Hi there
Nothing of importance , Im just finding my feet with Kicad, I use it often to draw schematics for wiring on vehicles, ( its great for that )
But I thought I would give the Simulation a try, So I drew a coil ignition circuit, 12v source, points ( switch) through a transformer ( step up), which, when the current collapses, produces a current in the secondary winding that go through a spark plug cap resistor and a spark plug air gap ( resistor ) to earth, basically the secondary winding is a tank circuit with a capacitor, However I got the sim to run but I really don’t know what values to plug in where, Especially with the transformer. atm I am just making up numbers
Im using Kcad 9 on a linux system
I can up load the file just not sure how ,
Hope someone can help
Kind regards
Stephen
For a car ignition coil (transformer / bobine).
Primary inductance has be low enough so the right amount of energy is stored in the magnetic field in the short time available. (A few ms maybe?)
When the switch opens, the same current wants to keep flowing, or a current though the secondary coil divided by the turns ratio. And to keep the current flowing, the voltage rises to whatever voltage is needed, until either the switch, or the spark plug sparks. The ratio of voltages between the primary and secondary coil will be (approximately) proportional to the turns ratio, but there is voltage drop due to the current.
There is also a capacitor over the primary coil. This reduces the speed at which the voltages rise, so the switch is open further before the voltage get really high. And probably, at the moment the spark plug sparks, it’s impedance is very low, and the capacitor also dumps most of it’s energy in the spark, so you get a stronger spark.
That’s the best I know about ignition coils and spark plugs.
Also, spark gaps are real electronic components used to limit damage due to over voltages. There are probably spice models for these things available.
For the rest: This forum tries to limit itself to help with how KiCad works, and not to projects or electronic theory. But we also want to be friendly towards users, so there is a compromise to be found here.
The easiest way to get started with simulations in KiCad is to search this forum. There are several threads which each post over 30+ simulations that work in KiCad. And probably some of them use transformers too.