Place a redstone torch on the side of a block and place another block directly above it .Now on the block that you placed the torch on place redstone dust.You will see that the torch flickers from lit to unlit until it remains unlit until you disturb it. Now place redstone torches on both sides of the block that you placed the first torch. Place blocks on them and wait for 2 seconds then brake them and the torches that you places on the sides. The torch will keep flicking from on to off and won't burn out