Here's my take on a simple, low-power fencer using a ignition coil for the output.
The CD4093 Schmitt trigger gates are configured as a 1Hz PWM relaxation oscillator set for a low duty-cycle
POT U5 adjusts the pulse-width which affects the stored inductive energy and thus the output voltage as determined by the fence wire load capacitance.
The coil primary peak voltage is limited by zener D4 to 100V, giving a maximum output voltage of 10kV from a standard 100:1 ignition coil.

The LTspice simulation shows that the average current drawn will vary from about 0.1Ah to 1Ah per day, depending upon the setting of U5.

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Crutschow I'm looking for a super simple basic 12v fence charger. Could you please point me in the right direction. Thanks

Mod: link to old thread
https://forum.allaboutcircuits.com/threads/lets-talk-about-fence-chargers.138483/post-1624770

 

Crutschow I'm looking for a super simple basic 12v fence charger. Could you please point me in the right direction. Thanks

Can't get much simpler than the one I posted.
Just change the 6V to a 12V ignition coil.

 

Ticks me off at myself I got thisdone so lae but schematic ar forever...

You don't want CR1, as the will absorb the stored inductive energy and kill the flyback voltage
The flyback output voltage equals the flyback voltage at Q2's collector time the coil turns ratio.
For a typical 100:1 ignition coil ratio, the output would only be 1200V with the diode limiting the collector voltage to 12V.

To protect Q2 you can put a Zener or a small capacitor from Q2's collector to common.
A 100V Zener diode would give a 10kV pulse at the output, which is a good value for a fencer.

 

Can't get much simpler than the one I posted.
Just change the 6V to a 12V ignition coil.

I'm not familiar with this CD4039. Looks simple enough. So if I change VDD to 12v it shouldn't hurt the 4039 correct?

 

I'm not familiar with this CD4039. Looks simple enough. So if I change VDD to 12v it shouldn't hurt the 4039 correct?

Correct.

 

Use a wet cell car battery, a turn signal flasher, a spark coil, and possibly a half ohm ballast resistor. ALL IN SERIES. The flasher must be a current operated one, not a voltage driven flasher.

 

Correct.

Crutschow, I made this only I used an IRF540N instead of the FDP2532 and it continues to fry both the mosfet and CD4093. Will the FDP2532 prevent this from happening?

 

I used an IRF540N instead of the FDP2532

Why did you replace a MOSFET rated for 150V with one rated for only 100V, and still expect it to work?

Don't know why the CD4093 failed.
Place a 100uF capacitor in parallel with a 100nF capacitor directly across the power to ground pins on the CD4093 and see if that helps.

 

Why did you replace a MOSFET rated for 150V with one rated for only 100V, and still expect it to work?

Don't know why the CD4093 failed.
Place a 100uF capacitor in parallel with a 100nF capacitor directly across the power to ground pins on the CD4093 and see if that helps.

I forgot to order the 2532 and all I had close was the 540. It works for 1 spark before burning up the MOSFET. Ill try the caps and get the correct MOSFET. Thanks

 

The reason a CMOS device controlling a MOSFET device will be damaged when the mosfet fails is because a failed mosfet often includes a gate to source short circuit, at least for a brief time period.