On 6/17/2014 9:45 AM, wrote:
On Saturday, June 14, 2014 8:51:20 AM UTC-4, wrote:
MY friend would like me to help him build a cheap electric fence. I found lots of designs, and of course we could go solid state but the simplicity of this one really intrigues me.

I showed him the schematic and he questioned if the repeated opening and closing of the flasher points used in this application would quickly burn them out. I was thinking that in spite of the inductive component, the load of the coil would be much less than the load imposed by a lighting circuit. So I thought that combined with the correct capacitor and perhaps the addition of a small snubber circuit (a small resistor in series with the capacitor) would cut down on the sparking. Perhaps I'm way off base here. Does anyone have any opinions on this or has anyone ever done this? This uses a standard automotive ignition coil. Thanks, Lenny



https://www.google.com/search?q=home...2F%3B822%3B691

Aside from the interference factor as already mentioned I was wondering (just from a hypothetical point of view) if anyone would like to comment on my original Question about the flasher points and snubber circuit as stated below?

Lenny

"I showed him the schematic and he questioned if the repeated opening and closing of the flasher points used in this application would quickly burn them out. I was thinking that in spite of the inductive component, the load of the coil would be much less than the load imposed by a lighting circuit. So I thought that combined with the correct capacitor and perhaps the addition of a small snubber circuit (a small resistor in series with the capacitor) would cut down on the sparking. Perhaps I'm way off base here. Does anyone have any opinions on this or has anyone ever done this? This uses a standard automotive ignition coil".

Before solid state fence chargers, many used an interrupter like the an
automotive turn signal interrupter. They were exposed on the front of
the box so they could be replaced.

The most reliable fence charger was one that came with the 132 acre
Dairy farm Dad purchased in 1957. It had a motor that rocked a mercury
switch back and forth to supply power to a transformer that energized
the fence. You could build a similar unit.

Paul