Hi Ace,

Thanks for your reply.

The button is pressed by the piston on a gear box. As i said on other post, my actual reading is 15 to 20 cycles per sec. And i need to stop the piston, after 3 cycles.

I have some Ir sensors. But putting them inside the gearbox or some where around, it is not a good idea.

Hence, buttons is the best for my application i think.

Thanks.