A.C. power supply circuit in combination with an A.C. source and a D.C. source

• US 3,925,772 A
• Filed: 06/27/1974
• Issued: 12/09/1975
• Est. Priority Date: 06/27/1974
• Status: Expired due to Term

• Current Assignee: Gail R. Nielsen, Lowell E. Miller
• Original Assignee: Gail R. Nielsen, Lowell E. Miller
• Inventors: Miller, Lowell E., Nielsen, Gail R.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US05/483,635
• Time in Patent Office: 530 Days
• Field of Search: 340/253C,333 307/44,45,46,48,64,66,80 315/86 321/45R 331/113A
• US Class Current: 340/636.15
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 7/53806 in a push-pull configuration of the parallel type

Abstract

An A.C. power supply circuit for use with an A.C. source and a battery includes a full-wave rectifier for rectifying the A.C. signal produced by the A.C. source, a battery supply control circuit responsive to a control signal for coupling the battery to the output of the rectifier, an A.C. sensing circuit for applying a control signal to the battery supply control circuit if the amplitude of the signal produced by the A.C. source falls below a predetermined level, and an oscillator circuit for producing an oscillatory signal in response to the signal present on the output of the rectifier. A battery sensing circuit is also included for producing a second control signal if the charge on the battery falls below some predetermined level. In response to this second control signal, a battery charge circuit applies a rectified A.C. signal from the A.C. source to the battery. If the charge on the battery falls below a second lower predetermined level, a shutdown circuit applies a signal to the battery supply control circuit to prevent the control circuit from connecting the battery to the output of the rectifier.

Claims

1. An A.C. power supply circuit in combination with an A.C. source and a D.C. source for producing an oscillatory output in response to signals either from the A.C. source, the D.C. source, or both, said power supply circuit comprising a first rectifier for rectifing the A.C. signal produced by the A.C. source, a control circuit responsive to a control signal for coupling the D.C. source to the output of said rectifier, an A.C. sensing circuit coupled to the A.C. source for applying a control signal to said control circuit if the amplitude of the signal produced by said A.C. source falls below a predetermined level, and an oscillator circuit coupled to the output of said rectifier for producing an oscillatory signal in response to the signal present on the output of said rectifier, whereby said power supply circuit produces a substantially continuous oscillatory signal by drawing power from the D.C. source to the extent the output on the A.C. source falls below said predetermined level.

2. A power supply circuit as in claim 1 further comprising a second rectifier coupled to said A.C. source for applying a rectified A.C. signal to said oscillator circuit to thereby cause said oscillator circuit to produce an oscillatory signal in synchronization with the signal produced by said A.C. source.

3. A power supply circuit as in claim 2 wherein said oScillator circuit comprises amplifier means coupled to the output of said first rectifier, output circuit means coupled to said amplifier means for producing an oscillatory signal, and feedback circuit means coupled to said output circuit for supplying a feedback signal from said output circuit to said amplifier means.

4. A power supply circuit as in claim 3 wherein said second rectifier includes a pair of diodes each of which conducts during alternate half cycles of the signal produced by the A.C. source, wherein said amplifier means includes a pair of transistors whose emitter electrodes are coupled to the output of said first rectifier and whose base electrodes are each coupled to a different one of said diodes, wherein said output circuit means includes a first transformer, a first winding of which is coupled between the collector electrodes of said pair of transistors, and wherein said feedback circuit means includes a second winding of said transformer inductively coupled to said first winding, one end of said second winding being coupled to the base electrode of one of said transistors and the other end of said second winding being coupled to the base electrode of the other of said transistors.

5. A power supply circuit as in claim 4 wherein said oscillator circuit further comprises a first pair of diodes coupled in parallel and in opposite directions between one end of said second winding and the base electrode of one of said transistors, and a second pair of diodes coupled in parallel and in opposite directions between the other end of said second winding and the base electrode of the other of said transistors.

6. A power supply circuit as in claim 5 wherein said first rectifier includes a second transformer, a first winding of which is coupled to said A.C. source, and a pair of diodes each coupled to different ends of a second winding of said second transformer, and wherein the power supply circuit further comprises a voltage regulator coupling a center tap of said second winding of said second transformer to a center tap of said first winding of said first transformer and to a center tap of said second winding of said first transformer.

7. A power supply circuit as in claim 2 wherein said control circuit comprises a power transistor whose emitter-collector circuit is coupled between said D.C. source and the output of said first rectifier, and means coupled to the base electrode of said power transistor and responsive to said control signal for biasing said power transistor into a conducting condition.

8. A power supply circuit as in claim 7 further comprising means for producing a visual indication when said biasing means biases said power transistor into a conducting condition.

