So being curious, I opened up my cheapo radioshack battery powered soldering iron and to my surprise there was basically just a resistor and a contact switch which connected to the batteries and the soldering tip. Does this seem correct or am I mistaken. My purpose for opening it is because the temp. on the iron is way too high and I am trying to lower it to an appropriate range (~200 C) I think right now it is around 500 C. Could I just increase the resistance in order to decrease the power that is going to the soldering tip? If so how would I go about calculating the amount of resistance necessary to get the required temp? I am a little rusty on the physics of electricity but trying to get back into, so any help in the right direction would be much appreciated. Feel free to reference relevant equations, as I said I need to restudy some of these things. I'm not sure if this is right but the resistor appears to be 51 ohm, and there are four AA batteries which means 6V.