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Rat-Zapper?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by HarveyH42, Apr 16, 2008.

  1. Torben

    Torben Well-Known Member

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    Whatever makes you happy. Myself, I'd far rather make inane comments to defend a stranger than to attack one.

    That's not the topic. The topic is building an effective rat zapper.

    Anyway, I'm done. If you want to continue your little rant you can PM me.


    Torben
     
  2. HarveyH42

    HarveyH42 Banned

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    No sign of a rat in about a week now, so guessing that problem is over. Sorry about causing all the cat-hate debate. The problem isn't really the cats, it's the owner, and his tendency to over-populate his property and the neighborhood. He thinks he's doing a kind thing, by feeding and housing any strays that show up, but it not good for the rest of us who live in the neighborhood.

    The zapper I put together, most likely wouldn't do any serious harm to the dog, or cats. Probably wasn't what killed the rat, but I'm sure it's unforgettable. Still going to work on a solar version, but need a lot of current, which I need figure out. Rather not buy solar cells just for this project though.
     
  3. HarveyH42

    HarveyH42 Banned

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    Dog found another rat this morning. Definitely not the same one. It's much bigger, and kind of torn up looking, missing some fur and dirty looking. Probably just older, hopefully not diseased. Set a spring trap out, but no luck. Didn't have time to set up the rat zapper. I want a more powerful one, so going to give a big can capacitor a try. Mostly, it'll be guessing, and using parts on hand. Any suggestions would be helpful before I plug it in...

    The capacitor is 37,000 uf at 95vdc. I have 15 of them, so adding more isn't a problem if needed. Thinking about using 2 huge diodes to rectify 110 VAC to DC, and drop it down to 70-80 vdc with some 5 or 10 watt resistors in series. I know I've got 5 watt, probably 10. Got a few really big 8 inch long ones (don't remember the values, low resistance though). Figure an Ne-2 lamp and resistor will work the same as on the smaller version and indicate when the capacitor is charged, and limit over charging. Won't leave it plugged in after it's charged up, should retain a nasty level for a day or two. Anyway, this is just a quick and dirty, to get something out there. This weekend, I plan on mounting some stainless steel plate inside some 4" PVC, two on each end. Drill some large holes near the middle to bait it, and add a break-beam circuit there as well. When the rat is well past the plates (point of no return) and breaks the beam, a relay trips, energizing the plates withe the charged capacitor. Since the plates should be unloaded, the contacts of the relay shouldn't be abused when the rat completes the circuit. Only problem is that the rat may not be interested in food, as it's plentiful over at the cat-man's property, water too. Guessing they are coming over here for a quiet/safe shelter. Have to change that.

    Will post some pictures soon. Need to do some math, but really don't know much about this level of power, kind of avoided it all my life. Hope one 37,000 uf capacitor is enough. Maybe I should plan on two, just to make sure. Damn, almost forgot a safe/sane means of discharging the thing. The little zapper is 320 uf @ 300 vdc, and blows a hole in the bottom of a beer can, guess the big one will shred it...
     
  4. dave

    Dave New Member

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  5. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Be careful with that capacitor, just one capacitor charged to 95V contains 167 Joules. Defibrillators on a low setting are only 60 Joules. The 320uF cap at 300V only holds 14 Joules.

    Mike.
     
  6. HarveyH42

    HarveyH42 Banned

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    Now that's some scary news. Guess I should point the end of the PVC pipe over the fence to my neighbors yard, just in case the rat is expelled...

    While at work, I came up with a reasonably safe method to discharge the capacitor. Thinking I can mount a pair of ball casters in the bottom of 2 foot section of PVC pipe. I'll have a beer can held in place near the top with a pull pin on some fishing line (only thing I could think of that couldn't possibly conduct electricity). Probably look pretty cool at night time.

    How did you calculate the joules? I was figuring on just enough voltage to light a neon bulb. I think it's around 60-70 volts. I haven't a clue on power and current. The diodes and resistors I'm planning on using, are from an industrial piece of equipment (same printers I got the capacitors), and should work. Just want to get as many details as I can, my first really dangerous project. Really hate this stuff. My tesla coil is safe, except the neon sign transformer. I know what I'm planning is bad stuff, and hope to take excessive precautions.

    Anyway, the rat was back this morning, and did some damage. It was in my utility room, and hopefully consumed enough poison. I had to packs in there, one is missing, the other was chewed open. The rat chewed a hole through some wood, and also destroyed a hose on my washer machine (water everywhere). Just got the hose replaced, jacketed with metal braid, so shouldn't happen again. Replaced the thin plywood with 3/4 inch. Need to paint it still. Thinking about putting some sheet metal over the outer surface, but don't think that rat has more then a day or two left...
     
