A SHOCKING FENCE TALE
By Norris Chambers
the late thirties a thing called “electric fence” began to get popular among
those farmers who were able to buy one. They used a six volt automobile battery
for power. The battery could be charged in a number of ways – a wind charger, a
gasoline engine with a generator, by swapping it with one in a car or tractor
or taking it to a service station with a battery charger. The little machines
didn’t require much power and a battery charge would last for several days.
first chance we got Clifton
and I removed the cover of one and looked to see how it worked. It was pretty
simple. There was a rather large hair spring on the same shaft as a little
flywheel with a metal tab on the shaft and an electromagnet that pulled it
against the spring when electricity actuated the magnet. The spring pulled the shaft and wheel back
toward the magnet and just before it touched the magnet it hit a switch that
turned the power on that operated the electromagnet. The magnet pulled the
wheel around again, breaking the connection that the switch provided. Then the
spring eventually stopped the rotation of the wheel and it came back, repeating
the process. This process continued at an adjustable rate of 1 to 4 seconds
between contacts. Each time the switch connected the magnet and moved the wheel
it passed current through a winding on a spark coil and a high voltage was
applied to the one wire that served as a fence.
grounded, or negative, side of the fence was connected to a metal rod driven
into the ground. The output of the fencer was connected to a single wire that
was mounted on insulators and served as the fence. The height above ground that
the wire was strung depended on the type of animals that were to be confined by
it. For hogs it had to be very low; perhaps ten or twelve inches. For cattle
about three feet and for horses about four.
time the switch closed an electric charge was applied to the fence wire and any
animal touching it received a powerful shock. Any kind of bare wire could be
used for the fence. Regular barbed fencing wire worked well. Before any animals
were put in an area using the electric fence they were placed in a training pen
with the electric wire being the only fence. A few attempts to crawl under the
wire soon taught them not to touch a wire. Hogs learned quicker than any
animal. Horses and goats, or sheep, were fast learners. Cows were the slowest
learners but when they learned they remembered well. There was one problem. The
fencers cost more than many farmers could afford.
I had just opened my country radio shop and my
electronic training convinced me that I could build a cheaper fencer that would
and I bypassed the blacksmith shop and went to my crude radio shop to see what
we could do. Instead of the complicated spring and flywheel to give the
electric pulses we got the idea of a marble rolling up an incline and rolling
back down to actuate the switch. For the magnet and coil we substituted an old
Model T Ford ignition coil. It already had a magnet core and vibrating points.
All we had to do was reposition the points and find a metal tube and large
marble (the final model used a steel ball since it was heavier) and arranged
them so the coil pulled the arm and kicked the ball up the tube, which was
mounted on an incline, and repeated the action when it rolled back down. When
the switch was closed for a very short time it sent a spark from the coil to
the fence wire and several thousand volts was applied for animal discouragement.
The idea worked great. All we had to do to set the rate of electric pulses was
raise or lower the incline of the pipe.
had a machine that worked even better than the bought ones because the ignition
coil was stronger than the ones in the manufactured machines. Model T coils
were available from wrecking yards for practically nothing and steel balls were
everywhere around oil wells. The repair kits for the pump overhauls came with
new balls and the old ones were thrown away. They were free for picking up and
cleaning. There was very little cost involved in building the fencers. We had a
winner! We sold dozens of our machines to farmers for eight dollars. The
store-bought machines were at least twenty dollars.
we had fun building them. If you’ve never built an electric fencer you don’t
know how much fun you have missed! Maybe you ought to build one!