Here's how it works: there is a switch on the end of a wire. When you turn the switch on, it charges a capacitor, and turns on a transistor, which turns on an optotriac, which ignites a triac, which turns on the light. When you flip the switch off, the capacitor begins to deplete, allowing the lamp to stay on for about 20 seconds. The main-voltage and low-voltage parts of the circuit is electrically separated from each other. The delay-circuit get the power from the microwave oven (it was there already). Unfortunately, I only found 12V in the microwave, so I threw in a 7805 circuit later. There is also a snubber circuit, since there is a coil in neon lamps, and thus I consider it an "inductive load". The whole thing fits in a small plastic box, and hides behind the microwave. It works perfectly, and it was also a great opportunity for me to learn the basics of a triac.