  7. Boncuk

    Boncuk New Member

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    Hi Harvey,

    I thought the problem is solved already, which obviously isn't the case.

    Here is a method used by German farmers: They catch a rat alive, pour gasoline all over the body and touch it of releasing the rat for funeral. It will scream badly but it has the effect that all other rats in the vicinity will hear that terrifying screaming and as a result they will avoid getting close to your home.

    Of course there is some risk burried in the method. Farmers who forgot to close their barns didn't have to take care to tear them down anymore.

    In your case it might be helpful though if the cat turns towards the cat-fan's home. :D

    Hans
     
  8. HarveyH42

    HarveyH42 Banned

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    I started getting parts together, but could really get into throwing it together. Figured it would be better to get some sleep first. Took some pictures of some of the stuff. Couldn't find the box of high watt resistors I was looking for. Those really big ones aren't of much use (10:eek:hm: and 100:eek:hm: ), none of the others are more then 10 watts, and under 1K.

    Also posted a picture of the ratcam. Search a little, and a 8 mm wide angle lens seems to go for about $20. Think I'll stick with my $6 lens for now, and see if I can find a better deal later.
     

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  9. Hero999

    Hero999 Banned

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    60V to 70V is really too low to electrocute a human (I don't know about a rat) unless the skin is really moist so I wouldn't worry about it. A friend of mine touched the output terminals of a high powred LED constant current power supply; he barely felt a tingle and it's open circuit voltage was 75VDC.

    I would use a much higher voltage and use low frequency AC rather than DC as it's more effective (somone earlier in this thread said it's the other way round which is nonsense). The 120V AC line would stand a much higher risk of killing a rat than your capacitor, can't you use two light bulbs for current limiting an wire it hot to hot for 240VAC?

    If you really want DC then build a diode voltage multiplier from photo capacitors and diodes and connect it to the mains. Idealy the voltage needs to be above 1kV which should be able to penetrate the rat's fur.

    Are stun guns legal where you live? They're bound to be pretty lethal to rats, so what about ripping the guts out of one and using them to zap the rat?

    Are you sure your dog didn't kill the rat he found?

    I don't know why you've got such a rat problem where there are so many cats. I would have thought they would help to control the rat population. I've got tow cats and they always seem to be killing mice but I haven't seen any rats which is good.

    Also why are you bothered about rats outside? How are they bothering you? I say if they're not causing you any trouble then they aren't worth worrying about.
     
  10. HarveyH42

    HarveyH42 Banned

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    The rat I'm working on now did make it into the house last Thursday night, chewed through some plywood. He chew a hole in my washer machine hose, which sprayed mostly outside (fortunately). Could have been a huge disaster, as it was my utility room, water heater, breaker box (cover removed...).

    I've got something high voltage already wired up. Found it last week, don't even remember it. Think its an igniter from and old gas furnace or something. Must have been from when I first bought this house (15 years ago). Got about a 1" arc, not real hot white, but active.

    The neighbor over feeds everything. Got a hunch this rat has already eaten, before stopping over here, so a baited trap isn't likely to work. Have two outside, nothing in a week, two rat sightings.
     
  11. HarveyH42

    HarveyH42 Banned

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    Finally got some still from the rat-cam to post. Not the best quality, but not directly from the camera. Using a 6" LCD monitor next to my computer, nice picture. Used a Kodak digital to record (640x480), so loose a lot of detail. Ratcam.jpg is a screen capture from Quicktime player on the computer, not much difference in the quality over the framegrabber built into the camera.

    This is a different rat from Thursday's, and slightly smaller. Looks cleaner, healthier, little chubby (pregnant?). ***** took the bait I put on the rat-zapper, just some whole wheat bread I made last weekend. Was getting to throw it out, but will bait the spring traps with it tomorrow if it likes it so much. Have to wrap it in something conductive and hang it over the rat zapper's ground plate. Make sure it can't avoid closing the circuit this time.
     

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  12. Hero999

    Hero999 Banned

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    Good, I hope you get the little sod this time.

    The fact that your neighbour feeds the cats so much, shouldn't stop them hunting. It's a well known fact that starving a cat doesn't make it a better hunter, it'll only make it run away and go wild. By feeding the cats he's actually encouraging more of them to come and kill the rats. The problem is that there are probably so many rats in your area that the cats can't possibly control the population effectively.
     
