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Nichrome wire rope cutter Answered

I've recently started working on a nichrome wire rope cutter. I've built a prototype that uses 2 9V batteries that connect in parallel to a 2" piece of 24 AWG nichrome wire. It works, but burns through the batteries within a minute of running them before they don't output enough current to heat up the wire. 
I would like to improve this by turning it into something that is much less likely to burn itself down, or electrocute me in the process. I've been looking into ac to dc converters so I don't burn (almost literately) through 9V batteries. I'm kind of a bit hung up on the electrical engineering portion of this however. If I were to use something like a 12V 5A power supply, and then nearly short it with the nichrome (a resistance of .2477 OHMs) is the adapter limited to 5A, or would something start to melt. I have a feeling I need another resistor in there to reduce the current (if I but a larger PS), and or a potentiometer to dial in the temperature. 
Any help would be appreciated.

Discussions

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steveastrouk

3 years ago

Just use a transformer, you don't need the expense of a power supply.

The PSU will trip out if you ask it to supply more than 5A, by the load you apply. You need a 1.5V supply to feed it with 5A.

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halolord01steveastrouk

Reply 3 years ago

Do you mean an ac to dc converter like this http://www.amazon.com/Volt-Power-Supply-Adapter-Standard/dp/B00B8TRF0A ? Because that is what I had in mind to use (or similar converter).

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halolord01steveastrouk

Reply 3 years ago

Hm alright, not sure how much I like plugging straight into a 120V AC source, but maybe it's the way to go.

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steveastroukhalolord01

Reply 3 years ago

The other side of the transformer is low voltage !! NOT, repeat NOT mains. Do not fasten anything directly to the mains.

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Toga_Dan

3 years ago

or you could use a drill battery.

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Downunder35mToga_Dan

Reply 3 years ago

Genius!!!
Not just the battery, take a dirt chep one and gut it.
Connect the wire instead of the motor and you can adjust the cutting current.
When done just plug in to recharge!
Should have thought of that fiy years ago :(
Too bad I am too low on time otherwise I would make a quick Ible out of it.

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Toga_DanDownunder35m

Reply 3 years ago

when drill Batts crap out, likely not all cells are crapped out! So, yay! Chop it up, the individual cells are close enough in size to C cells to fit a charger (make sure to use compatible charger, NiCad for NiCad, etc)

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Toga_DanToga_Dan

Reply 3 years ago

I could do an ible on that, but I gots otherstuf to do.

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halolord01Toga_Dan

Reply 3 years ago

That's what my original plan was, but I put it on the back burner when I accadently welded off the tip of my voltmeter trying to measure the current. But yeah, that's probably what I'll go with, although I might need a large wattage resistor, otherwise the wire will try to draw somewhere around 75 amps.