Here is another schematic then.http://picasaweb.google.com/lh/photo/k5cWgoCDzPIL3k5zubNA8T2qwst-Qvyrn_-T3i-6zWM?feat=directlink I believe eventually the signal will die out and will fade as time goes on. I have just built the circuit and it works perfectly. I have been waiting for 15 minutes and the signal has still not gone out. Instead of unplugging the supply I would suggest you just put a push button across that shorts the capacitor terminals together so it can drain instantly and shut off the signal. If you really wanted it to shut off by removing the power source alone i don't know if that would work for this setup. You would need to wait for the capacitor to drain. I think the push button is just more convenient than having to unplug the supply.