Abstract: A pressure transducer for automobiles comprises a closed housing, a member for detecting the pressure in the suction pipe of an engine and converting the pressure detected into electric signals, an amplification circuit disposed in the closed housing, and an air passage. The air passage communicates with the atmosphere, but prevents water from penetrating therethrough into the closed housing. The air passage comprises an air hole formed in a member defining the closed housing about terminals provided for leading the electric signals out of the closed housing.

Abstract: An ignition circuit for use in an internal combustion engine comprises a magnet generator mechanically connected to a crank shaft of the engine. A first transistor is turned on and off by an alternating voltage signal from the magnet generator. A power transistor forms a closed circuit in cooperation with a high voltage transformer and a current source. The power transistor is controlled by a control signal from the first transistor so as to form a primary current which is abruptly cut off. The transformer induces a high voltage which is supplied for a spark plug in response to abrupt interception of the primary current. A delay element composed of a resistor and a capacitor is connected to a base of the first transistor.

Abstract: A semiconductor ignition system having a pick-up device for producing a.c. signals according to the speed of an engine, an ignition coil with a primary and secondary winding, a detecting device for detecting the output of the pick-up device, a switching device for controlling current flow to the primary winding in accordance with the output of the detecting device, and a control arrangement responsive to the ouput of the pick-up device for controlling the detecting device so that sufficient current flows to the ignition coil during high speed operation of the engine.