Abstract: A device for shutting off or stopping a marine engine ignition system utilizing a transmitter for generating a wireless signal. The wireless signal is only generated upon association of the transmitter with a mass of water. A receiver acquires the wireless signal and generates a disconnection signal which interrupts the operation of a marine engine.

Abstract: A device for shutting off or stopping a marine engine ignition system utilizing a transmitter for generating a wireless signal. The wireless signal is only generated upon association of the transmitter with a mass of water. A receiver acquires the wireless signal and generates a disconnection signal which interrupts the operation of a marine engine.

Abstract: A system to prevent injuries due to marine propellers striking swimmers and other persons in the water next to a boat utilizing a switch. The switch is normally in a closed position and is only opened when a movable element such as a ladder, gate, and the like on the boat travels to an unlatched position. Such movement interrupts the ignition circuit of the boat motor. An override device is also employed to allow normal operation of the marine engine and requires both mechanical and electrical interconnection or matting of connector elements.

Abstract: An optical sensor system (10) in the form of a hand held tonometer probe has an infrared emitting diode (34) and a phototransistor detector (36) positioned to receive light from the diode (34). A rod (18) serves as a variable attenuator to intercept a portion of light from the diode (34) directed at the detector (36). A signal level detecting amplifier (104) is coupled to the detector (36) to receive an output signal from the detector (36) in response to light from the diode (34) received by the detector (36). The amplifier (104) has a non-inverting input (102) and an inverting input (106). The amplifier (104) receives the output signal from detector (36) at non-inverting input (102). A +5 volt reference potential is connected through a variable resistor (110) and a resistor (108) to establish a bias at the inverting input (106) which is approximately equal to signal levels supplied by the detector (36) to the non-inverting input (102).