Ah, I should have said off the bat. It's a Pulsed Electrical Magnetic Field (PEMF) therapy machine. It's a legitimate form of treatment, the FDA has given that technology the OK to be used for treating brain cancer even.
I'll be careful not to erase my brain with it. lol.
My halfway working version of the machine stuck on rapid pulse mode was somewhat useful for my chronic headache, I just want the pulses to get in deeper with a longer charge.
I bought an SCR with good voltage specs that has a 40 mA gate trigger that should work with the circuit. Also the designer said it needs a 1M resistor from the gate to ground.
I've been careful to discharge the caps with a high watt 10k resistor before working on it.
Thank you all for your help and your concern.
A study on PEMF treating cancer, if interested:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5119968/ "Mice exposed for 60 and 180 min daily showed a 30% and 70% tumor reduction, respectively, at week 4, if compared to baseline." Pretty promising stuff.
I know using a rando PEMF circuit to treat a chronic headache is a bit off the beaten path but I was really pressed for solutions. Neurologist didn't do anything for it.
I'm not saying I have brain cancer, but it does facilitate deep tissue healing.