Microwave oven transformer with or without ballast ... or neon sign transformer?

[owkaye]

Hello all,

We live on a small farm. During this past year I setup surveillance cameras around our property to observe nocturnal wildlife and keep an eye on our livestock from inside the house. One thing I learned during this exercise is that the rat population here is extreme, so I need to reduce their numbers dramatically.

My goal is to setup an electrocution trap in front of one of our cameras. When I see a rat or two crawl into the "kill zone" I will press a momentary switch that turns the power on for a second or two -- just long enough to kill them. The dead rats will then become "barbecue dinner" for raccoons, opossums, skunks, foxes, owls, and other wildlife that I actually enjoy watching at night.

I have a used microwave oven transformer to power this trap, and although I will never switch it "on" for more than a couple seconds at a time this still brings up a question:

Should I ballast it to keep the circuit breaker from tripping, or to prevent the MOT from burning out? I have two old 500 watt halogen lights I never use any more, and I could use one or both of them as my ballast ... but will this detrimentally affect the MOT's power output and rat killing ability? Or do you think the MOT will still put out enough power to kill rats when ballasted by one or both of these lights?

Or should I just skip the MOT/ballast and instead buy a cheap 3kV neon sign transformer on eBay? This option would cost more, but from what I have read NST's can be powered on forever without needing an external ballast, without burning out, and without tripping the circuit breaker. Is this true?

Are there any other advantages to using one power source over the other?

 

[RayRay1132]

You could try to ballast it, but essentially those lamps are giant resistors and they would limit the power output. It also depends on how many watts your MOT is. A neon sign transformer may or may not do the job, it also depends on how much amperage it can put out.

 

[owkaye]

Since ballasting the MOT will limits its power output, what do you think of this idea:

Install the MOT on a 30 amp circuit. This will probably have enough capacity to NOT pop the breaker when I switch the power on for a second or two. Then I do not have to ballast the circuit and I will get full power.

I don't know what my MOT wattage is. I've read that most of them are no larger than 2200 watts so I'm assuming mine is this much or less.

 

[RayRay1132]

It should, make sure that there are no shorts. Also, how often does the breaker trip, is it everytime you press the button, etc.

 

[owkaye]

How often does the breaker trip, is it every time you press the button, etc.

I have not yet tested the MOT in this application. I'm still collecting information so I can do this project correctly the first time. Others who have installed similar 'rat zapper' systems on 20 amp circuits claim that their breakers trip either frequently or every time. However, they may be leaving the power on for longer than 1-2 seconds.

If I use a 30 amp circuit I do not think the breaker will trip, but my other concern is possible damage to the unballasted MOT. I saw a youtube video where some guy turned the power on to his unballasted MOT and watched as it basically cooked itself. Smoke started pouring out of the thing, then it died. This took a minute or two from what I recall.

I do not think that turning on the power to an unballasted MOT for only a couple seconds would generate enough heat fast enough to damage it, especially if were allowed to cool down for 10 minutes or more before doing it again ... but I have not tested this either, so I'm just going on my gut feeling here -- which means I could be completely wrong about this.