any programming so it may not suit you, but if you have any familiarity with micro-controllers (or don't mind learning) then it is the simplest and most efficient way meet your requirements of small size and very low battery drain.
     
  15. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    One min on, 59 off. PNP output transistor selection depends on motor requirements as does R3. All subject to review.
     
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