Hi Ren,

The bigger coils I used are trifilar with the trigger and power wound first in the correct direction. Then on top of that, I wound the 3rd wire in reverse. Actually, I believe John's intended way was to wind all 3 at the same time in the same direction.

It was my misunderstanding and the dot at the bottom showed it was out of phase as in catching the collapse. However, I have seen amazing results doing it my way. If they were wound the same, I'm sure there would be a difference but not sure what.

I don't know all the technical differences between an scr, transistor, etc... all I know is that there is an input and output and the connection is made when a base/gate/trigger receives power. Also, there are differences in switching times, which can be identified on spec sheets...faster the better it seems. SCR seems to be more like a diode with a trigger.

Of course there is the inverse...input and output connection is there unless the trigger receives power to turn off the connection as in a PNP transistor.

I think for practical purposes mechanical/analog is best. You can always cut a piece of copper but you can't always have a 555 at your disposal if the entire electronics industry disappears.

I think you'd have no problem with the 555 circuits. As long as you just connect all the right connections together you got it.