I understand how they work, and I am thinking of using one on my big planes. It would be a secondary way of killing an engine other than a throttle servo.

But how does the switch sense a loss of signal when there is a failsafe pre-programmed at the receiver end? I mean, If the receiver goes to low throttle during a failsafe event, how does the switch know that the receiver went to low throttle because of a loss of signal? That is the part I do not understand; the automatic part. I would definitely program the failsafe at the receiver to activate the channel to kill the engine via the opto-switch, but raptureboy said that the switch reacts to singal loss as a feature of the switch not a feature of pre-programmed failsafe. Am I totally off base here?

Rafael