oscilator circuit

Thread Starter


Joined Dec 3, 2011
i am actually trying to achieve probe lighting of an aircraft. so as a start i wanted to have a probe blinking at 75 every 60s. so i used a 555 timer with resistors and capacitor to achieve it. my problem right now is that the pulse rate is not being constant, around about 20-40s the probe starts to link even more faster i don't understand why this is happening. hope you all could help me with this. Thanks.

i have actually attached the circuit diagram as could not upload the whole multisim.



Joined Feb 12, 2009
my problem right now is that the pulse rate is not being constant
Do you mean in the real thing - after you have built it, or in the simulation?

If in the real thing I would look at changes in the supply voltage (under load) or temperature effects.

If in simulation - not sure! Your computer?


Joined Dec 20, 2007
Multisim does not know if it is coming or going.
Use a more modern sim program that works properly.

Most of us use the free sim program LTspice IV from Linear Technology.
Old teachers use old Multisim.