I actually made a spark gap "receiver" when I was a kid following some plans I found. I used a rubber tube with a metal rod in one end, then filled partially wi

I actually made a spark gap "receiver" when I was a kid following some plans I found. I used a rubber tube with a metal rod in one end, then filled partially with iron filings I made from filing a pipe, then stuck another metal rod to plug the other end of the tube slightly compressing the filings. I then placed a LED, resistor and battery in series with the device. If the LED turns on, flick the device until it is off. Then place next to my gas stove and click the gas spark igniter. If all goes well, the spark will iron align some of the iron filings to create a conductive path and the LED will turn on. Flick again to turn off.