I made my own Leyden jar in a bottle filled with salt water. I hammered a nail through the cap and wrapped aluminum foil on the outside. I connected this Leyden jar across my contact point. To my surprise, it actually reduced sparking on the primary side, and made the sparks on the secondary a lot more intense!
Later, I designed an ignition coil driver circuit using a 555 timer for continuous sparks. After a lot of trial and error, and blowing several 555s, this circuit seems to be working reliably.
You could adjust the potentiometers to change the 555’s output waveform, and this also changes the quality of the sparks.
I have also tried connecting two ignition coils (in reverse-parallel configuration) to increase the output voltage. Based on the length of the spark gap and the dielectric breakdown voltage of air, I estimated the voltage to be somewhere around 60,000V! Be very careful when doing these experiments. Contrary to what you may want to believe, 60kV shocks don’t exactly feel pleasant (words of experience). I got lucky. Seriously, be very careful when working with high voltages. Carelessness could be fatal. Don’t get close to the spark gap or to any antenna connected to the transmitter.
