Abstract The present invention provides a continuity tester comprising a D.C. coupled amplifier for providing a voltage to a transducer through a voltage threshold means, an A.C. attenuator for providing positive feedback to the amplifier, a first resistor connected between the input and the output of the amplifier and a second resistor connected in series with the transducer between the input and the output of the amplifier, the first and second resistors providing negative feedback to the amplifier, and means for connecting a circuit to be tested in parallel across the second resistor, whereby if the impedance of the test circuit is below a predetermined value, the amplifier becomes unstable and causes the transducer to produce a signal whose frequency is dependent on the impedance of the test circuit.
A continuity tester comprising a D.C. coupled amplifier for providing a voltage to a transducer through a voltage threshold, an A.C. attenuator for providing positive feedback to the amplifier, a first resistor connected between the input and the output of the amplifier and a second resistor connected in series with the transducer between the input and the output of the amplifier, the first and second resistors providing negative feedback to the amplifier and forming a bridge circuit, and means for connecting a circuit to be tested in parallel across the second resistor of said bridge circuit, whereby if the impedance of the test circuit is below a predetermined value, the amplifier becomes unstable and causes the transducer to produce a signal whose frequency is dependent on the impedance of the test circuit.
Claim 2
Dependent Claim
132 words
A continuity tester comprising a D.C. coupled amplifier for providing a voltage to a transducer through a voltage threshold, an A.C. attenuator for providing positive feedback to the amplifier, a first resistor connected between the input and the output of the amplifier and a second resistor connected in series with the transducer between the input and the output of the amplifier, the first and second resistors providing negative feedback to the amplifier and forming a bridge circuit, and means for connecting a circuit to be tested in parallel across the second resistor of said bridge circuit, whereby if the impedance of the test circuit is below a predetermined value, the amplifier becomes unstable and causes the transducer to produce a signal whose frequency is dependent on the impedance of the test circuit.
Claim 3
Dependent Claim
15 words
A continuity tester according to claim 1, in which the transducer produces an audible signal.
Claim 4
Dependent Claim
16 words
A continuity tester according to claim 1, in which the D.C. coupled amplifier comprises two transistors.
Claim 5
Dependent Claim
16 words
A continuity tester according to claim 2, in which the D.C. coupled amplifier comprises two transistors.