Fm signal seeker for stereo

Claim 2

In an FM stereo radio receiver having a tuner search mechanism for varying the reception frequency of the receiver until deactuated, detector means for producing a first signal in response to the reception of FM broadcast signals having a predetermined strength, decoder means for producing a second signal in response to the reception of FM stereo broadcast signals, voltage source means for continuously producing a third signal, a trigger circuit having a pair of inputs and an output, the output connected to the search mechanism for deactuating the search mechanism when signals are received at both inputs, means connecting one input to receive the first signal, and means for selectively connecting the other input to receive the second signal or the third signal, whereby the search mechanism may be selectively deactuated in response to all FM broadcast signals having the predetermined strength or only FM stereo broadcast signals having the predetermined strength.

Claim 3

In an FM stereo radio receiver having a tuner search mechanism for varying the reception frequency of the receiver until deactuated, a trigger circuit including first and second transistors connected in series for deactuating the search mechanism only when both the first and second transistors are biased conductive, detector means connected to the first transistor for biasing the first transistor conductive in response to the reception of FM broadcast signals having a predetermined strength, a DC power supply, a stereo indicator lamp, a third transistor connected between the power supply and the lamp for energizing the lamp from the power supply when rendered conductive, decoder means connected to the third transistor for biasing the third transistor conductive in response to the reception of FM stereo broadcast signals, and switching means selectively operable between first and second positions, the switching means connected between the second transistor and the power supply for biasing the second transistor conductive from the power supply when the switching means is in the first position, and the switching means connected between the second transistor and the third transistor for biasing the second transistor conductive from the power supply through the third transistor when the switching means is in the second position, whereby the search mechanism may be selectively deactuated in response to all FM broadcast signals having the predetermined strength or only FM stereo broadcast signals having the predetermined strength.

Claim 4

In an FM stereo radio receiver having a tuner search mechanism for varying the reception frequency of the receiver until deactuated, a trigger circuit including first and second transistors connected in series for deactuating the search mechanism only when both the first and second transistors are biased conductive, detector means connected to the first transistor for biasing the first transistor conductive in response to the reception of FM broadcast signals having a predetermined strength, a DC power supply, a stereo indicator lamp, a third transistor connected between the power supply and the lamp for energizing the lamp from the power supply when rendered conductive, decoder means connected to the third transistor for biasing the third transistor conductive in response to the reception of FM stereo broadcast signals, and switching means selectively operable between first and second positions, the switching means connected between the second transistor and the power supply for biasing the second transistor conductive from the power supply when the switching means is in the first position, and the switching means connected between the second transistor and the third transistor for biasing the second transistor conductive from the power supply through the third transistor when the switching means is in the second position, whereby the search mechanism may be selectively deactuated in response to all FM broadcast signals having the predetermined strength or only FM stereo broadcast signals having the predetermined strength.