# Basic DC electronics question



## Revenant (Mar 17, 2007)

I experimented with my battery charger and dimmer box in my quest to build a hot-wire "table saw" and the results were quite good. So the large cutting-out scene is pretty well squared away. Now I want to make some small handheld cutters, especially a fine detailing tool for cutting out "engraving" and lettering.

The problem: This little hot-wire exacto would only use about 2" of element wire at the most, or less. That's not much resistance, and I'd rather not have to crank the power way up just to get the business end hot enough, so logically I figured I'd just add a resistor or two on my circuit.

*THE QUESTION:* Does it matter if I add the resistor at the positive or negative pole? My limited knowledge of electricity leads me to understand a resistor as "bottleneck" to the current. In a fluid, that would cause a pressure difference before and after. So if I want to increase the resistance of my little wire element, do I put the extra resistor "upstream" or "downstream" ? Would that be on the positive or negative side of it? Does it matter?


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## krypt (Oct 25, 2005)

Im pretty sure it does'nt matter, but wish somone would verify it though.


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## Otaku (Dec 3, 2004)

Resistors don't care where they are. The total ohms will be a combination of the resistor value and the wire (when wired in series). Remember that the resistor can get hot, too. If you get a hot resistor and still can't do the cutting, try a lower value resistor.


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## Revenant (Mar 17, 2007)

Sounds like I got my answer! Thanks much!


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## DeathTouch (Sep 6, 2005)

It doesn't matter, but it does matter the size and the heat that the resistor can take. If you put a dinky sized resistor and crank up the current, it might not be able to handle the heat going thru it.


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