How do you increase a voltage?

If you are dealing with AC voltage, you can use a transformer. You can find Transformers at places like Radio Shack, Jaycar and some online sites like eBay. Transformers have to be connected in the right way. You have to connect the voltage you are going to increase to the low voltage side and on the high voltage side will be the voltage which has been stepped up by the transformer. (If you want a DC voltage out, you will need to connect a bridge rectifier to the output, followed by a large capacitor and then a voltage regulator of the voltage you want out.)

If you are dealing with DC voltage then you will need a chip to step the voltage up. These chips can step voltage up from around 1 to 10 volts to at least 20 to 30 volts. These chips also need to be connected correctly. You will need more components than using a transformer. You will probably need some capacitors and some resistors. Depending on the IC you choose, you will find many circuits on google for it and how to build them.

By far the easiest type of voltage to step up is AC. If you have the option of AC, and need to have a very high voltage output, you are better off using a transformer, bridge rectifier and a rectifier.