Not sure what kind of transfomer I should use...... Hello. I am trying to build a high-voltage DC transformer for a project (using a disruptor). I will be using a battery for the power (probably a 9v or 12v). I have done some reading about the different kinds of transformers used, and I am confused as to which one would be best for this. I was originally going to use a toroid-core transformer, however, because I'm not using AC I feel that there will be some residual magnetic field trapped in the core, or rather the core will become magnetized. I then considered an air-core transformer, but I'm not sure if this will severely reduce efficiency. Would it be theoretically possible to combine both by wrapping wire around a flexible non-metal tube, and then bending that into a torus? I'm not really looking for a stable source of high voltage output, but a high peak, if that helps.