It all depends what you need the voltage for , and what you mean by extremely highFor safe high voltage no current experiments , a Van de Graaff Generator is a good alternative . A large modern one can reach 5 megavolts . A smaller tabletop version can easily reach 100 kilovolts . The current is virtually nonexistent . If you need some current , then there ' s other alternatives such as using a Microwave Oven Transformer in conjunction with a voltage multiplier stage such as a Marx ladderMarx generator . A warning to all reading Be aware , a MOT delivers ABSOLUTELY DEADLY current , easily . 5 A 2 kV , which is enough to kill you many many many times over . Playing with one is extremely dangerous , I would say even more dangerous than playing with live wires from a wall outlet . Unless you ' re familiar with handling HV equipment , do NOT fuck around with MOTs . Edit As an addition to the warning A safeish and fun way to have fun with MOTs is to remove the secondary winding very thin wire wrapped very many times and replace it with a very fat winding , but only a turn or two . Instead of high voltage and high current , you get very low voltage and extremely high current , which is pretty safe from an electrical point of view . Although , you can easily burn yourself on the stuff that you ' ll melt with it when having fun . Seriously , it will melt a nail in under a second .