Priority interrupt circuit

• US 4,105,974 A
• Filed: 10/14/1975
• Issued: 08/08/1978
• Est. Priority Date: 10/14/1975
• Status: Expired due to Term

• Current Assignee: Edwin F. Rogers
• Original Assignee: Edwin F. Rogers
• Inventors: Rogers, Edwin F.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/621,823
• Time in Patent Office: 1,029 Days
• Field of Search: 325/21, 325/22, 325/57, 325/303, 325/304, 325/466, 325/18, 325/15, 343/227, 343/228, 343/205, 343/207, 179/1 SW, 179/1 VC, 179/1 CN
• US Class Current: 455/88
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A priority interrupt circuit for inhibiting the supply of signals from a first audio signal source to an electroacoustic transducer and substituting therefore signals from a second audio signal source in response to the occurrence of signals from the second source and despite the continued availability of signals from the first source is disclosed having the further capability of effecting the substitution of the second source for the first source when a radio frequency transmitter is enabled.

Claims

1. A priority interrupt system comprising:

at least one electroacoustic transducer;

a first audio signal source for supplying audio frequency signals to the transducer;

a second audio signal source;

means for monitoring the second audio signal source for the presence of any audio frequency signals, the means for monitoring including a capacitor and diode means coupled to the second audio signal source for charging the capacitor when audio frequency signals are present;

means responsive to detection by the monitoring means of an audio frequency signal to diminish the magnitude of audio frequency signals supplied to the transducer from the first audio signal source, the responsive means responding to the voltage on the capacitor exceeding a specified value, the responsive means further comprising a resistor connected in parallel with the capacitor to slowly discharge the capacitor to thereby disable the responsive means and reestablish the undiminished supply of audio frequency signals from the first source to the transducer in the absence of audio frequency signals from the second source for a predetermined time interval; and

a radio frequency transmitter, the means for monitoring further adapted to sense signals from the radio frequency transmitter and to cause the said capacitor to charge and the said responsive means to diminish the magnitude of audio frequency signals supplied to the transducer from the first audio signal source when radio frequency signals are detected.

2. The system of claim 1 wherein said responsive means is effective to completely disconnect the first audio signal source from the transducer.

3. The system of claim 2 further comprising means associated with the said responsive means for coupling the second audio signal source to the transducer when the first audio signal source is disconnected from the transducer.

4. The system of claim 1 wherein the capacitor may slowly discharge through the parallel connected resistor only in the absence of both an audio frequency signal from the second source and a radio frequency signal from the radio frequency transmitter.

5. In a system including a radio frequency transmitter, an electroacoustic transducer, and an audio signal source for supplying audio frequency signals to the transducer, the improvement comprising:

means monitoring the transmitter for the presence of radio frequency output signals, the means for monitoring including a capacitor, and diode means coupled between the radio frequency transmitter and the capacitor for charging the capacitor when the radio frequency transmitter is producing radio frequency output signals;

means coupled to the monitoring means and operable when enabled thereby to diminish the magnitude of the audio frequency signals supplied to the transducer; and

an intermittent audio frequency signal source, radio frequency choke means coupling the diode means to the intermittent audio frequency signal source whereby the occurence of an audio frequency signal will also diminish the magnitude of the audio frequency signals supplied from the audio signal source to the transducer, the radio frequency choke means preventing the loading of the radio frequency transmitter output by the intermittent audio frequency signal source.

6. A priority interrupt circuit for first and second audio signal sources and a radio frequency transmitter comprising:

first means for normally coupling the first audio signal source to an electroacoustic transducer;

second means for monitoring the second audio signal source and the radio frequency transmitter for the presence of respective audio frequency signals and radio frequency signals; and

means responsive to the sensing of the presence of a respective signal by the second means for controlling the first means to uncouple the first audio signal source from the transducer.

7. The priority interrupt circuit of claim 6 wherein the first means comprises a coil actuated relay with normally closed contacts interconnecting the first audio signal source and the electroacoustic transducer.

8. The priority interrupt circuit of claim 7 wherein the responsive means comprises a semiconductor switching device connected in series with the relay actuating coil and having a control electrode coupled to the second means.

9. The priority interrupt circuit of claim 8 wherein the semiconductor switching device is a Darlington amplifier.

10. The priority interrupt circuit of claim 8 wherein the second means comprises a capacitor, and diode means coupled to the second audio source and to the radio frequency transmitter for charging the capacitor when respective signals are present, the voltage across the capacitor being applied to the semiconductor switching device control electrode to cause the semiconductor switching device to conduct and energize the relay when the capacitor voltage exceeds a predetermined value.

11. The priority interrupt circuit of claim 10 further comprising a resistor connected in parallel with the capacitor to slowly discharge the capacitor, the time constant for charging the capacitor in response to the occurrence of a respective signal being substantially less than the time constant for discharging the capacitor through the resistor in the absence of a respective signal.