Ignition Coil Fence Charger

[Whfarms]

I have looked over the internet and found several schematics and have even built one. It would not not hold a mouse. I have attached an old post from @kellys_eye








I want to be able to eliminate the 555 timer and instead replace it with a arduino nano. I then can turn the fencer on and off over wifi and create a program that offers more sparks quickly then a delay. I am thinking Zap, Zap, Zap, Delay. Before I go any further does anyone have a usefull comment.

 

[Minder]

I built one last year as a deer deterrent around the veg garden using a waste spark automotive ignition coil.
Just the supply and a 8 pin Picmicro & Mosfet. produces two shots in quick succession every second.

 

[Whfarms]

So far I have used a typical 20K volt ingnitioon coil and attempted to design a PCB with a Mofset to open and close the - at several different durations. The spark is whimpy and isnt at all what I am after. Im looking for 20Joules or 10K volts. More importantly when I test the fence we want a min of 10k volts.

I have considered using a monster electronic hot coil. They come with a trigger pin, +12V, and a few ground pins. I could simply trigger the coil.

I'm not sure how familiar one is with electric fence but they all talk Joules. More the better.

 

[Minder]

I have not measured the value generated, but it can draw a arc over 1/4" !
The deer do not appreciate it also.
I just use single galvanized wire with one length buried in the soil for some length for ground.

 

[73's de Edd]

Sir whfarms . . . .

and have even built one. It would not not hold a mouse.
I wonder if that reason might have been that you used a new generation spark coil , and not one of the pictured older generation . . . .akin to this type . . as having either a 6 or 12V primary.
This " old school " type . . . . .



Not a new age Honda or Toyota "mini"







Additionally there is also a circuit design /concept/technique of the using of developed HV DC to charge up a 1 ufd poly cap to ~ 250 VDC and then to discharge that into the ignition coil primary via a 555, gate triggering a SCR.
I know for ABSOLUTE quadruple-triple DAMN sure . . . . . that will work ! and cause the incurred auto reflex shrinking of a bulls gonads up into the size of peanuts . . . . if being for, but just a few 100's of milliseconds.


Now, what say ye . . . . . .


73's de Edd . . . . .

A wasp stung an older gentleman on his private member.
He made an urgent visit to his doctor and explained the situation.
“Doc can you please just take away the hurt of the sting ?" he pleaded.
“But, PLEASE don’t do anything about the swelling?”

 

[Minder]

Sir whfarms . . . .

and have even built one. It would not not hold a mouse.
I wonder if that reason might have been that you used a new generation spark coil , and not one of the pictured older generation . . . .akin to this type . . as having either a 6 or 12V primary.
This " old school " type . . . . .

”

The modern automotive wasted spark version I used worked like a charm, the nice thing using a micro, you can tailor the spark sequence how you wish.
I just used one of the outputs for GND.
12v DC used to operate it.

 

[Bluejets]

The modern automotive wasted spark version I used worked like a charm,

Possibly....however there still remains that which #5 stated, there is a difference between old school kettering type coils and the newer cdi /cop style...entirely different.

One can buy a 4 wire 12V dc cdi "black box" and a GY6 (all cdi) system from China, add a small mod to get it to work with a hall effect, standard transistor, points or whatever for a little over $30 in most places.
Guarantee that will shift your mouse real quick.

Could have any uC mod added as well if you can eliminate noise problems that would definitely crop up.

 

[Whfarms]

Sir whfarms . . . .

and have even built one. It would not not hold a mouse.
I wonder if that reason might have been that you used a new generation spark coil , and not one of the pictured older generation . . . .akin to this type . . as having either a 6 or 12V primary.
This " old school " type . . . . .

View attachment 62464

Not a new age Honda or Toyota "mini"
View attachment 62466






Additionally there is also a circuit design /concept/technique of the using of developed HV DC to charge up a 1 ufd poly cap to ~ 250 VDC and then to discharge that into the ignition coil primary via a 555, gate triggering a SCR.
I know for ABSOLUTE quadruple-triple DAMN sure . . . . . that will work ! and cause the incurred auto reflex shrinking of a bulls gonads up into the size of peanuts . . . . if being for, but just a few 100's of milliseconds.


Now, what say ye . . . . . .


73's de Edd . . . . .

A wasp stung an older gentleman on his private member.
He made an urgent visit to his doctor and explained the situation.
“Doc can you please just take away the hurt of the sting ?" he pleaded.
“But, PLEASE don’t do anything about the swelling?”

I did indeed use the top coil. I will post the schematic later tonight.

 

[Minder]

Possibly....however there still remains that which #5 stated, there is a difference between old school kettering type coils and the newer cdi /cop style...entirely different.

Maybe a slight difference, but had success with both. !

 

[crutschow]

Im looking for 20Joules or 10K volts

A standard old-style ignition coil has an inductance of 8mH and a max current of 5A, so the spark energy is 1/2 LI² or 100mJ, far below the 20J you want.

