Transistor amplifying circuit

Claim 2

A transistor amplifying circuit having input and output means and a power source, comprising a first transistor of grounded emitter type having a base applied with input signal from said input means; a second transistor having an emitter connected to a collector of said first transistor in a D.C. conductive relationship to each other and a collector connected to said power source; bias circuits connected to respective bases of said first and second transistors, one of said bias circuits for said second transistor comprising high impedance elements; a capacitor having a value of capacitance sufficient to provide a relatively lower impedance for an input signal applied to said first transistor and connected between said base of said second transistor and the junction point of said collector of said first transistor and one end of D.C. conductive means with the other end connected to said emitter of said second transistor so that the output signal from said first transistor is substantially shunted from being applied across said base and said emitter of said second transistor; and a variable resistor connected between said collector of said first transistor and a ground to receive and control said output signal from said first transistor and to output the thus controlled signal to said output means, said variable resistor arranged so that the value of resistance between said junction point and said ground can vary whereby the amplitude of the output signal at said output means is substantially proportional to the value of resistance of said variable resistor between said junction point and said ground with the output impedance of said first transistor at said junction point having a value sufficiently higher than the value of resistance of said variable resistor.

Claim 3

A transistor amplifying circuit as set forth in claim 1, and wherein said variable resistor has both ends connected to said output means and a variable terminal connected to said collector of said first transistor.

Claim 4

A transistor amplifying circuit as set forth in claim 1, and wherein said variable resistor has both ends connected to said output means and a variable terminal connected to said ground.

Claim 5

A transistor amplifying circuit as set forth in claim 1, and wherein said variable resistor has one of the ends connected to said ground and a variable terminal connected both to said collector of said first transistor and to said output means.

Claim 6

A mixing circuit comprising a mixing transistor and a plurality of transistor amplifying circuits, each of said transistor amplifying circuits having input and output means and a power source, said output means of said transistor amplifying circuits associated with a base of said mixing transistor, characterized by that each of said transistor amplifying circuits comprises a first transistor of grounded emitter type having a base applied with input signal from said input means; a second transistor having an emitter connected to a collector of said first transistor in a D.C. conductive relationship to each other and a collector connected to said power source; bias circuits connected to respective bases of said first and second transistors one of said bias circuits for said second transistor comprising high impedance elements; a capacitor having a value of capacitance sufficient to provide a relatively lower impedance for an input signal applied to said first transistor and connected between said base of said second transistor and the junction point of said collector of said first transistor and one end of D.C. conductive means with the other end connected to said emitter of said second transistor so that the output signal from said first transistor is substantially shunted from being applied across said base and said emitter of said second transistor; a variable resistor having one of the fixed terminals connected to said base of said mixing transistor and the other fixed terminal connected to a ground, said mixing transistor constituting the output of said mixing circuit, said variable resistor furtHer having the variable terminal connected to said junction point so that the value of resistance between said junction point and said ground can vary, whereby said mixing circuit mixes the output signals from respective transistor amplifying circuits, said output signals proportional to the respective values of resistance of said respective variable resistors between said junction points and said grounds, respectively, by the respective output impedances of said transistor amplifying circuits at said output means thereof maintained substantially constant regardless of the positions of said variable terminals of said respective variable resistors.

Claim 7

A mixing circuit comprising a mixing transistor and a plurality of transistor amplifying circuits, each of said transistor amplifying circuits having input and output means and a power source, said output means of said transistor amplifying circuits associated with a base of said mixing transistor, characterized by that each of said transistor amplifying circuits comprises a first transistor of grounded emitter type having a base applied with input signal from said input means; a second transistor having an emitter connected to a collector of said first transistor in a D.C. conductive relationship to each other and a collector connected to said power source; bias circuits connected to respective bases of said first and second transistors one of said bias circuits for said second transistor comprising high impedance elements; a capacitor having a value of capacitance sufficient to provide a relatively lower impedance for an input signal applied to said first transistor and connected between said base of said second transistor and the junction point of said collector of said first transistor and one end of D.C. conductive means with the other end connected to said emitter of said second transistor so that the output signal from said first transistor is substantially shunted from being applied across said base and said emitter of said second transistor; a variable resistor having one of the fixed terminals connected to said base of said mixing transistor and the other fixed terminal connected to a ground, said mixing transistor constituting the output of said mixing circuit, said variable resistor furtHer having the variable terminal connected to said junction point so that the value of resistance between said junction point and said ground can vary, whereby said mixing circuit mixes the output signals from respective transistor amplifying circuits, said output signals proportional to the respective values of resistance of said respective variable resistors between said junction points and said grounds, respectively, by the respective output impedances of said transistor amplifying circuits at said output means thereof maintained substantially constant regardless of the positions of said variable terminals of said respective variable resistors.