Speaking to @Blank_Stare My design goal is to keep the current draw low enough to allow a simple solar charger to keep a SLA (sealed lead acdt battery topped off(more on this later)witt both the charger and the FC connected to the battery at the same time.

My current equipment configuration is set up exactly that way - the solar charger is always connected to the battery, which is a rechargeable 6 volt lantern battery.

It has been my intention to simply tie into the same alligator clips that power the equipment, not only for simplicity, but to conserve as much space as possible.

I think the hardest part of this project has been the space considerations - a deck of playing cards isn't much to move around in.

Thank You

 

But shocks from ignition coils are generally not considered life threatening because of the low current (although they hurt like heck ). It's the current that kills.

I've been bitten while working under the hoods of old cars (well, they weren't so old at the time...) I would say that you are understating how much it hurts. It's enough to make a grown man cry. The plug cables were old and cracking, and I thought the devil had me by the elbow.

I stopped working on cars in the rain after that. I was slow to learn the lesson, but I learnt it good.

 

Yes, car ignition transformers were worth about 20KV 55 years ago.
No, it wasn't mild. The only thing that saved me from wet pants was that when I get shocked, everything clenches shut.

Fence chargers are vaguely similar to CDI - 40kV isn't all that unlikely.

 

We fixed several different types of fence chargers years ago when I went to school. One came in that had an automotive type flasher in it as part of its circuitry. The student working on it went to the auto shop, borrowed a flasher, plugged it in and that cured it.
Our test device consisted of a long hair we named "Hippie". He could grab the terminals of a charger and rate it's capacity. Nobody ever questioned his ratings

 

We fixed several different types of fence chargers years ago when I went to school. One came in that had an automotive type flasher in it as part of its circuitry. The student working on it went to the auto shop, borrowed a flasher, plugged it in and that cured it.
Our test device consisted of a long hair we named "Hippie". He could grab the terminals of a charger and rate it's capacity. Nobody ever questioned his ratings

As a kid I used one of my little sisters to check if a single cylinder engine had 'juice'. Till my mom caught me.

 

I'm using a Parmak fence charger (6v battery with solar panel) for the horses. It says 'Low Impedance' on the front. What does that mean? Also, a fence charger's effectiveness depends a lot on how you ground it.

 

It says 'Low Impedance' on the front. What does that mean?

I would guess that it means it can still operate with a high impedance short, such as a plant leaf touching the wire.

 

I'm using a Parmak fence charger (6v battery with solar panel) for the horses. It says 'Low Impedance' on the front. What does that mean? Also, a fence charger's effectiveness depends a lot on how you ground it.

I have no what cluewhat low impedance means maybe othe models put a resistor inline to reduce the shockto make it less painful. If your fence uses metal fenceposts like most of ours did t iwoulbe a good ground, A metal leash hitch screwed into the earth used for dogs would be adequate, also if yo have a home the uses metal plumbing I used that for ground on my various radio projects. A spike(such as a really large nail) driven into soft soil would probably work OK. I made a far share and never sweated how I grounded them. Since many of them were also on barbed wire fences I use that fence for ground.

 

I used a 7 foot, galvanized ground rod driven 6 feet into the earth and a UL ground clamp with solid copper wire (awg 10) to ground post on the charger. Anything less and the critters won't respect it.

 

Version Mark one...

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Q1 needs to be a power transistor due to the high current surges, Q2 is not critical ( my goto NPN is a 2N2222 or PN22222aneither is critical, If anything gets hot there is something wrong . I have some trepidation about this design. It is untested and brute simple.

I like lead acid batteries because , in my experience is they just work better. This translates into bigger pulse that is more effective its supply volltage is also not critical though 12 v works better for obvious reasons.

 

Wendy, what is the transformer?

You cannot have diode CR2 as that will short the primary voltage pulse when the transistor turns off, giving no output high voltage on the secondary.
If you want to protect the transistor, you need to use a high voltage zener to ground instead.

 

I discussed this in post #11. It is a 120vac : 6,3 CT type, The ignition coil would also substitute. Keep the pulse narrow it will be safe. I choose the period for 60Hz because it should be be well within the range. of the transformer.Like the transistors I can be substituted by a wide range of parts. The fuse is a nod to the time honored traditionof the transistors protecting the fuse by blowing first.

I will draw a cmos 555 version. This is a simpler version but I will trust the 7555 version more to work the first time.

@crutschow Thanks for the comment: I have updated ehe schematic.

 

Here it is again Mark 1.2?


Got R2 wrong.

 

I meant you cannot have diode CR1, as it suppresses the spark.

 

It protects Q1, From the flyback emf from the transformer, same as I might use on a relay. The flyback emf has no use in this circuitbut might damage Q1. the pulse is cause by Q1 turning on and sending 12 VDC through the secondary coil (now the primary)of the transformer.. Actually there is no spark, just a narrow pulse 180ms at 120-220v on the high voltage side if the transformer. The lack of a damping diode is probably what killed my 1st project 50 years age, I've learned a lot since then.Still don't trust the astable oscillator very much. Someday god willing I can test it myself It would be easy to protoboard.A 555 is much more predictable.I have designed circuits that send 60hz AC thought the low voltage side at 60hz for 1 sec. but I now feel such an arrangement is not safe.I t is the120vac that bothers me.

 

My misunderstanding.
I thought it was a flyback circuit, like a Kittering ignition.

 

Here's some recommended electric fence voltages for animals.
It goes from 700V for pets to 5000V for long haired animals, so I don't think a few hundred volts is sufficient.

 

It was enough to knock cow down.good enough. never saw a cow sit like a dog before orsince.

 

It was enough to knock cow down.good enough.

Perhaps because she touched the wire with her nose.

The high voltages are needed to shock the animals through their thick hair.

 

This is a commercial electric fence which runs on 9V dc & draws minimal current. It uses a small HV inverter which generates 225V DC which built up in a capacitor & then dumped across another Transformer to feed the fence. The pulses are aprox 3 seconds apart, its a crude CDI type system & produces quite a reasonable spark.