For example, take a bug zapper. They are actually rather simple devices. In short, they kill insects with ... (that seems rather obvious). Voltage is supplied to two mesh wires via a transformer.

The bug zapper is encased in cardboard, with the computer fan operating as a means to suck the bugs into a Cold Cathode Fluorescent Lamp Inverter (CCFL) pulled out of an old scanner.

The bug zapper, pictured, was made by Raymond Van Orsoy de Flines, ... He said: 'The wasp zapper runs on 5600 Volts DC supplied via a microwave oven transformer and voltage doubler.