I'm using a wire foam cutter where the bridge wire heats up on a low DC voltage but it is not getting hot enough. The unit is 240v converted to 5v in a plug in transformer which simply runs up to the cutting wire. the wire was 0.23mm gauge and I've tried 0.21mm, expecting the resistance to be more, thus creating more heat, but there seems to be no change. looking for a cheap solution as once done with it will be binned.

* Should maybe add the power output is 2a and the wire cutter is 8.7w.

 

You have to decrease the resistance at the same voltage to increase the power. (heat)

 

Decrease the resistance? I was thinking the resistance was creating the heat therefore more resistance more heat, same as with using underrated wire.

 

Decrease the resistance? I was thinking the resistance was creating the heat therefore more resistance more heat, same as with using underrated wire.

Well figure it this way. Look at the relationship between Voltage and Current with Resistance. Your wire has a fixed resistance so that doesn't change. Let's call your hot wire 2.0 Ohms. The only way to increase the heat is to increase the current through the 2.0 Ohm load. If we increase the voltage with the fixed load resistance the current will increase proportional to the voltage increase. Apply Ohms Law. Your wire resistance can't change unless you use a lower resistance wire or you make the hot wire shorter. That only leaves increasing the applied voltage.

Next, consider your power source needs to be able to deliver enough voltage and current to your load, the hot wire. Consider also as your hot wire gets hot the resistance of the wire will increase.

Ron

 

Decrease the resistance? I was thinking the resistance was creating the heat therefore more resistance more heat, same as with using underrated wire.

Well, you can think anything you want.

Power is voltage times current expressed in watts.

Therefore, if you decrease the resistance, you increase the current.

Since you have a fixed 5 volts the only way to increase power is to decrease the resistance.

The alternative as stated by Ron is to increase the voltage.

 

Well, you can think anything you want.

Power is voltage times current expressed in watts.

Therefore, if you decrease the resistance, you increase the current.

Since you have a fixed 5 volts the only way to increase power is to decrease the resistance.

The alternative as stated by Ron is to increase the voltage.

The explanation left out only one thing, which is that it is the POWER that makes the heat. More specificly, it is the power in the wire that heats the wire.

 

The explanation left out only one thing, which is that it is the POWER that makes the heat. More specificly, it is the power in the wire that heats the wire.

This is why I thought if you can't increase the power to make more heat you could reduce the wire gauge to increase it? Found an old 12v power unit with a viriable supply dial so will try that tomorrow. If it burns out the wire then I guess I will have to recalculate what I can use and buy some more.

 

This is why I thought if you can't increase the power to make more heat you could reduce the wire gauge to increase it? Found an old 12v power unit with a viriable supply dial so will try that tomorrow. If it burns out the wire then I guess I will have to recalculate what I can use and buy some more.

Your wire is likely Nichrome wire, I suggest you look up the resistance charts for Nichrome wire. Wire gauge is about the wire diameter or more specific the cross sectional area of the wire. The higher the wire gauge the smaller the diameter and cross sectional area of the wire. Just keep in mind applying 12 VDC or 0 to 12 VDC means nothing unless the supply can deliver the required current. Note the length of your hot wire and based on gauge calculate the resistance so you know about how much current your wire will draw at various voltages. Apply basic ohms law and make sure your power supply can deliver the calculated current and then some.

Ron