Foam cutter power supply - RC Groups
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Nov 17, 2001, 05:39 PM
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ronnath's Avatar

Foam cutter power supply

Does anyone out there see a problem with using a car battery charger for a hot wire power supply?

I have a charger that is switchable with 2, 10, 12, and 50 amp outputs.

Yardbird sent me a photo of his rig that uses a 12 volt RS transformer, but since I have the car charger laying around I was thinking of using it.
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Nov 17, 2001, 07:01 PM
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schoey's Avatar
That should be fine lots of people are using car chargers, its just tricky getting the right combination, everyone ends up using something a bit different to get it working, good luck
Nov 17, 2001, 07:04 PM
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tenover's Avatar
I use a Zagi battery plugged into a 15amp Speed Control, then plug that into an extra reciever I have lying around. Then you just use your throttle control to adjust the heat. Works great, easy to "build", and you can use parts you already have....If you're just doing it for fun, you can't beat this method
Nov 17, 2001, 09:22 PM
Registered User
Hi Fellows:

In regard to cutting foam you refer to the bow cutter.

Is this simply similar to an actual insulated bow of some type with the cutting wire replacing normal string on a bow.Eg the output of the variable power supply directed to the resistant steel wire.

Any comments will be appreciated.

Nov 18, 2001, 01:39 AM
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buckeyes1997's Avatar

exactly what i use

i use a homemade bow with a battery charger setup.
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Last edited by buckeyes1997; Nov 18, 2001 at 01:44 AM.
Nov 19, 2001, 12:50 AM
Registered User

Foam cutter stuff

Hi Ronnath,

If the battery charger you have is not an electronicly regulated one you can adjust the output very easily by making a variable AC voltage source by using a good lamp dimmer. I made one by purchasing a 6ft 3 wire extention cord and a 2x4 (single position) electrical box with a wire clamp in one end. With nothing plugged in, I cut the outer jacket of the extention cord at a point about 1 ft. from the outlet end. I then looped the cord in and out of the same hole in one end of the electric box. To hook up the dimmer (they usually have two wires hanging out of them) just cut the black wire and attach them to the wires from the dimmer. One black wire to each side of the dimmer. For saftey strip a little of the green wire insulation and attach it to the metal part of the box. This is a saftey ground. You can use wire nuts to make the connections or solder and tape them (well). Put the dimmer in the top of the box and a cover and you are all set.

This will work with 'dumb' battery chargers but not too well with charger with regulators, or automatic chargers. I used a 3 amp transformer which converted 110v AC to 12.5v AC. I beleive you can purchase one of these at Radio Shack.

If you are buying a dimmer and want to make life a little easier, get one which has a separate off-on switch as well as the dimmer knob. That way when you get the 'heat' just right you can just turn it off and on without changing the dimmer setting.

Good luck Art

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