Pulse stretcher for a receiver of a pneumatic tire low pressure monitoring and warning system

Claim 1

A pneumatic tire low pressure monitoring and warning system comprising, means sensing a low pressure condition in a pneumatic tire supported on an associated vehicle by a rotatable support, a transmitter carried by and being rotatable with said rotatable support with said transmitter being actuated by said sensing means and providing output signals at a radio frequency in response to said low pressure condition; a receiving antenna attached at a fixed position on said vehicle adjacent said tire; said antenna receiving useable ones of said output signals only during a portion of each complete rotation of said transmitter therepast; a receiver; means operatively connecting said receiving antenna to said receiver; indicating means operatively connected to said receiver and being activated thereby; and means in said receiver for increasing the effective time duration of said useable ones of said output signals, said increasing means assuring said indicating means is activated only in response to said low pressure condition and comprising, an NPN transistor having base, collector, and emitter electrodes, a cooperating PNP transistor having base, collector, and emitter electrodes, said PNP transistor having its collector electrode connected to said indicating means and a positive feedback circuit connecting said collector electrode of said PNP transistor to said base electrode of said NPN transistor, each useable signal being supplied to said base of said NPN transistor and operating to turn said PNP transistor ON and simultaneously supply a voltage through said collector electrode of said PNP transistor to activate said indicating means, each useable signal being increased in effective time duration due to hysteresis of said feedback circuit, time delay in reduction in potential of said base of said PNP transistor, and time delay introduced by said feedback circuit.