Model T Ford Spark coils. The ORIGINAL "coil on plug" or "coil near plug" ignition. They have a buzzer device, and when supplied with power, will generate a continuous spark. When I was young---10? ish? I used to "rig" a T coil we had to my train transformer, and go out on the little sidewalk and "lightning bolt" insects. It would REALLY destroy an ant with a good hit