why the grounded metal case(and should read with optoisolated I/O)? Induced HV transients across the input gates of the avr chip.. takes about 100v/cm2 to damage igfets
and the initial circuit will probably switch a 2n2222A/2n3055 pair to the primary of a GM spark coil(which means at least 25kv..)
And to be more precise I am looking at voltages as high as 50kv ,the X26c first stage voltage for creating ionization paths through clothing and also needed to fire the cartridges
if I dupe for research purposes the multiple flyback HV section from the taser patent papers then I am looking at 50kv in the HV section.. with at least 2 transient inducing spark gaps
although both fortunately are not operating at once.
right now I am looking for a 20ohm 5 watt resistor for the HV section using the GM coil:)(the time machine based design)
and again this is to determine methods and means of handling HV alongside of microprocessors..ie a research project..
fence chargers are a dime a dozen and are not really the point of the exercise.
A fence charger that can sense load and back off to safe levels automatically thats a different matter(and still clip weeds or not depending on humidity levels and load and settable options)
A fence charger that could sense heartrate similar to current taser designs and make its shock nonlethal automatically or no shock at all to humans sensed?? very interesting...and useful
special rules DO apply for handling HV such as the induced transient problem mentioned above.
some of the design principles come from a project found in circuit cellar for an ECM(spark and injectors) for a custom engine design a decade back or so.
ps this is NOT about the best oscillator circuit for the job, this is about again controlling HV with microprocessors.. fence chargers are interesting because of the many HV design issues but are not really the point of the design exercise..and the arduino or mps430(proto board at $4.30? I will be ordering a couple of those for testing to destruction) are simple and easy development environment(s) for the project..