555 Timer getting extremly hot + PWM not working

Thread Starter

GuineaPig123

Joined Aug 27, 2016
9
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
 

bertus

Joined Apr 5, 2008
22,290
Hello,

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

Bertus
 

DickCappels

Joined Aug 21, 2008
10,232
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.
 

AlbertHall

Joined Jun 4, 2014
12,385
Wired as per the breadboard diagram, the '555 should not overheat. Check your actual wiring carefully against that diagram, especially the power supply polarity.
 

Thread Starter

GuineaPig123

Joined Aug 27, 2016
9
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!
 

Ritalie

Joined Sep 5, 2016
4
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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