I have been building a electric lighter without soldering since I don't know how to solder, so I am going to ask my brother to show me how on the weekend. Until then I've been using alligator clips, 9 volt batteries (preferably one) and graphite from pencils as a resistor. Unfortunately the mechanical pencil resistors break easily and now I'm using pencil resistors and I am now struggling to find what length of resistor I need. I do have a voltmeter but I think it is damaged since it can't measure voltage accurately or measure resistance at all. Can one of you show me how to calculate the resistance needed and how to calculate the length needed. I am using an HB pencil and I want to simply light paper on fire.