NE555 Circuit Model

Is there an improved version of the NE555 Timer circuit model?
I am trying to design a simple PCB based on this timer.

I draw up the circuit in the Breadboard Window just fine.

However NE555 circuit model, that I am using, taken from the parts bin causes a great deal of upheaval in the Schematic window with rats nest lines all over the window. There are some rats nest lines associated with the NE555 circuit model that will just not go away.

Has anyone else had such problems using the NE555 circuit model in Fritzing?

If you upload the sketch (the .fzz file, upload is 7th icon from the left in the reply menu) I will have a look. It is possible that you have run in to a known (but so far) not reproducible Fritzing bug. The .fzz file should tell me.


Gable Light Breadboard.fzz (44.0 KB)

Indeed you have hit a Fritzing bug. This is the first one (of 5 or 6) that I have seen that clearing all traces doesn’t fix. We think (because we have been unable to reproduce it in the last 5 or 6 years) that it is caused by making incorrect changes in another view which causes routing database corruption. The recommendation is to complete one view (such as breadboard) completely and only then click on the rats nest lines in the other views and route them (and if there are errors found in that process, remove all traces in the view you ware working on and correct the error in the original view!)

Here I clicked a ground connection and all the other ground connections light up yellow. Note that none of the power connections light up yellow.

Here I did the same in breadboard to the power connection with the same result.

Here I switched to schematic and did the same thing (clicked on a ground connection) note that both gnd and vcc light up yellow here indicating a short between power and ground that isn’t showing in breadboard. This is one indication (along with unwanted rats nest lines) of routing database corruption.

To try and fix this without losing the parts placement (and in the past this has worked!) I selected all traces in Routing->Select All traces and hit the delete key to delete them all.

That leaves rats nest lines which are connections in breadboard, so move to breadboard and do the same thing.

Here one complication is that the breadboard provides connections for components mounted on it so I need to unlock and delete the two breadboards to clear all connections.

that produces this with no connections present in breadboard.



in this case (the first time I have seen this!) there are still rats nest lines showing in schematic even though it is showing routing complete (which should mean no rats nest lines) indicating we still have database corruption. The only way I know to fix this is to start a completely new sketch and place and connect all the components in breadboard then switch to schematic and pcb and click on the rats nest lines (making the correction in breadboard if the rats nest line goes to the wrong place!) which is a major pain in the ass, but the only thing I know that works.


Peter: Thank you for all of your help and insight! After I had “invested” four hours of my time on this problem, I thought that maybe it was Fritzing and not me.

I will apply all of the information from your Capcha figures and see what happens.

This is not exactly a problem with intuitive solutions.

Thank you once more.

This is a really ugly bug! As noted I have been chasing it for more than 5 years now, the problem is even with 5 different broken sketches from different people over the years I can not make a series of changes (that I think they did) and cause the problem nothing I have tried causes the problem for me. If we can’t recreate the problem we can’t fix it either. Luckily it is fairly rare, but as you note, it is a pain when it happens. Most of the time deleting all traces will fix the problem leaving the layout intact and only requiring rewiring, but this time even that didn’t work.


Peter: This “Opportunity” in engineering causes Design After Make. At least this is how I view such items. Besides, such problems have taught me new words to describe the situation.

Thank you for your understanding and help.

If and when I get this mess cleaned up, I’ll get back to you.