HV Step Coil / Transformer for Electric Fence

Fly back transformer from an old TV...

I advise you to retract your posting, some people are cat egoric against scarring animals

Why, how many Engineers work in the Defense industry which I refuse to work in they kill people with their designs! So I give a small shock to a cat and I love cats but this one is causing damage to my property (screens & blinds) and scaring my cats. So should I tell everyone who develops smart missiles to retract their post?

Water is cheaper, more humane and just as effective a deterrent (more so in that it is easier to hit a cat with than chasing it around the yard with a homemade cattle prod).

For indoor deployment (firing out of a window or door way) I would suggest a "super soaker" toy water pistol or similar (much less mess than a garden hose). After its soaked a few times the cat should get the message. If it is hard to hit (some cats are), you could alternatively consider garden sprinklers so when it enters the yard it is almost guarenteed to get wet no matter which way it runs.

I have talked to the neighbor several times and she does not do anything about it

It's a cat, they are very independent and do what they want.

Alternatively get a dog.

Wait you do not know my water bill! Yes I know the cat is thinking he owns my yard and I never had a problem with the cat until over a year ago when it tore up (2) screens. I am very independent also and disabled also and do not need this stress. They do not call me maveric_manic for nothing. And I can not spray a cat with anything because it is long gone after the attack. Do you think the cat is going to sit around and wait for me to go outside turn on the water and spray?

Well if you want to go electric, and since no one has mentioned it (except you of course), the easiest and cheapest way IS to use an old car ignition coil. There are plenty of electric fence using car ignition coil designs on the internet and the ignition coil can be obtained fairly cheaply from a local wrecker yard.

Some example designs........

http://www3.telus.net/chemelec/Projects/Fencer/Fencer.htm

http://www.discovercircuits.com/P/pwr-hivolt2.htm

Plenty more designs on the internet (google "electric fence ignition coil" or similar), even cheap kits (electric fence and Jacobs ladder are suitable) if you don't want to build your own PCB (you just need to supply the ignition coil). If you want to build it from scratch the parts can be obtained very cheaply (even the ignition coil).

Yes you can use a TV HV transformer but it is more difficult and dangerous to build (and the design needs to be tailored to the transformer characteristics which varies from TV to TV), and I wouldn't recommend it unless you found a specific design on the internet and the specific TV transformer mentioned in the design.

Yes, you can use other transformers (like lighting), or step-up HV power supplies and designs, but you really need to know what you are doing and ensure you don't electrocute yourself during construction, testing and use. Plenty of these designs on the internet, google "HV power supply designs" or similar. From my experience, costs are going to be about the same (or more) as the car ignition coil design, however.

Very good answer and thanks for the links. I had planned on making a Jacobs' Ladder someday. That snake is too much I am going to save that picture. I thought about the junk yard but I do not have one close to me and those guys rip you off I have dealt with one. I may just make my own coil but I will check the net also. There are several HV apps I am interested in and making my own coils will help me understand magnetics more. As far as electrocution good point but I am much more afraid of 120VAC.

Just use a standard fence charger, available at your local farm and tractor supply. No serious damage to the critter. Some fiberglass poles and stand-offs gives a nasty but non destructive shock to any critter that touches a body part (usually the nose) to the wire. Iv'e been here 38 years and this is the best deterrant I have come up with.

I use rabbit wire and a single strand of electric fence at about a meter high around my garden. No problems. No cats, no racoons, no deer.

Alternately, the ballast from a flourescent light puts out about 16 kv.

The ballast is the 2 wire choke in a fluorescent light fixture? I have 2 or 3 of these. Yes I have seen the cattle HV device costs to much money I am an Engineer I build things my self in a custom fashion and I want to make sure it is safe with current limiting and shut off.

G'day gals, guys & gurus,

I used to have a pair of Doberman pincers that were primarily there to protect the property from unwanted intruders. That's if the dozy buggers ever got of their bean bags.

Anyway, I had a similar problem with the neighbours cat. Despite being in imminent danger of being torn into bite sized chunks by the dogs the moronic moggie insisting on sunning itself in our back yard.

I went down the line of the commercially available electric cattle fence, fibreglass poles, clips and nylon woven tape that had stainless thread woven into it. All up it cost a couple of hundred Australian dollars and it worked like treat. Not only did it stop unwanted cats from straying into danger but it stopped the dogs from jumping on the fences and recking them. It was so effective that we later used it to keep the dogs out of areas of the garden that were under repair and contain them in a safe area whenever we had a BBQ or outdoor party.

