galvanic isolation for lm555

Hi guys I am trying to implement galvanic isolation for my lm555 square wave generator. I am designing a marx generator so this is essential. I am new with transformers, at the moment all I want to get is the same square wave at the secondary side of the transformer but LTSpice doesn't even want to run it. Can anyone give me some advice? Am I missing any components? Cheers. Here is the circuit i am trying. The square wave is at around 8kHz

This is the output across the resistor after grounding the secondary side.

• What error are you getting? What happens if you connect a ground symbol to one of the nodes on the secondary side?(SPICE doesn't much like fully isolated circuits) Mar 28, 2018 at 3:57
• @ThePhoton, the problem is that i want to have that side of the transformer isolated, so connecting the same ground there wouldn't be an option for me. I tried it and it does give a square wave it only gives positive and negative peaks Mar 28, 2018 at 4:05
• It can be isolated in real life but not in the simulation. SPICE is simply not capable of modeling true isolation, because there is no single solution to the circuit when there is isolation since the secondary could be offset by an arbitrary DC voltage. Mar 28, 2018 at 4:07
• Anyway if you want an answer you will need to tell us what error you got, or how the results were different from what you expected (and why you think they're incorrect). We can't read your mind so you need to share all the relevant information about your problem with us in writing. Mar 28, 2018 at 4:08
• Maybe a few femtofarad capacitor that will simulate the capacitive coupling between the two sides of the transformer could help Spice? Mar 28, 2018 at 5:10

It looks like your square wave is about 5 kHz and so at 5 kHz, the 100 nH primary has an impedance of $2\pi\times 5000 \times 0.1\text{E-6}$ = 0.00314 ohms.