555 Timer getting extremly hot + PWM not working

Discussion in 'Digital Circuit Design' started by GuineaPig123, Aug 27, 2016.

  1. GuineaPig123

    Thread Starter New Member

    Aug 27, 2016
    5
    1
    Hello AAC community,
    I am trying to build a PWM Fan Controller like this one but I can't get it to work. Instead my 555-Timer is getting really hot, the other components not. Have I shorted it somehow? I'll attach my circuit on a breadboard. The "original" circuit can be found on the overclockers site I linked or here.
    (Haven't tried an other 555 yet)
    PWM-Fan-Controller.png

    PWM-Fan-Controller_768x600-h.jpg
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Welcome to AAC
    Check the 555
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Remove the connection on pin 7 (discharge).
    Also move the output signal direct to pin 3 and not via the 1K resistor.

    Bertus
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,654
    632
    Also, do you have a fan that will operate with less than 2 volts? It you are using an NE555 rather than the CMOS LMC555 the positive output looses two diode drops, making the maximum lightly loaded output only 1.8 volts.

    It might be that the motor is drawing a lot of current. Try disconnecting the motor and see whether the '555 still gets hot.
     
  5. GuineaPig123

    Thread Starter New Member

    Aug 27, 2016
    5
    1
    No, my Fan(s) run on a dedicated 12V power supply

    I will try that. Thanks!
     
  6. GuineaPig123

    Thread Starter New Member

    Aug 27, 2016
    5
    1
    Ok, still getting really hot (after like 5-10secs it is almost boiling) even with a different 555
     
  7. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,951
    387
    Wired as per the breadboard diagram, the '555 should not overheat. Check your actual wiring carefully against that diagram, especially the power supply polarity.
     
  8. DickCappels

    Moderator

    Aug 21, 2008
    2,654
    632
    What is the power source for your NE555?
    Would you please post the circuit that the NE555 is driving? <= likely cause of problem
     
  9. GuineaPig123

    Thread Starter New Member

    Aug 27, 2016
    5
    1
    The power source is a 5V DC 1500mA Power supply. I already checked the polarity of that one.

    The circuit that is NE555 is driving is as simple as this
     
  10. GuineaPig123

    Thread Starter New Member

    Aug 27, 2016
    5
    1
    Hm... Tried a third 555-Timer and worked this time... I must have had really bad luck with that. It is not getting hot anymore and I can controll my fan.

    Thanks for all your time and effort!
     
    wayneh likes this.
  11. dannyf

    Well-Known Member

    Sep 13, 2015
    1,811
    362
    electronic parts don't have that kind of failure rate. Something else was/is wrong.
     
  12. Ritalie

    New Member

    Sep 5, 2016
    3
    0
    Were you using the correct 555 timer? They make a CMOS version which has 10 times less power output, but looks the same. It would burn up.
     
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