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Need help building a shock circuit...





quex
Hello, all! I'm looking to build a rudimentary shock device to get squirrels and raccoons off the birdfeeder. The internet has thus far not yielded a good set of instructions, though, and being at least four years out of my most recent physics class, I need some help from you geniuses. (Pretty please!)

My plan is, simply, to run two coated wires from the metal casing of the house through a nearby window, with a battery connected to one wire and the other ready to close the circuit when there are only squirrels (or that damn raccoon) on the feeder. Very simple, but for the trouble of what battery or matrix of batteries to use. I don't want to kill anything, just teach it a good lesson -- our current method of deterrence is a 6mm plastic pellet gun, which barely bothers the squirrels anymore, and the raccoon apparently can't even feel.

So, can anyone roughly guess the voltage/current needed to give a small animal a painful shock, but NOT kill it? Also, any specific instructions about ramping up the voltage of a 9v (or other) battery to reach this threshold would be greatly appreciated.

(In the meantime, I'll be outside with the pellet gun.)
Bikerman
You will need a transformer to step-up the voltage. You need a high voltage and a low current. I'm not sure what sort of voltage is used in the commercial products - I would guess a few thousand volts (probably 3000-5000V should do it) at very low current.
Commercial electric fences also use a pulse generator to switch the system on and off (once a second or so I seem to remember).
You are going to need something like a car battery to power it (for any reasonable amount of time).
quex
I know there's a way to do it with a 9v and relatively little hardware, because the three models I've tried to dissect with my eyes at the home improvement store accomplish the task in a small space and use a 9v to last "3-4 months," according to the packaging. Nevertheless, that was good info -- thanks! Low current is good to know, but 3000-5000v sounds a little high... then again, I suppose it's in the same range as a carpet shock. A transformer, eh? And they'd have those... not at the hobby shop...? -_-;;;

I think I'm gonna be stuck with this pellet gun a while longer.
Bikerman
quex wrote:
I know there's a way to do it with a 9v and relatively little hardware, because the three models I've tried to dissect with my eyes at the home improvement store accomplish the task in a small space and use a 9v to last "3-4 months," according to the packaging. Nevertheless, that was good info -- thanks! Low current is good to know, but 3000-5000v sounds a little high... then again, I suppose it's in the same range as a carpet shock. A transformer, eh? And they'd have those... not at the hobby shop...? -_-;;;

I think I'm gonna be stuck with this pellet gun a while longer.

Well any electronics shop should be able to help - Radioshack for example. You will probably find that they will also be able to advise on a pulse/interrupt circuit. You may be able to power it with a small 9v battery - it depends on the length of the run and the number of 'shocks' given. The high voltage should not be a concern - it is painful rather than dangerous Have you ever got a belt from a spark-plug? Hurts like hell, but won't kill you. In that case the voltage is upwards of 20,000V. This is what you are aiming for on a smaller scale...
ocalhoun
Would it be possible to run it off of AC power? If I were building it, I would want to do that in order to avoid messing with replacing batteries. Heck, it might be possible to use straight wall current in it, if you don't mind picking up fried squirrels out of your yard. Just put a circuit breaker in it so that it won't blow your house's breakers when it goes off.

Wall power plug|=====(breaker)=====<Squirrel
That certainly would be a simple way to build it!
Bikerman
ocalhoun wrote:
Would it be possible to run it off of AC power? If I were building it, I would want to do that in order to avoid messing with replacing batteries. Heck, it might be possible to use straight wall current in it, if you don't mind picking up fried squirrels out of your yard. Just put a circuit breaker in it so that it won't blow your house's breakers when it goes off.

Wall power plug|=====(breaker)=====<Squirrel
That certainly would be a simple way to build it!

It would but I wouldn't be happy advising it. A battery will never deliver a fatal shock (unless you go nuts and start stacking car batteries). Mains AC can easily do so...
quex
ocalhoun wrote:
Would it be possible to run it off of AC power? If I were building it, I would want to do that in order to avoid messing with replacing batteries. Heck, it might be possible to use straight wall current in it, if you don't mind picking up fried squirrels out of your yard. Just put a circuit breaker in it so that it won't blow your house's breakers when it goes off.

Wall power plug|=====(breaker)=====<Squirrel
That certainly would be a simple way to build it!


...I'd be worried about the EMS picking up a fried me off my yard. That said, I may very well try this for the raccoon if he withstands the battery version... I hate that little bastard!! XD
(Thanks!)
Bikerman
I managed to dig out a circuit diagram and brief build description for an electric fence from a back edition of Circuit Cellar.
It's in pdf format. Anyone who can read a basic circuit diagram should be able to knock this up for you...
http://bikerman.info/resources/electricfence.pdf

(Page 80 onwards).
Arnie
It should be noted that the amps say much more about the lethality of a shock than the volts.

Other than that, I can't help but ROFL at this thread and wish you good luck chasing the #%&^@ raccoon off your birdfeeder. Laughing
jwellsy
I'm thinking an electronic fly swatter powered by an old solar light.





http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40122
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768

That would be $20 or less in parts.
chatrack
Quote:
I'm thinking an electronic fly swatter powered by an old solar light.


Hi,

There is electronic fly swatter is an oscillator with power transistor. It uses a step up transformer as inductance.

The secondary voltage will be high and less current capacity(means less heat produced up on current flow). Now feed the secondary out to two lines.

I have one sugession that this circuit can be swithed ON
with a "touch activating circuit" with a "delay" circuit, which is connected to the same two line.

In that case a electo magnetic relay will be needed for switching.
ocalhoun
jwellsy wrote:
I'm thinking an electronic fly swatter powered by an old solar light.

Could the solar panel really provide enough energy for that?
Helios
Arnie wrote:
It should be noted that the amps say much more about the lethality of a shock than the volts.

Other than that, I can't help but ROFL at this thread and wish you good luck chasing the #%&^@ raccoon off your birdfeeder. Laughing


I'd use watts for the best accuracy.


Now, about the shocker. Well, of course it's possible to design a rather complicated digital circuit with certain types of ignition, maybe even based on AC (controlled with a thyristor for example), but I'd rather stick to the most simple solution you can find (maybe even mechanical?), because even a small and 'easy' circuit can be a headache (or even dangerous!) for the inexperienced.

Buying a ready device would be the best choice. Sure, it will cost more and, maybe, it's hard to find, but these are its only disadvantage.

If you insist on building an electronic circuit, I'll try to find something online (which has been tested!).
Hmm... maybe something based on this: http://www.aaroncake.net/circuits/hvgen.asp ?
Edit: another link: http://www.freepatentsonline.com/3900770.pdf <-- you probably need to be registered (free) on that site to view.
coolclay
I don't think the solar panel could provide enough voltage to power it if you connect it straight to the swatter, but if you attached it to a set of rechargeable batteries, as a battery bank of sorts, that would work great.

I built a solar powered radio from an old 12 volt panel I had around. I attached the solar panel to some old cell phone batteries I had partially disassembled. After a day of sun the batteries will power the radio for about an entire day. It's probably not a healthy cycle for the batteries because I have no charge controller but I've got plenty of old cell batteries, and it's worked great for an entire year now of almost daily use.
jickson
Get electric mosquito bat circuit, increase the step to deliver higher rate of voltage which can divert them...
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