# Patent

## Title
Polyphase source detecting circuit

## Abstract

A polyphase source detecting circuit configured for detecting a polyphase source having three sources includes three sampling circuits and an alarm circuit. Each sampling circuit has a control switch. A control terminal of the control switch of each sampling circuit is connected to one of the phase sources of the polyphase source respectively. The alarm circuit has a first transistor, a first LED, and a buzzer. The anode of the first LED is connected to a power supply. The cathode of the first LED is connected to the base of the first transistor and connected to ground via the control switches of the sampling circuits in turn. The collector of the first transistor is connected to the power supply via the buzzer. The emitter of the first transistor grounded.

## Background
BACKGROUND
1. Field of the Invention
The present invention relates to detecting circuits, and particularly to a polyphase source detecting circuit which can detect each phase source of a polyphase source.
2. Description of Related Art
Nowadays, polyphase sources such as three-phase sources are widely used in power supply systems of many electronic products. When a polyphase source used for an electronic product works, a detecting circuit needs to be used to detect work status of the polyphase source. However, if one phase source of the polyphase source does not work, the conventional detecting circuit cannot detect the phase source that isn't working, the polyphase source will continue to work, thereby increasing the load to the remaining phase sources, which may damage the polyphase source.
What is needed is to provide a polyphase source detecting circuit which can detect each phase source of a polyphase source.
SUMMARY
A polyphase source detecting circuit configured to detect a polyphase source having three phase sources, includes three sampling circuits and an alarm circuit. The three sampling circuits each has a control switch, a control terminal of the control switch of each of the three sampling circuits is connected to one of the three phase sources of the polyphase source respectively. The alarm circuit has a first transistor, a buzzer, a first light-emitting diode (LED), a first diode, and a second diode, the anode of the first LED is connected to a power supply, the cathode of the first LED is connected to the cathode of the first diode, the anode of the first diode is connected to the anode of the second diode and the power supply via a first resistor, the cathode of the second diode is connected to the base of the first transistor, the collector of the first transistor is connected to the power supply via the buzzer, the emitter of the first transistor is connected to ground, the cathode of the first LED is connected to ground via the control switches of the three sampling circuits in turn, if one of the three phase sources is not working, the corresponding control switch is turned off, thereby the first LED is turned off and the buzzer is turned on.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of an embodiment when taken in conjunction with the accompanying drawing, in which:



BRIEF DESCRIPTION OF THE DRAWING
The drawing is a circuit diagram of a polyphase source detecting circuit in accordance with an embodiment of the present invention.



