So far for all of my testing I have used DC voltage charging the cap at what ever rate, or in the case of the car ignition coil, driving it with my function generator. I am thinking about making some sort of auto keyer for it.
http://www.trainelectronics.com/MorseCode/(I like their yard train set)
The plan is to have a programmable 1Hz to 1Khz with a fixed one-shot to drive the ignition coil. I would mount everything, including the battery. The coil driver and would be on the same board. Problem with increasing the voltage is it can create a fair bit of noise which could impact the circuit. I thought about using CMOS gates to generate the timing and hard coding the identifier in diode logic. Basically run it off a higher voltage to improve its margins. It's not like we are dealing with anything fast.
Micro would make more sense. Just a DIP switch with a couple of bits for the modulation frequency (1,100,500 & 1k), 1bit for 5 or 10 WPM, 1bit for auto or manual, and a couple of bits to select an ID message.
Idea would be to make it easier for the FCC (really me) to identify the source of the noise. Right now, I am listening for a "click" sound which makes it difficult to tell if I am just hearing noise or the actual transmitter.