🚀 go-pugleaf

For those interested in AC modem systems, through bitter experience, 
I'd like to make a couple of suggestions
1 : only top quality X2 rated caps for coupling fron the tank coil to 
the mains.
2 : Beware of the TOKO AO42 style coupling coils - they may be fine 
in 115 volt territory, but ive had one go down with spectacular results
(bright flash out the little window of a 8751 - after which it ceased 
to compute!) with 230 volt systems - a postmortem revealed that the 
enamel on the wire is the ONLY thing that separates primary and secondary.
3 : Remember the fast zener on the driving side of the tank - the resonant 
spikes can get spectacular.
4 : Dont forget the Z-mov.
Other than that, these sorts of units work real well, especially when 
you use micros instead of dumb UARTS, thus gaining error control etc.