I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

--
MikeW

Please no Danger Net Nanny replies :-)

"MikeW" wrote in message
.com...
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM
MikeW


might be almost the same as a camera flash circuit. maybe you can hack a
small disposable jobbie?

On Mon, 20 Feb 2006 15:43:08 GMT, MikeW wrote:

I need to put a small elec fence around the Veg patch this year
What are you trying to keep out?

And I was thinking of making the energiser (using 12v Batt) myself
Get a 12V coil from an old car, and something to interrupt the
primary.

--
Nigel M

MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

No circuits, but plenty of electric fence energizers on ebay.
--
Sir Benjamin Middlethwaite

Nigel Molesworth, : wrote:
On Mon, 20 Feb 2006 15:43:08 GMT, MikeW wrote:

I need to put a small elec fence around the Veg patch this year
What are you trying to keep out?

And I was thinking of making the energiser (using 12v Batt) myself

Get a 12V coil from an old car,

Yes that's the easy bit

and something to interrupt the
primary.

This is the bit I need the help with ;-(



--
MikeW

In article ,
Nigel Molesworth wrote:
I need to put a small elec fence around the Veg patch this year

What are you trying to keep out?

And I was thinking of making the energiser (using 12v Batt) myself

Get a 12V coil from an old car, and something to interrupt the
primary.

Sounds kewl. You put a push button by the fence and ask the animal or
whatever to push it before touching the fence.

--
*My designated driver drove me to drink

Dave Plowman London SW
To e-mail, change noise into sound.

MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

Old gas cooker igniter module,...bugger that hurt :-)
--
Sir Benjamin Middlethwaite

MikeW wrote:

and something to interrupt the
primary.

This is the bit I need the help with ;-(

A DPDT relay. Use one pole to get the relay to click on/off (by
connecting the coil in series with the n/c), and the other pole to
switch your primary. You'll need to put a large-ish capacitor across the
relay coil to slow down the clicking, once every couple of seconds is
about right.


--
Grunff

Dave Plowman (News) wrote:
In article ,
Nigel Molesworth wrote:
I need to put a small elec fence around the Veg patch this year

What are you trying to keep out?

And I was thinking of making the energiser (using 12v Batt) myself

Get a 12V coil from an old car, and something to interrupt the
primary.

Sounds kewl. You put a push button by the fence and ask the animal or
whatever to push it before touching the fence.

pmsl
--
Sir Benjamin Middlethwaite

MikeW wrote:
Nigel Molesworth, : wrote:
On Mon, 20 Feb 2006 15:43:08 GMT, MikeW wrote:

I need to put a small elec fence around the Veg patch this year
What are you trying to keep out?

And I was thinking of making the energiser (using 12v Batt) myself

Get a 12V coil from an old car,

Yes that's the easy bit

and something to interrupt the
primary.

This is the bit I need the help with ;-(

Movement detector of a security lamp. :-)

--
Sir Benjamin Middlethwaite

The3rd Earl Of Derby, : wrote:
MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

No circuits, but plenty of electric fence energizers on ebay.

Yes but at around £50
I should be able to make one for nought

--
MikeW

On Mon, 20 Feb 2006 16:21:41 +0000, Grunff wrote:

MikeW wrote:

and something to interrupt the
primary.

This is the bit I need the help with ;-(

A DPDT relay. Use one pole to get the relay to click on/off (by
connecting the coil in series with the n/c), and the other pole to
switch your primary. You'll need to put a large-ish capacitor across the
relay coil to slow down the clicking, once every couple of seconds is
about right.


Something to prevent pitting and destruction of the relay contacts?

I wonder about the RFI aspects of all of this as well. Do commercial
units have relays or semiconductor switching, I wonder?

Although this isn't quite in the league of Tesla machines able to
compete with North Hessary Tor, a relay banging away into a coil is
likely to generate enough RF to be a nuisance in populated places.


--

..andy

On Mon, 20 Feb 2006 16:30:49 +0000, Andy Hall
wrote:

On Mon, 20 Feb 2006 16:21:41 +0000, Grunff wrote:

MikeW wrote:

and something to interrupt the
primary.

This is the bit I need the help with ;-(

A DPDT relay. Use one pole to get the relay to click on/off (by
connecting the coil in series with the n/c), and the other pole to
switch your primary. You'll need to put a large-ish capacitor across the
relay coil to slow down the clicking, once every couple of seconds is
about right.


Something to prevent pitting and destruction of the relay contacts?

Condenser from a points based ignition system should be fine. You
could probably also find the relay in the scrap yard along with the
coil and battery.

I wonder about the RFI aspects of all of this as well. Do commercial
units have relays or semiconductor switching, I wonder?

Old ones were relays..new ones semiconductor.

In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

sponix

Andy Hall wrote:

Something to prevent pitting and destruction of the relay contacts?