9. A power supply circuit as in claim 2 wherein said A.C. sensing circuit comprises a third rectifier for rectifying the signal produced by said A.C. source, threshold detection means coupled to said third rectifier for producing an output signal each time the level of the rectified signal from the third rectifier exceeds a predetermined level, and first timing means coupled to said threshold detection means for generating said control signal if no output signal is received by the first timing from the threshold detection means within a predetermined period of time.

10. A power supply circuit as in claim 9 further comprising means for producing a visual indication if said control signal is generated.

11. A power supply circuit as in claim 9 wherein said A.C. sensing circuit further comprises a latching circuit responsive to said control signal for preventing reception by the first timing means of output signals produced by the threshold detection means.

12. A power supply circuit as in claim 11 wherein said A.C. sensing circuit further comprises a second timing means for producing a signal to disable said latching circuit a predetermined period of time after said control signal is generated.

13. A power supply circuit as in claim 12 wherein said first timing means comprises a capacitor chargeable by a voltage source, a first transistor whose base electrode is coupled to said threshold detection means and whose collector and emitter electrodes are coupled across said capacitor, said transistor being responsive to an output signal applied to the base electrode of the transistor from the threshold detection means for discharging the capacitor, and a differential amplifier responsive to the charge on said capacitor exceeding a predetermined level for generating said control signal.

14. A power supply circuit as in claim 13 wherein said latching circuit comprises a second transistor whose base electrode is coupled to the output of said differential amplifier and whose emitter-collector circuit couples the base electrode of said first transistor to ground, said second transistor being responsive to the generation of said control signal for conducting the output signals produced by said threshold detection means to ground.

15. A power supply circuit as in claim 14 wherein said second timing means comprises a second capacitor chargeable by the generation of said control signal, a second differential amplifier for producing an output signal when the charge on said second capacitor exceeds a predetermined level, and a third transistor whose base electrode is coupled to the output of said second differential amplifier and whose emitter-collector circuit couples the base electrode of said second transistor to ground, said third transistor being responsive to the output signal produced by the second differential amplifier for conducting to ground any control signal applied to the base electrode of said second transistor.

16. A power supply circuit as in claim 2 further comprising a D.C. sensing circuit coupled to said D.C. source for producing a charging control signal if the amplitude of the signal produced by said D.C. source falls below a predetermined level, and a charging circuit coupled between said A.C. source and said D.C. source and responsive to said charging control signal for applying a rectified A.C. signal to said D.C. source.

17. A power supply circuit as in claim 16 wherein said D.C. sensing circuit comprises a differential amplifier for producing an output signal when the amplitude of the signal produced by said D.C. source falls below a predetermined level, and oscillatory means responsive to the output signal of the differential amplifier and to the signal produced by the D.C. source for producing an oscillatory charging control signal.

18. A power supply circuit as in claim 17 further comprising means for producing a visual indication when said differential amplifier is producing no output signal.

19. A power supply circuit as in claim 17 wherein said oscillatory means includes a unijunction transistor whose base 2 electrode is coupled to said D.C. source, a capacitor coupled to the emitter electrode of said unijunction transistor, a resistor coupling said capacitor to said D.C. source, a second transistor whose emitter-collector circuit couples the emitter of said unijunction transistor to ground, and whose base electrode is coupled to the output of said differential amplifier, said second transistor being responsive to the absence of an output signal from said differential amplifier for preventing the charging of said capacitor and being responsive to an output signal from said differential amplifier for enabling the charging of said capacitor and a corresponding firing of said unijunction transistor, and a transformer, one of whose windings is coupled to the base 1 electrode of said unijunction transistor and another of whose windings is coupled to said charging circuit, said one winding inducing current flow in said another winding each time said unijunction transistor fires.

20. A power supply circuIt as in claim 16 wherein said charging circuit comprises a transformer, one winding of which is coupled to said A.C. source, a full-wave bridge rectifier coupled by a first pair of diagonal nodes across the other winding of said transformer, one node of a second pair of diagonal nodes of the bridge rectifier being coupled to said D.C. source, and a silicon-controlled rectifier whose anode-cathode circuit couples the other node of said second pair of diagonal nodes to said D.C. source and whose gate electrode is coupled to said D.C. sensing circuit for receiving said charging control signal to thereby cause said silicon-controlled rectifier to assume a conducting condition.

21. A power supply circuit as in claim 2 further comprising a D.C. source shutdown circuit for preventing application of said control signal to said control circuit if the amplitude of the signal produced by said D.C. source falls below a predetermined level.

22. A power supply circuit as in claim 21 wherein said shutdown circuit comprises threshold detection means for producing an output signal if the signal produced by said D.C. source falls below a predetermined level, and means coupled to said A.C. sensing circuit and responsive to the output signal from the threshold detection means for conducting to ground any control signal produced by the sensing circuit.