Tone detector control circuit

Claim 2

An alternating current level detector having a direct current output comprising: a source of operating potential, a first transistor of a first conductivity type and a second transistor of the opposite conductivity type, each connected in an operating circuit to said source of operating potentials, a bias means connected in said first transistor operating circuit, said second transistor connected to said bias means for operatively biasing said second transistor upon conduction by said first transistor, a feedback means including a capacitor connected from said second transistor to said first transistor, signal input means coupled to the first-transistor side of said capacitor in said feedback means opErative to render said first transistor conductive upon the application of an AC signal via said input means, means including the continued presence of a signal via said input means and said capacitor to maintain both said transistors in the conductive state, and output means connected to said second transistor effective upon operation of said second transistor to present a direct current potential thereon.

Claim 3

An alternating current level detector as claimed in claim 1 wherein said output means includes rectifier means for isolating external conditions from said second transistor.

Claim 4

An alternating current level detector as claimed in claim 2 wherein said first transistor is of a PNP-conductivity type and said second transistor is of an NPN-conductivity type.

Claim 5

An alternating current level detector as claimed in claim 1 wherein said first transistor is of a PNP-conductivity type and said second transistor is of an NPN-conductivity type.

Claim 6

In a system wherein predetermined frequencies and magnitudes of alternating current signals are utilized to automatically activate auxiliary apparatus, an automatic switching control circuit comprising: signal input means, a positive and a negative source of energizing potential, a frequency-discriminating means having an output and an input means, said input means connected to said signal input means, an alternating current level detecting means comprising, a first and a second PNP- and a third NPN-transistor, each said transistor having a base, an emitter and a collector electrode, means coupling said base electrode of said first transistor to said frequency-discriminating means output, biasing means coupled to the base and emitter electrodes of said first PNP-transistor to effect class C operation thereof upon the application of a signal from said signal input means through said frequency-discriminating means, and a circuit configuration comprising, means connecting said second PNP-transistor emitter to said positive energizing source, a first resistor connected to said PNP-transistor collector, a second resistor serially connected between said first resistor and said negative source, a third resistor and a capacitor serially connected between said second PNP-transistor base and said NPN-transistor collector, a first diode means connected with its cathode end to the positive source and its anode end to the base of said second PNP-transistor, a second diode means with its anode connected to the emitter of said third NPN-transistor and its cathode end connected to said negative source, means connecting the base of said NPN-transistor to the junction of said first and second resistors to bias said third transistor into a conductive state upon said second transistor conducting, means coupling said first transistor collector to the connection between said third resistor and said capacitor to operate said second transistor to a conductive state, whereby said third transistor is turned on, and output means coupled to said third transistor collector effective to present a direct current output to auxiliary apparatus.

Claim 7

In a system wherein predetermined frequencies and magnitudes of alternating current signals are utilized to automatically activate auxiliary apparatus, an automatic switching control circuit comprising: signal input means, a positive and a negative source of energizing potential, a frequency-discriminating means having an output and an input means, said input means connected to said signal input means, an alternating current level detecting means comprising, a first and a second PNP- and a third NPN-transistor, each said transistor having a base, an emitter and a collector electrode, means coupling said base electrode of said first transistor to said frequency-discriminating means output, biasing means coupled to the base and emitter electrodes of said first PNP-transistor to effect class C operation thereof upon the application of a signal from said signal input means through said frequency-discriminating means, and a circuit configuration comprising, means connecting said second PNP-transistor emitter to said positive energizing source, a first resistor connected to said PNP-transistor collector, a second resistor serially connected between said first resistor and said negative source, a third resistor and a capacitor serially connected between said second PNP-transistor base and said NPN-transistor collector, a first diode means connected with its cathode end to the positive source and its anode end to the base of said second PNP-transistor, a second diode means with its anode connected to the emitter of said third NPN-transistor and its cathode end connected to said negative source, means connecting the base of said NPN-transistor to the junction of said first and second resistors to bias said third transistor into a conductive state upon said second transistor conducting, means coupling said first transistor collector to the connection between said third resistor and said capacitor to operate said second transistor to a conductive state, whereby said third transistor is turned on, and output means coupled to said third transistor collector effective to present a direct current output to auxiliary apparatus.

Claim 8

In a system as claimed in claim 5 wherein said output means includes rectifier means for isolating external conditions from said third transistor.

Claim 9

In a system as claimed in claim 6 further including a second automatic switching control circuit as claimed in claim 6 for the first said control circuit but responsive to another frequency and means connecting said output means of each said control circuit together whereby either of said control circuits may activate said same external apparatus.

Claim 10

In a system as claimed in claim 7 wherein said second control circuit further includes diode means with the anode end connected to said third transistor base and said cathode end to said third transistor collector of said first control circuit.