"Cmos, Electric Fence Design"

"FENCER-1"
Created: "Aug 13, 2007"
Updated: "May 1, 2011"

A circuit design, based on a C-mos chip to Drive a Car Ignition Coil.

This is a Very Simple and Efficient Design for an Electric Fence. It puts out a Very high Voltage Current pulse, yet it draws a very small average Current from the battery or supply.


   Click HERE:
See what this Electric Fence caught in Arkansas.

It is 10 feet long and got stuck under the fence. It Died there. Obviously it was someones PET, that got away.


As Accurate as I can Measure, the "AVERAGE Current Draw" varies between: 20 uA at at Slow Pulse setting to about 85 uA at the fast pulse setting.

So Battery life is "Really Good" and this makes a Good Electric Fence.

NOTES:

Due to a High Peak Current Draw, this Fencer will NOT work properly, just running from a Power Adapter or a work-bench power supply.

This Electric Fence Should be powered by a 12 Volt Battery and this battery Should have a Trickle Charger on it. A Small "Solar Panal" would do this quite well. (Occassional Cycle Charging a car battery or Sealed lead acid Battery is not a good idea.)

THE CASE OF THE COIL SHOULD BE CONNECTED TO EITHER GROUND OR THE DIST. TERMINAL. FAILURE TO DO SO, MAY RESULT IN THE CASE BECOMING ELECTRICALLY HOT.

On Some Ignition Coils, the Points Terminal is Marked as "Dist" for Distributor and on some others it is marked as "Neg" or "-"

C2 Determines the duration of the pulse and VR1 determines the number of pulses per second. The Values shown give good Results.

The LED and R4 are Optional. They just show its working.

After assembly of the Circuit board, All Solder Flux Should be Removed from it. Solder Flux CAN Become Conductive in the presence of Moisture and this can result in eventual failure.

Also both the "Circuit Board and Coil Must be Protected from Rain and Snow".

Suitable Insulators must be used on the fence, or Rain will short it out. It Won't damage the circuit if that happens, But it also won't shock anything.

Not much else I can say now, maybe more later.

An Etched and drilled PCB's is Available from me. A Kit of parts/pcb is also available. (Excludes the 12 volt Car Coil).

 The Schematic

 "Circuit Board"

 "Picture overlay".

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Chemelec

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