Yes, that wouldn't be a bad idea - another cap across the relay contacts
switching the coil - in fact, a car ignition cap (condensor) would be
perfect.


I wonder about the RFI aspects of all of this as well. Do commercial
units have relays or semiconductor switching, I wonder?

We've had both types. Strangely, the relay ones last quite a bit longer.
Poor heatsinking on the switching semiconductor I suspect.


Although this isn't quite in the league of Tesla machines able to
compete with North Hessary Tor, a relay banging away into a coil is
likely to generate enough RF to be a nuisance in populated places.

The capacitor should bring the level down to car-emissions levels I'd
have thought.


--
Grunff

Grunff, : wrote:
MikeW wrote:

and something to interrupt the
primary.

This is the bit I need the help with ;-(

A DPDT relay. Use one pole to get the relay to click on/off

Thanks But
I think spark gap transmitter's have been banned for some time ;-(


--
MikeW

On Mon, 20 Feb 2006 16:37:13 GMT, (Sponix) wrote:

In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

Something like this but with a DPDT relay instead of the switch:

http://www.kronjaeger.com/hv/hv/src/ign/ignition1.png

MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

Take the module of one of these...
http://tinyurl.com/mov7c
As they have a time limiter for the lenght of time the lamp is lit.
A relay,12v battery, and the car ignition coil.
I'm assuming(never opend one up)the PIR will have +&- and a triggering
wire.
--
Sir Benjamin Middlethwaite

MikeW wrote:

A DPDT relay. Use one pole to get the relay to click on/off

Thanks But
I think spark gap transmitter's have been banned for some time ;-(


All you'd be doing is re-creating a non-electronic car ignition system.
With a capacitor across the relay contacts, RF emissions should be very
reasonable.


--
Grunff

Grunff, : wrote:
MikeW wrote:

A DPDT relay. Use one pole to get the relay to click on/off

Thanks But
I think spark gap transmitter's have been banned for some time ;-(


All you'd be doing is re-creating a non-electronic car ignition system.
With a capacitor across the relay contacts, RF emissions should be very
reasonable.


Yes you are quit correct
that was a case of me opening mouth before engaging brain.
I was really looking for a semiconductor type circuit but if all else
fails I will try the relay option
Thanks

--
MikeW

MikeW wrote:

Yes you are quit correct
that was a case of me opening mouth before engaging brain.
I was really looking for a semiconductor type circuit but if all else
fails I will try the relay option

That's easy - use a 2N3055 transistor to drive your coil. Use a 555 to
switch the 3055. Need more details, or does that make sense?

--
Grunff

MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.

I've done this with your 12V battery, ignition coil, flasher
unit, and a capacitor.

Chris Bacon wrote:
MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.

I've done this with your 12V battery, ignition coil, flasher
unit, and a capacitor.

The flasher unit off a car, obviously. ISTR the capacitor came out
of a fluorescent tube fitting, dunno whether a car one would be OK,
you could try it.

"MikeW" wrote in message
.com...
Grunff, : wrote:
MikeW wrote:

A DPDT relay. Use one pole to get the relay to click on/off

Thanks But
I think spark gap transmitter's have been banned for some time
;-(


All you'd be doing is re-creating a non-electronic car ignition
system.
With a capacitor across the relay contacts, RF emissions should be
very
reasonable.


Yes you are quit correct
that was a case of me opening mouth before engaging brain.
I was really looking for a semiconductor type circuit but if all
else
fails I will try the relay option
Thanks

--
MikeW

I made one to keep foxes at bay using a Maplins 'ignition amplier' kit
and a normal ignition coil. The 'ignition amplifier' was driven by
another Maplin kit indended for delayed wipers. Works very well though
I had to change the capacitor values to get short pulses at about half
second repetitions

AWEM

MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

My effort, modifications can be implemented, any comments?
http://www.20xx20.myby.co.uk/Energiser.jpg

When little rabbits pass by the PIR it triggers the energiser.
--
Sir Benjamin Middlethwaite

The3rd Earl Of Derby wrote:

oops! no negative connected to coil
negative from coil should link to trigger side of relay

http://www.20xx20.myby.co.uk/Energiser.jpg

When little rabbits pass by the PIR it triggers the energiser.

--
Sir Benjamin Middlethwaite

Grunff, : wrote:
MikeW wrote:

Yes you are quit correct
that was a case of me opening mouth before engaging brain.
I was really looking for a semiconductor type circuit but if all else
fails I will try the relay option

That's easy - use a 2N3055 transistor to drive your coil. Use a 555 to
switch the 3055. Need more details, or does that make sense?



That's the type of thing I was considering
Retail energisers seem to run at about 500ma but a cars HT coil seem to
take 2amp (input)
So I was wondering what was inside the black box to conserve power.

--
MikeW

In article ,
Sponix wrote:
In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

Car ignition systems have short HT leads usually made of a resistive
material to cut down RFI. And the whole lot (usually) shielded by grounded
metalwork. Think the average fence might just act like an aerial...