  13. HarveyH42

    HarveyH42 Banned

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    I've never seen his cats hunting anything in over six years. I had a Siamese before he moved in. She hunted all the time, pretty much anything that moved, regardless of size. She was better at chasing off cats, then my last dog ( Rottweiler mix ). Those cat's next door are fat and lazy.

    Anyway, tonight will be high voltage night for the rat. Figuring on a 2 foot square of sheet metal for a ground plate, and a smaller platform about 4" above it with the bait, maybe a hard drive disk. Tough part will be a weather proof enclosure for the electronics. Don't expect rain anytime soon, but never know around here, and I'll need to leave it plugged in.
     
  14. HarveyH42

    HarveyH42 Banned

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    Finally got it finish, except a cover (oh well). Not great output, about a 1/4 inch. Used an old spark plug wire, as I wasn't finding anything else with thick insulation. Guessing they are resistive carbon fiber. Should still do well enough, or can replace it later. Went with a smaller ground plate (already cut vs. cutting into a much larger piece...). Instead of the hard drive disk (set it down, disappeared...), I used half a tin can with holes punch around the bottom. Rat should need to stand on the platform to access the bait. Only chore left is to move the Ratcam, but probably won't be up to watch (work tomorrow). Might get to catch some as I get ready for work at 1 AM.
     

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  15. Hero999

    Hero999 Banned

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    Trash pick an old CTR and use the HT wire which is copper cored and won't have such a great loss. How much does the cable heat up? Does it overheat when the arc is drawn for long periods?
     
  16. HarveyH42

    HarveyH42 Banned

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    Didn't notice any heat, but didn't run it very long. Just enough to check the arc. Wasn't about to touch anything that might bite. Pretty sure the wire will work, as this is sort what it was design for. Don't think the transformer's output is as high as a car's. More concerned about whether the transformer can handle continuous use, or if it intermittent. All free parts, so no big loss if it smokes and burns. Unlikely to start the house on fire, all metal and concrete in that area.
     
  17. mneary

    mneary New Member

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    This project has taken a life of its own. Is it still about the rat?

    A long time ago, live trapping was suggested. I recall the problem is that you didn't want to release it anywhere and make the rat somebody else's problem.

    Could you reconsider a live trap, and then find a way to errrr, ummmm, euthanize it/them? I fully understand how much easier it is to off him when you're not there, but the risks of unintentional injury or failure to dissuade him are growing.
     
  18. Hero999

    Hero999 Banned

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    We used a live trap for mice in the shed and released them near the brook at the end of our street. I don't care if they find their way back to our garden. They shouldn't go back to the shed as it's vermin proof - someone just left the door open one night. Mice generally don't do much harm in the garden, they're both good and bad as far as I'm concerned, they might eat the odd strawberry but they also eat other pests like slugs and grubs.

    Rats on the other hand are a general pest and not something you really want anywhere. The question is, if you use a live trap to catch the rat, what do you do when you've caught it? I can think of also sorts of ways of killing rats (some more humane than others) but the cleanest one I can think of is to gas it with CO2. Just put the rat and trap in a large plastic bag and fill it with CO2 (you can get CO2 canisters fairly cheeply). The rat should loose consciences within a miniute and die within five miniutes.

    I've seen this been done with chicks on TV and it seems pretty painless enough. Lol I've inhalled the residual CO2 left behind in a cream soda bottle and it made me light headed so I think I know what dying from CO2 poisoning - that the rat will just feel really light headed and faint.
     
  19. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Just chop off the head of the rat with a guillotine. Then it will feel light-headed. It and you might faint.
     
  20. HarveyH42

    HarveyH42 Banned

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    Haven't seen any sign of rats in two days now. No new dead rats either, been taking the dog around the entire property, and around the block. He seems to find them pretty easy. The nights I've seen the rats, the dog is usually all over the fence. Last night he ran out, looked around some, peed on the orange tree, went back in the house. Kind of thinking they were looking for water, which I removed from the yard.

    Going to leave the rat-zapper plugged in for a while. It's been 3 days continuous, and doesn't seem to mind.
     
  21. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I'm not into rat psych, but CO2 gassing is probably not very humane from the rat's point of view, based on human response to it. CO2 causes a sense of suffocation, struggle, and anxiety. CO is probably much more humane, as is rapid decapitation. Rats may have a pretty strong startle/freeze reflex, like mice, so even releasing them to a predator is probably not perceived by them as too painful. John
     

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