Try this: place a block on the left side place a RS torch. one block in front of that place Repeater. one block in front RS one block right RS. one block back RS.. set the repeater to 4 ticks. This timer is also switchable. it can be turned on or off. need more delay? place a repeater next the one there. facing into the block.
If you have any questions my GT northstarr50 feel free to friend me.
