Headphone type FM stereo receiver

Claim 2

An FM stereo signal demodulator for FM stereo receivers comprising a first transistor having its base connected to receive an FM stereo signal from said discriminator, a 19 KC tuning coil connected to the collector of said first transistor, frequency multiplying diodes connected to the secondary winding of said tuning coil, a direct coupled amplifier consisting of second and third transistors, the emitter of said third transistor being connected to the base of said second transistor through more than one resistor so as to obtain the bias of said second transistor, and to obtain the negative feedback loop for the amplifier composed of said second and third transistors, and a switchng circuit consisting of four diodes connected in the shape of a ring, the arrangement being such that a signal received by the 19 KC tuning coil is multiplied to a 38 KC signal by the frequency multiplying diodes, the resultant 38 KC signal being impressed on the direct-coupled amplifier to obtain 38 KC outputs of opposite polarities from the emitter and collector of the third transistor, and said 38 KC output being coupled with a stereophonic signal supplied from the first transistor and then impressed on a pair of connections located at opposite ends of one of the diagonal lines of the switching circuit, whereby separated left and right signals are taken out from opposite ends of another diagonal line of said switching circuit.

Claim 3

A headphone type FM stereo receiver accommodating a tuner including an antenna for receiving FM stereophonic broadcasting, an IF amplifier, a discriminator, an FM stereo signal demodulator, a left and right audio frequency amplifier and power source means for supplying electric power to said respective elements in a headphone composed of a left and a right phone case and a head belt bridging said phone cases with each other, said receiver being capable of receiving FM stereophonic broadcasting without being connected to an external apparatus, wherein said FM stereo signal demodulator comprises a first transistor having its base connected to receive an FM stereo signal from said discriminator, a 19 KC tuning coil connected to the collector of said first transistor, frequency multiplying diodes connected to the secondary winding of said tuning coil, a direct-coupled amplifier consisting of second and third transistors, the emitter of said third transistor beIng connected to the base of said second transistor through more than one resistor so as to obtain the bias of said second transistor, and to obtain the negative feedback loop for the amplifier composed of said second and third transistors, and a switching circuit consisting of four diodes connected in the shape of a ring, the arrangement being such that a signal received by the 19 KC tuning coil is multiplied to a 38 KC signal by the frequency multiplying diodes, the resultant 38 KC signal being impressed on the direct-coupled amplifier to obtain 38 KC outputs of opposite polarities from the emitter and collector of the third transistor, and said 38 KC outputs being coupled with a stereophonic signal supplied from the first transistor and then impressed on a pair of connections located at opposite ends of one of the diagonal lines of the switching circuit, whereby separated left and right signals are taken out from opposite ends of another diagonal line of said switching circuit.

Claim 4

A headphone type FM stereo receiver accommodating a tuner including an antenna for receiving FM stereophonic broadcasting, an IF amplifier, a discriminator, an FM stereo signal demodulator, a left and right audio frequency amplifier and power source means for supplying electric power to said respective elements in a headphone composed of a left and a right phone case and a head belt bridging said phone cases with each other, said receiver being capable of receiving FM stereophonic broadcasting without being connected to an external apparatus, wherein said FM stereo signal demodulator comprises a first transistor having its base connected to receive an FM stereo signal from said discriminator, a 19 KC tuning coil connected to the collector of said first transistor, frequency multiplying diodes connected to the secondary winding of said tuning coil, a direct-coupled amplifier consisting of second and third transistors, the emitter of said third transistor beIng connected to the base of said second transistor through more than one resistor so as to obtain the bias of said second transistor, and to obtain the negative feedback loop for the amplifier composed of said second and third transistors, and a switching circuit consisting of four diodes connected in the shape of a ring, the arrangement being such that a signal received by the 19 KC tuning coil is multiplied to a 38 KC signal by the frequency multiplying diodes, the resultant 38 KC signal being impressed on the direct-coupled amplifier to obtain 38 KC outputs of opposite polarities from the emitter and collector of the third transistor, and said 38 KC outputs being coupled with a stereophonic signal supplied from the first transistor and then impressed on a pair of connections located at opposite ends of one of the diagonal lines of the switching circuit, whereby separated left and right signals are taken out from opposite ends of another diagonal line of said switching circuit.