For that you could use a capacitive discharge (CDI) system.
You would charge the capacitor to 100V for 10kV out.
The capacitor energy is 1/2 CV² so it would need to be a 4mF (4,000µF) capacitor for 20J..

Unless you have a very long fence, that seems to be way more energy than you need.
I would think 1 or 2 Joules would be sufficient for most fences.
A typical value is 1 Joule per mile of fence.

 

[Whfarms]

I have miles and miles of fence and it isn't always the cleanest fence. On top of that most are 4 strands so a 5 mile fence requires a 20J fencer. I do think that a person could increase the voltage and adjust the shock length (safely) and the rhythm to reduce the need for as big of a fencer. The joules makes the current go further but not "hotter" as I understand it.

(I must admit that I've studied, while scratching my head, the electric fence math on the internet and it seems like messing with the rhythm AS AN EXAMPLE: ZAP, Delay(4), Zap, Delay(4) Zap, Delay(4), Zap Delay(800) may prove to be the most effective at reducing the need for so many joules or volts. I like my fence to be 8kv minimum at all times.)

For conversation sakes I circled the area I was thinking of eliminating from the previous spec and driving it with an arduino uno.



I apologize I won't be able to post the schematic of the "mouse" fencer until I get into the office tomorrow. I cant get logged into the proper EASYEDA account.

I have used some pertronix ignition FlameThrower coils and electronic points in the past. A Excellent electric fencer can cost 1 to 3 thousand dollars. If I could come up with something that worked well it would save me a bunch of money.

 

[crutschow]

The joules makes the current go further but not "hotter" as I understand it.

The Joules (amount of spark energy) charges the fence capacitance which, of course, increases with distance.
If you don't have enough energy than the spark will be low voltage and weak.
Changing the shock length and rhythm will not significantly change the Joules needed for a given fence length and voltage.

(Why do you need four strands of wire for an electric fence?
How about just electrifying one strand and grounding the other three to minimize the Joule requirement?)

 

[Whfarms]

The Joules (amount of spark energy) charges the fence capacitance which, of course, increases with distance.
If you don't have enough energy than the spark will be low voltage and weak.
Changing the shock length and rhythm will not significantly change the Joules needed for a given fence length and voltage.

(Why do you need four strands of wire for an electric fence?
How about just electrifying one strand and grounding the other three to minimize the Joule requirement?)

Because animals are different heights. Most of the time we only use 2 or 3 strands but we run fences that are many miles long.

I agree that the rhythm doesn't change the Joules needed but a couple low intensity shocks may be enough to deter the animals from pressuring the fence. Im looking at the CDI things now. Some CDI systems are hundreds and some 20-30 dollars. Im not sure how to read the spec to determine the Joules.

 

[Whfarms]

As another example is there a way to tell from this picture the Joules:

For that you could use a capacitive discharge (CDI) system.
You would charge the capacitor to 100V for 10kV out.
The capacitor energy is 1/2 CV² so it would need to be a 4mF (4,000µF) capacitor for 20J..



Or should I build a circuit all from scratch and make my own CDI system?

 

[crutschow]

Im not sure how to read the spec to determine the Joules.

If it doesn't say, then you need to determine the value of the charge capacitor, and the voltage it is charged to.

As another example is there a way to tell from this picture the Joules:

No.

Or should I build a circuit all from scratch and make my own CDI system?

Likely the only way if you want 20J of spark energy.

What power do you have available to power the fencer circuit?

 

[Whfarms]

If it doesn't say, then you need to determine the value of the charge capacitor, and the voltage it is charged to.

No.

Likely the only way if you want 20J of spark energy.

What power do you have available to power the fencer circuit?

I would like to start with a battery if possible.

 

[crutschow]

I would like to start with a battery if possible.

Say you pulse one 20J pulse per second, that's 20W average power.
So a typical 50Ah, 12v car battery would last for (50A*12V) / 20 = 30 hours, not counting any inefficiencies.
You would need a 100-200W solar panel to keep the battery charged, depending on your location.

I have generated a relatively simple design for a 120Vac powered, 20J CDI, if interested in using line power.

 

[Whfarms]

Say you pulse one 20J pulse per second, that's 20W average power.
So a typical 50Ah, 12v car battery would last for (50A*12V) / 20 = 30 hours, not counting any inefficiencies.
You would need a 100-200W solar panel to keep the battery charged, depending on your location.

I have generated a relatively simple design for a 120Vac powered, 20J CDI, if interested in using line power.

Would you kindly share a schematic. Today 1/2 of my fencers are 120v. I was shooting for the moon.

 

[Bluejets]

Maybe a slight difference, but had success with both. !

Of that I have no doubt BUT hook a cdi coil up to 12v direct or via switching and you'll burn the crap out of it.

Have to remember the Op has trouble knowing which way is up (conservatively)

 

[crutschow]

Would you kindly share a schematic.

Ran into a problem.
My simulation shows high dissipation in the SCR trigger when I increase circuit values to handle a 20J pulse.
I'll think some more about that, but have no obvious solution presently.