# 555 Timer Circuit Simulation Generates an Error

I simulated the circuit below:

The expected output is a 50% duty cycle 40 kHz square wave but the simulator (MultiSim) generates an error and doesn't compile. The error message is as follows:

"A simulation error has occurred. Would you like to run the Convergence Assistant to attempt to resolve this problem automatically?"

I ran the Convergence Assistant and that didn't solve anything.

Any ideas why this might be the case?

• I wish I could help you. But it's MultiSim. What else do you need to know? I have a fully licensed version, still sitting in its box with the shrink-wrap still around it (but opened.) I fired up that puppy, ran some circuits through it, quickly stuffed the software back into the box and put it on the bookshelf. Tried to make them take it back, but got too much grief about it and instead just shelved it, permanently. It's been a few years. But I assume it remains the same garbage it was back then. If anyone wants my copy of the stupid thing, feel free to ask. I won't use it. – jonk Jul 2 '18 at 3:37
• You must provide us with the complete, verbatim error message if there is to be any hope of helping you. – Elliot Alderson Jul 2 '18 at 11:15
• @jonk can you maybe suggest me a better software? I didn't purchase the Multisim license. I am running it on the evaluation mode. I have around 30 days left in the evaluation mode. I've previously tried Orcad Capture too and it wasn't very user friendly but I am open to suggestions. – csg Jul 2 '18 at 14:56
• @ElliotAlderson see my edit. It is a very vague message, I am afraid. – csg Jul 2 '18 at 15:02
• The error message helps a lot. It means that the simulation tried to start so there weren't any fundamental problems with the schematic. I suggest you start with a simpler circuit, maybe just a voltage divider, and work your way up. Also, 10$\Omega$ seems like a very low resistor value to use with a 555. What kind of diode is D1? – Elliot Alderson Jul 2 '18 at 15:14