One thing I did notice was that once either of the dogs or any of the neighbours cats had gotten stung by this magic white tape they never tempted fait again and always gave it a very wide birth, even when it wasn't energized. So, once it has had the desired effect you can get by with just laying the unconnected white tape where you want said creature not to go.

Ok, you could build a similar device for at most half of the cost I paid for the commercial unit but you have to decide whether the time and hassle of sourcing the parts is worth the hundred or so dollars you will save. There is also the safety aspect to consider. If for example somebody with an implantable pacemaker or defibrillator gets hung up on your system and suffers sever injury you could be in serious trouble indeed. Whereas with the commercial unit it at least should have been tested to ensure it can't cause such damage and if it does hurt somebody it leaves the manufacturer rather than you in the deep and nasty stuff.

In conclusion, yes a good idea and it definitely works but personally I would go down the commercial rather than do it yourself path.

Of course you could always up the output of the green LASER to say 5 kW or so, however, I'm not too sure how the neighbour would react to toasted tabby?

Sorry Del and other cat people, my evil mind just couldn't resist!!!!

Regards, masu

OK. This one's better... land mines!

Land mines! OK I did not even think of that one and I can be pretty evil. I have this saying and it scares non technical people "Never **** with a Electronic Engineer". I have said this to people and one woman started crying, my neighbor with the cat, and then I quickly said OK I am sorry. I was angry and should not have said that. I have a problem with people sometimes one of my biggest faults. But now I try to work out problems with people just like working on a design with design bugs.

Have you asked your neighbor to get her cat neutered?

No I do not know if it is He or She but that could be the reason for the attacks on my cats. My neighbor is nice but she has this attitude the same as another neighbor that cats should just run loose outside even if they cause damage to my property and scare my cats and I have told both of them beware. I am very patient up to a point and have been so far. This particular cat is very aggressive. I have thought of several electronic countermeasures not just an electronic fens. And this thread has been very educational to me. Just talking with fellow brothers in Engineering really helps me out more than you know. And I really like you smart people from all over the world. Some of you are pretty funny and thanks to all of you for helping me with my problem.

But anyway based on everybody's input I have decided that I may try ultrasonics first to scare the cat away then the electric fence method. Ultrasonics does not hurt but causes dogs to bark. I have already tried it. The shock I have done to myself but only pulsed 100V shocks. Can hardly feel it need higher voltage.

If it's clawing your screens and spraying, it's a male. Call the SPCA and tell them you're having trouble with a stray male cat. They'll come out and set a trap. Chances are that your neighbor won't be able to get it back without it being neutered - EOP.

Well If I did that my neighbor and her 3 teenage daughters would execute me probably by firing squad. I do not want to mess with any of the women on my block. I want to be stealthy and if anyone says what is that thing in front of your window I will give them the standard reply it is an outdoor Digital thermometer. LOL They do not know what a resistor is gee! Some of my neighbors have seen my Lab and have nothing to say they look kind of scared or amazed. No I do not want to make waves and my screens are almost bullet proof now very tough material. I have seen that cat hang on a screen on all fours and it looked kind of surprised. I went out there to check for screen damage and nothing at all did not make one little mark.

OK, though I'd think twice about the night time urination thing...

"This just in... Local man caught exposing himself in front of mother and three daughters - film at 11:00"

LOL > Factorial 7. Listen you bouncing little Fuzz Ball you are cracking me up!!! First your land mines now this news flash! Maybe I should use you as my first experiment of a 10-20KV electric fence with no current limiting! Oh I just remembered I need to drink a lot of ice tea so I can let this cat know who is the boss. But I have to do it after 12:00pm because one of the daughters the oldest likes to be outside late with her boyfriend.

The ultrasound looks interesting.

Some time back I saw a couple of items on one of the Discovery Channels that you may find interesting.

The firs was a unit that generated a beam of sound that was around 300 mm in diameter. If your ears were inside this beam then you could hare the signal, however, if you were outside the beam even by as little as 40 to 50 mm you couldn't hear a thing.

From my understanding the system utilized a unit that could generate a confined ultrasonic beam with a frequency that was at leas 10 and possibly 100 times higher than a human can hear. The volume or amplitude of this ultrasonic carrier was then modulated with a standard audible audio signal. At the receiving end the ear and associated passages filter out the ultrasonic components in a way similar to the way a radio receiver removes the radio frequency carrier. This then leaves only the audio signal which the recipient can easily hear and understand.

The second was used to defend an ocean liner that while travelling down the African coast came under small arms and rocket propelled grenade attacks from pirates in small semi inflatable runabouts. Once the passengers and most of the crew were moved to the safety of the ship's core they wheeled out these octagonal search light looking pieces of kit. The moment these units were pointed at the attacking runabouts the pirates dropped to the floor like a sack full of jelly. Apparently it didn't do too much harm to the pirates but as soon as the beam was pointed away from them they beat a hurried and extremely rapid retreat.

