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

On 06/14/2014 05:51 AM, 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


If you do you will be in violation of several laws regarding harmful
interference.

On Sat, 14 Jun 2014 05:51:20 -0700 (PDT),
wrote:

MY friend would like me to help him build a cheap electric fence.

Please make an effort to reduce the amount of EMI/RFI to tolerable
limits.

I like the title "poor mans electric fence". Yeah, I suspect you'll
probably become poor after the doctors treat you for electric shock.
Please remember that you have but one life to give for your
profession.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 06/14/2014 6:26 AM, dave wrote:
On 06/14/2014 05:51 AM, 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



If you do you will be in violation of several laws regarding harmful
interference.

Indeed, the FCC (if in the USA) will pay you a surprise visit for
broadcasting without a licence, along with your local HAM radio folks,
Civil and Military Aviation folks, possibly National Guard and anyone
else (neighbours with pitchforks and burning torches) who your broadband
long wave RF noise generator annoys...

Look up "Spark Gap Transmitter Interference" on your favourite search
engine.

http://radiohax.wikispaces.com/Spark+gap+transmitter

John ;-#)#

--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Saturday, June 14, 2014 9:26:41 AM UTC-4, dave wrote:
On 06/14/2014 05:51 AM, 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





If you do you will be in violation of several laws regarding harmful

interference.

Well then I imagine that every rancher with an electric fence must be repeating Marconi's experiment as well. And what about the computers in the area that break the squelch on my low band radio in my truck as I drive past the same houses. And not to mention those infernal speed controlers and light dimmers that raise hell with AM radio. MJy friend is just trying to keep coons out of his garden. How do these guys get away withit. Lenny

In article ,
wrote:

If you do you will be in violation of several laws regarding harmful
interference.

Well then I imagine that every rancher with an electric fence must be
repeating Marconi's experiment as well. And what about the computers in
the area that break the squelch on my low band radio in my truck as I
drive past the same houses. And not to mention those infernal speed
controlers and light dimmers that raise hell with AM radio. MJy friend
is just trying to keep coons out of his garden. How do these guys get
away withit. Lenny

They don't use a spark-based generator.

I looked at a few of the schematics out there on the net, and a lot of
them seem to use a low-voltage astable multivibrator (e.g. a 555) to
trigger a triac, which dumps a pulse of chrarge from a capacitor
(e.g. a couple of hundred volts) into the primary of a step-up
coil. The coil then drives the fence wire.

This approach would (I think) result in the rising and falling edges
of the current pulse into the primary not being incredibly fast... the
rising edge would be limited by the coil inductance, and the falling
edge would result from the stored-up charge in the cap damping down -
there's be some ringing to the latter, but not the sharp edges you'd
see from a spark gap. Hence, a lower bandwidth and less (or no) RF
interference.

Commercial cow fences usually seem to pulse once a second or so - it's
not a constant buzz. It's enough to displease the cows (and probably
deer as well), but it's not continuous enough to risk that somebody
will grab the wire and find themselves unable to let go (which would
be a real risk if you just let a vibrator drive a coil and keep the
wire energized all of the time).

People *do* get in trouble with the FCC over electric-fence
chargers, if the chargers are badly designed and do result in RFI.
The fines for failing to correct such sources of interference can be
quite stiff.

On 6/14/2014 9:26 PM, David Platt wrote:
In article ,
wrote:

If you do you will be in violation of several laws regarding harmful
interference.

Well then I imagine that every rancher with an electric fence must be
repeating Marconi's experiment as well. And what about the computers in
the area that break the squelch on my low band radio in my truck as I
drive past the same houses. And not to mention those infernal speed
controlers and light dimmers that raise hell with AM radio. MJy friend
is just trying to keep coons out of his garden. How do these guys get
away withit. Lenny

They don't use a spark-based generator.

I looked at a few of the schematics out there on the net, and a lot of
them seem to use a low-voltage astable multivibrator (e.g. a 555) to
trigger a triac, which dumps a pulse of chrarge from a capacitor
(e.g. a couple of hundred volts) into the primary of a step-up
coil. The coil then drives the fence wire.

This approach would (I think) result in the rising and falling edges
of the current pulse into the primary not being incredibly fast... the
rising edge would be limited by the coil inductance, and the falling
edge would result from the stored-up charge in the cap damping down -
there's be some ringing to the latter, but not the sharp edges you'd
see from a spark gap. Hence, a lower bandwidth and less (or no) RF
interference.

Commercial cow fences usually seem to pulse once a second or so - it's
not a constant buzz. It's enough to displease the cows (and probably
deer as well), but it's not continuous enough to risk that somebody
will grab the wire and find themselves unable to let go (which would
be a real risk if you just let a vibrator drive a coil and keep the
wire energized all of the time).