--
*He who dies with the most toys is, nonetheless, dead.

Dave Plowman London SW
To e-mail, change noise into sound.

MikeW wrote:

That's the type of thing I was considering
Retail energisers seem to run at about 500ma but a cars HT coil seem to
take 2amp (input)
So I was wondering what was inside the black box to conserve power.


They don't use car ignition coils, they use much smaller custom
transformers.

You can wind your own using a TV flyback secondary, but flybacks are
quite hard to get hold of these days.

--
Grunff

Dave Plowman (News), : wrote:
In article ,
Sponix wrote:
In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

Car ignition systems have short HT leads usually made of a resistive
material to cut down RFI. And the whole lot (usually) shielded by grounded
metalwork. Think the average fence might just act like an aerial...



But with an elec fence there is no spark and hence no current flowing so
no RFI
Until something completes the circuit and gets Zapped.


I think

--
MikeW

On Mon, 20 Feb 2006 17:22:40 GMT, "The3rd Earl Of Derby"
wrote:

The3rd Earl Of Derby wrote:

oops! no negative connected to coil
negative from coil should link to trigger side of relay

http://www.20xx20.myby.co.uk/Energiser.jpg

When little rabbits pass by the PIR it triggers the energiser.

I've always used old car batteries (one duff cell) for electric fences
- they last weeks between charges.

Without looking up the details they usually give about 5kV pulses of
0.1 - 1 Joules at abou 0.5 Hz.

There is a BS standard !

You can get some low electric netting to use against rabbits or use 2
or 3 strands of wire close together.

Robert

"MikeW" wrote in message
.com...
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM



You should be able to produce something with a UJT circuit but personally I
wouldnt bother. Go around the car boot sales and see whats on offer. Over
the last few years I have bought two for a fiver (uses four D cells) and
eight quid (uses an external car battery) respectively. Both worked fine
although the on/off switch on one had lost its rubber "boot" which cost
about 50 pence to replace

John

"The3rd Earl Of Derby" wrote in message
...
MikeW wrote:
I need to put a small elec fence around the Veg patch this year
And I was thinking of making the energiser (using 12v Batt) myself but
have been unable to find a diy design/schematic.
Anyone done this or have a link to a suitable schematic.
TVM

No circuits, but plenty of electric fence energizers on ebay.

Yes at silly money. One has just gone for £62. plus carriage

MikeW wrote:

Dave Plowman (News), : wrote:
In article ,
Sponix wrote:
In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

Car ignition systems have short HT leads usually made of a resistive
material to cut down RFI. And the whole lot (usually) shielded by
grounded metalwork. Think the average fence might just act like an
aerial...



But with an elec fence there is no spark and hence no current flowing so
no RFI
Until something completes the circuit and gets Zapped.


I think


The fence will exhibit capacitance to earth and there will be a pulse of
current flowing in on the rising pulse, then discharging back through the
coil.

A small capacitance admittedly, but combined with a fast rising high voltage
pulse. It's bound to generate some RF, but how much I have no idea.

But it's unlikely to be any worse that any other electric fence gear based
on the same tesla coil principle.

The OP could test it crudely with an AM radio at various distances from the
fence - asking the question - "would I be ****ed off by this if I were a
neighbour?".

Hardly a scientific method I know, but if he's managed a peculiarly
efficient interference generator by some freak of physics, it should be
obvious


Cheers

Tim

Tim S wrote:
MikeW wrote:

Dave Plowman (News), : wrote:
In article ,
Sponix wrote:
In theory it won't cause any more interference than a car ignition
system as it uses the same parts.

Car ignition systems have short HT leads usually made of a resistive
material to cut down RFI. And the whole lot (usually) shielded by
grounded metalwork. Think the average fence might just act like an
aerial...



But with an elec fence there is no spark and hence no current flowing so
no RFI
Until something completes the circuit and gets Zapped.


I think


The fence will exhibit capacitance to earth and there will be a pulse of
current flowing in on the rising pulse, then discharging back through the
coil.

A small capacitance admittedly, but combined with a fast rising high voltage
pulse. It's bound to generate some RF, but how much I have no idea.

But it's unlikely to be any worse that any other electric fence gear based
on the same tesla coil principle.

The OP could test it crudely with an AM radio at various distances from the
fence - asking the question - "would I be ****ed off by this if I were a
neighbour?".

Hardly a scientific method I know, but if he's managed a peculiarly
efficient interference generator by some freak of physics, it should be
obvious

We have a moderately high powered electric fence energiser for our
fields - it's rated to energise 50km of fence if I remember right, I
expect I could look up the actual energy in Joules if anyone is really
interested. It does produce audible clicks on Radio 4 on long wave on
a radio which is actually within part of the fenced area. We are in
South Suffolk so the Radio 4 signal is adequate but not very strong.

--
Chris Green