There was no explanation given on how these devices worked but I believe they utilized an ultrasonic confined beam carrier to transfer a very low frequency signal that is roughly equivalent to being hit by a wall of water travelling at Mach I.

I haven't tried making either of these devices, but for your situation the first one is the way I would go. Not only would it scare off the offending moggie but would reduce the collateral effects on your friendly felines and the neighbourhood mutts. It would also be hard for the neighbours to twig on what's going on so there is little chance of them getting upset about it.

If you do try the ultrasonic beam I would really appreciate you posting your finding in this thread as I have several uses for such a device.

I am working on what I call the "A-Gun". It has piezo speakers up to 25kHz an oscillator, a high power bridged amp, and a Lead-Acid power supply and it will be mounted on a steel structure and look like a rifle. Totally self contained it will emit three types of frequencies, Audio 6-8KHz square wave, near ultrasonic about 15-16kHz or ultrasonic 22kHz. I have experimented with a low power version already. At 6kHz this device will blow you out of the house and I did it once with the A-Gun and my ears were ringing for about an hour. Near ultrasonic makes people and cats shake their heads it is like something is busing around in your ear not comfortable. Ultrasonic is for cats, dogs, mice, mosquitoes any animal/insect that can hear above 20KHz. I am told that the military uses such a device a deterrent. The thing about high frequency is that it is very directional and bounces off of hard walls and causes reverberation which sounds pretty cool. This is an experiment device but what I really mean an experiment weapon. When this thing is on people and animals flee. My neighbors are afraid what I am going to do with it but it is for experiments like you mentioned and for possums, cats, dogs that want to mess with me or get in my yard.

Vermin I which you would stop bouncing around you are making dizzy!

It is funny you mentioned Cardiac Pacemakers. I am a former designer of these devices St. Jude Medical Inc. and many people have misconceptions of these devices. The Pacemaker delivers more current to the heart than say a HV power supply and current is the key word. But you do have a point and I am looking for a sign that will say "Beware High Voltage". And a green laser of such power 50W gas laser, which I am thinking of building someday, would be enough. Check this site out mate: www.amazing1.com

I agree with you. I've used fence chargers and been accidentally zapped by them. It's remarkable painful but I never noticed any injury. I don't remember what we paid for our fence chargers, I don't think it was very much.

When we set it up I went back and forth on whether to run a ground wire or hope the rabbits grounded themselves well enough. I think I tried both (it's more than 20 years ago). Very effective. No animals crossed the line.

Oh just to add, a few years ago I did run an energized wire across a window area and I noticed a few days later that a houseplant that had made contact, had burned away at those points. Did not think that would happen. Interesting.

When the other cat "scares" your cats in your window does the cat get up on the window sill on the outside? I had a friend with this problem. He used "Tree Tanglefoot" on his window sill to get rid of the other cats. This product looks like clean axle grease. It is thick, waterproof and very sticky. It is made from vegetable oil and is non toxic. The neighbor's cat jumps up to the window sill, gets a "fur load" of Tanglefoot and spends several days trying to get the fur clean again. It does not harm the cat but it does give her a very bad memory of your window.

The company is at: http://www.tanglefoot.com/products/barrier.htm .

If interested, many hardware stores and garden supply stores carry it. Also a Google search and an Amazon search will turn up several sources.

No the two windows in question are mounted in stucco no window sill and I do not want to put that stuff directly on screens and/or window. I thought of just chicken wire around the windows but would look bad but a piece of chicken wire laying flat in front of the window on the ground electrically charged to give a small shock seems to be the best deterrent. The cat is a complete (you fill in the rest of the sentence).

Have you tried a cat-a-pult?

I would love to cat a pult that crazy cat but I told my neighbor I would not hurt the fuzzball. I am going to try ultrasonics also for those who thing I am mean. I have done preliminary test on my cats and they are scarred of the sound about 22KHz. This would be a deterrent which is better.

Human urine, sprinkled onto the ground near where the cat is known to enter/exit the premises, is a very effective, humane and inexpensive cat deterrent.

"Simples! ζ"

"Simples! ζ"

Did you want to say: SAMPLES??

Really, pissing on the ground in front of these two windows at night so no one sees me is a piece of cake. I will try it tonight thanks. I would rather piss on the cat but oh well. But it is not electronic! LOL

Yes it is inexpensive unless you have been drinking 12 year old Scotch and you have to keep peeing out there don't you? LOL factorial 7!