People *do* get in trouble with the FCC over electric-fence
chargers, if the chargers are badly designed and do result in RFI.
The fines for failing to correct such sources of interference can be
quite stiff.



Harbor Freight will sell you a solar powered fence charger for $66
less 20 or 25% coupon.
Older I get, the more I shy away from "helping" someone do something
that may cause someone to "claim" they were harmed.
Just not worth all the legal hassles you can get into.

On 6/14/2014 11:47 PM, mike wrote:



Harbor Freight will sell you a solar powered fence charger for $66
less 20 or 25% coupon.
Older I get, the more I shy away from "helping" someone do something
that may cause someone to "claim" they were harmed.
Just not worth all the legal hassles you can get into.
I thought one of the HF chargers would be just the thing for a deer
fence around the garden. Worked great till winter came. Then the amount
of daylight was not enough to recharge the battery for all night use and
eventually the whole thing became useless.

Just the solar charger and battery now work great to power the trail
camera for long term use. Disconnected the charger portion.

Paul

In article ,
says...

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

Make a capacitor discharge into a car coil via an scr.

Use a pulsed DC to charge the cap at a high rate so they'll be
a gap in the supply to the cap. Use a timer to trigger the
scr which shorts this cap to ground.

The pulse being in the DC to charge it up has a void of no current in
the off duty part of the pulse (Diode) and allows the SCR to turn off so
the cycle can repeat itself.

if you're doing all of this from low voltage you can use a 556 timer,
this would be the DUAL version. One timer is used as a pulse generator
to charge the cap while the other would be the long duration
pulse to supply a very short duty pulse with long off time.

Some designs use the falling edge of the charging pulse to charge up
a cap on for the trigger pulse to the scr so that it's asynchronous and
that circuit will discharge that cap for the next whack on the cattle's
body!


Have fun.

Jamie

Maynard A. Philbrook Jr. wrote:
In article ,
says...

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

Make a capacitor discharge into a car coil via an scr.

Use a pulsed DC to charge the cap at a high rate so they'll be
a gap in the supply to the cap. Use a timer to trigger the
scr which shorts this cap to ground.

The pulse being in the DC to charge it up has a void of no current in
the off duty part of the pulse (Diode) and allows the SCR to turn off
so
the cycle can repeat itself.

if you're doing all of this from low voltage you can use a 556 timer,
this would be the DUAL version. One timer is used as a pulse generator
to charge the cap while the other would be the long duration
pulse to supply a very short duty pulse with long off time.

Some designs use the falling edge of the charging pulse to charge up
a cap on for the trigger pulse to the scr so that it's asynchronous
and
that circuit will discharge that cap for the next whack on the
cattle's
body!


Have fun.

Jamie

Here are links to a couple of electric fence projects, complete with PCB
layouts:
http://chemelec.com/Projects/Fencer-1/Fencer-1.htm
http://chemelec.com/Projects/Fencer-2/Fencer-2.htm

Dave M

On 06/15/2014 04:15 PM, Maynard A. Philbrook Jr. wrote:
In article ,
says...

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

Make a capacitor discharge into a car coil via an scr.

Use a pulsed DC to charge the cap at a high rate so they'll be
a gap in the supply to the cap. Use a timer to trigger the
scr which shorts this cap to ground.

The pulse being in the DC to charge it up has a void of no current in
the off duty part of the pulse (Diode) and allows the SCR to turn off so
the cycle can repeat itself.

if you're doing all of this from low voltage you can use a 556 timer,
this would be the DUAL version. One timer is used as a pulse generator
to charge the cap while the other would be the long duration
pulse to supply a very short duty pulse with long off time.

Some designs use the falling edge of the charging pulse to charge up
a cap on for the trigger pulse to the scr so that it's asynchronous and
that circuit will discharge that cap for the next whack on the cattle's
body!


Have fun.

Jamie


Why not just use a flyback transformer? Do cars even have coils these
days? There are tiny flybacks on each sparkplug wire. Run by computers,
not distributors. More efficient. Babbling.

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

Well, I was trying to keep it simple. And that's where the spark gap gizmo came in. Lenny

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".

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

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

Was this a 6 or 12 volt coil? And I'm assuming then that you're talking about an automotive ignition coil and that the current through the switch wasn't that great? Lenny

On 06/14/2014 04:44 PM, Jeff Liebermann wrote:


I like the title "poor mans electric fence". Yeah, I suspect you'll
probably become poor after the doctors treat you for electric shock.

Yeah, especially if they are Jewish doctors.

Please remember that you have but one life to give for your
profession.


It's better to give that one life to my profession than die in some
raghead country fighting another imperialistic war for US/Israel.