I am not going to sprinkle it I am going to soak the area!

i think i have your solution, for about $5.00 . if you go get a cheap disposable camera, disconnect the wires from the bulb and place some cat food around it... the results will probably give you first prize on americas funniest videos. The little capacitor that runs the flash bulb is several hundred volts, and hits like a tazer if you touch them together. if the camera is on, the system is charged, dont touch both wires or your the cat,lol.oh, yea, i guess i should mention it HOLDS a charge after you turn it off, too. you can run leads or wires off of them too, but i am not sure how much wire the charge will travel effectivly. the trick is to get the cat to touch both at once,or at least bump them together for a loud pop and bright arc flash. both wires laying under cat food close enough together for a tonge to lick them at the same time. This will be great, please video the results and send me a copy, heck, ill probably try it myself.

That is a good idea but one thing I do not like about it is if my neighbor sees a food bowl under my two windows she might think it is rat poison which is illegal. So I want stealth. But thanks for your input because you gave me an idea that is Disco Xenon Flashers. Discover Circuits has several and one runs off a 9 V battery and the schematic uses a 10KV transformer so take out the xenon light one lead to the chicken wire one lead to a steak in the ground and Mr. Fuss ball gets zapped. Just goes to show you it is not wise to cross an Electronic Engineer. Especially that wise guy that want to use land mines LOL. If you are going to be evil gadget mode you must be stealthy so you do not get caught.

well, you dont have to use the food bowl. i think the charge will travel through some distance with the wire,but again, both wires have to be touched at once. i dont think there is enough current to set up a ground contact, unless the ground is wet,anyway. I thought of this for you because when i was a kid, neighborhood dogs chased me on my bike. This was before cheap throwaway cameras, so i used an electronic flash from a 35mm camera, taped it to a broomhandle, ran wires down the handle to two needles. when the dog chased me again, i reached out and touched him. All four legs buckeled up and he rolled off into a ditch,and got up looking quite confused. My friends later wondered why the dogs didnt chase me anymore,just them,lol.

Lets look at static electricity. I had to attend a seminar for the FDA because I worked with Cardiac Pacemakers. They use CMOS chips. On a dry windy day just walk across the rug and your hole body is a capacitor that can hold a charge of several kV. You are grounded even wearing shoes and when you touch a metal object you discharge yourself and feel and sometimes see a small arc of electricity a single point contact with your finger plus earth ground your feet. This is the same principle not much current but high voltage. Though your method of touching two contacts is more efficient. So current can be very low like static electricity as long as you have HV in the kV range. Even a cat on a windy day touches the noise against metal I hear and see the cats reaction of getting shocked by HV charge stored in the cat and four feet grounded same thing just more feet which is a better ground. LOL The more feet the better!

I got a spark coil out of an automobile junk yard. Old spark coils aren't very marketable. I used a flashlight battery as a source and gave a friendly shock to squirrels that were eating all the bird feed, keeping the birds from the feeder. A shocked squirrel would just jump off and with feet running before it hit the ground, would run up a tree. I had to quit as my daughter said it was cruelty to squirrels.

Admitting to not reading ALL the replies here; where would you put the wire? I have a weed burning hog fence charger that I got from my father in law and installed it near the bottom of my wood fence about four inches off the ground to keep the dog from digging out. He only hit it one time and would never go near it again, even when it was turned off. The cat sat on it one time; one time. That was really something to see; never went near it again either. However, cats can climb fences even without claws. The one I have once killed a squirrel that came down the fence; I don't know how. It has also cooked snakes that have mistakenly tried to crawl over it.

If you don't want to hurt the cat.......stop shining the laser light into his eyes.

MuleHollow sells xformers

Most of the vehicles use step up transformer for ignition voltage. However, using such voltage to ward off pat animals may become a serious problem due to animal protection act enforced in your country. Be careful.

Perhaps use some ultrasonic noise generator that cat can hear on trespassing.

Laser is a bad idea.

I can understand your problem with that cat. I will give you some nice ideas, dont worry. Idea No.1. Catch the cat.Hold it firmely. Take a small hammer.Place the cat on a small table. Hit it on its head at 90* to the surface. While hitting be carefull not to hit hard. Then watch its behavier. repeat it for three days. If your problem is not solved give a final hit with a bigger hammer.

Idea 2.

Take a 2 A old transformer. Remove its core.Rewind it with this detail. Primary:10 turns with 18 SWG and secondary with 30SWG 2000turns. Connect a 12V AC to its primary. Make a small fence. Write a Notice DANGER with Red letters so boldly that cat should be in a position to read.

If your problem is still not solved , marry that cat owner girl.

Good luck.