DETAILED DESCRIPTION
Referring to the drawing, a polyphase source detecting circuit in accordance with an embodiment of the present invention includes a first sampling circuit 1, a second sampling circuit 2, a third sampling circuit 3, and an alarm circuit 400. In this embodiment, the polyphase source detecting circuit is configured for detecting a three-phase source. The first sampling circuit 1, the second sampling circuit 2, and the third sampling circuit 3 are configured to detect a first phase source A, a second phase source B, and a third phase source C respectively. In other embodiments, other kinds of polyphase sources can be detected by increasing or reducing the number of corresponding sampling circuits.
The first sampling circuit 1 includes a diode D1, an integral circuit 100 having a resistor R1 and a capacitor C1, a bleeder circuit 200 having a resistor R2 and a resistor R3, an indicator circuit 300 having a resistor R12 and a light-emitting diode (LED) D4, and a control switch such as an NMOS transistor Q2. The anode of the diode D1 is connected to the power output of the first phase source A. The cathode of the diode D1 is connected to the gate of the transistor Q2 via the resistors R1 and R2 in turn. One terminal of the capacitor C1 is connected to a node between the resistor R1 and the resistor R2. The other terminal of the capacitor C1 is grounded. The gate of the transistor Q1 is connected to the anode of the LED D4 via the resistor R12, and connected to ground via the resistor R3. The cathode of the LED D4 is grounded.
The second sampling circuit 2 includes a diode D2, an integral circuit 110 having a resistor R4 and a capacitor C2, a bleeder circuit 210 having a resistor R5 and a resistor R6, an indicator circuit 310 having a resistor R13 and a LED D5, and a control switch such as an NMOS transistor Q3. The anode of the diode D2 is connected to the power output of the second phase source B. The cathode of the diode D2 is connected to the gate of the transistor Q3 via the resistors R4 and R5 in turn. One terminal of the capacitor C2 is connected to a node between the resistor R4 and the resistor R5. The other terminal of the capacitor C2 is grounded. The gate of the transistor Q3 is connected to the anode of the LED D5 via the resistor R13, and connected to ground via the resistor R6. The cathode of the LED D5 is grounded.
The third sampling circuit 3 includes a diode D3, an integral circuit 120 having a resistor R7 and a capacitor C3, a bleeder circuit 220 having a resistor R8 and a resistor R9, an indicator circuit 320 having a resistor R14 and a light-emitting diode (LED) D6, and a control switch such as an NMOS transistor Q4. The anode of the diode D3 is connected to the power output of the third phase source C. The cathode of the diode D3 is connected to the gate of the transistor Q4 via the resistors R7 and R8 in turn. One terminal of the capacitor C3 is connected to a node between the resistor R7 and the resistor R8. The other terminal of the capacitor C3 is grounded. The gate of the transistor Q4 is connected to the anode of the LED D6 via the resistor R14, and connected to ground via the resistor R9. The cathode of the LED D6 is grounded.
The source of the transistor Q2 is connected to the drain of the transistor Q3. The source of the transistor Q3 is connected to the drain of the transistor Q4. The source of the transistor Q4 is grounded. The diodes D1, D2, and D3 are respectively configured to prevent power from the capacitors C1, C2, and C3 damaging the phase sources A, B, and C.
The alarm circuit 400 includes a NPN transistor Q1, a buzzer LS1, resistors R10, R11, R22, diodes D8, D9, and a LED D7. The base of the transistor Q1 is connected to the cathode of the diode D8, the anode of the diode D8 is connected to a power supply Vcc via the resistor R11, and also connected to the anode of the diode D9. The cathode of the diode D9 is connected to the drain of the transistor Q2, the cathode of the diode D9 is connected to the cathode of the LED D7, the anode of the LED D7 is connected to the power supply Vcc via the resistor R10. The collector of the transistor Q1 is connected to the power supply Vcc via the buzzer LS1 and the resistor R22, and the emitter of the transistor Q1 is grounded.
In use, if the three phase sources A, B, and C are all working normally, the LEDs D4, D5, and D6 are all turned on to respectively show the three phase sources A, B, and C are good. At the same time, the transistors Q2, Q3, and Q4 are turned on, and then the LED D7 is turned on, the transistor Q1 is turned off, and the buzzer LS1 is off all of which indicates the three-phase source is good.
If one of the three phase sources A, B, and C such as the first phase source A stops working, but the two phase sources B, and C are both working normally, the LED D4 is turned off to show the first phase sources A is bad and the LEDs D5 and D6 are on to respectively show the two phase sources B and C are good. At the same time, the transistor Q2 and the LED D7 are turned off and the transistor Q1 is turned on. Thereby the buzzer LS1 works to indicate the three-phase source is bad.
In other embodiments, the colors of the LEDs D4, D5, D6, and D7, can be changed according to need. The polyphase source detecting circuit can accurately detect each phase source of a polyphase source.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

## Claims

1. A polyphase source detecting circuit configured to detecting a polyphase source having three phase sources, comprising:
three sampling circuits each having a control switch, a control terminal of the control switch of each of the three sampling circuits connected to one of the three phase sources of the polyphase source respectively; and
an alarm circuit having a first transistor, a buzzer, a first light-emitting diode (LED), a first diode, and a second diode, the anode of the first LED connected to a power supply, the cathode of the first LED connected to the cathode of the first diode, the anode of the first diode connected to the anode of the second diode and the power supply via a first resistor, the cathode of the second diode connected to the base of the first transistor, the collector of the first transistor connected to the power supply via the buzzer, the emitter of the first transistor connected to ground, the cathode of the first LED connected to ground via the control switches of the three sampling circuits in turn, if one of the three phase sources ceases working, the corresponding control switch is turned off, thereby the first LED is turned off and the buzzer is turned on.

2. The polyphase source detecting circuit as claimed in claim 1, wherein the first transistor is an NPN transistor.

3. The polyphase source detecting circuit as claimed in claim 1, wherein each of the three sampling circuit further comprises a third diode, an integral circuit having a second resistor and a first capacitor, a bleeder circuit having a third resistor and a fourth resistor, and an indicator circuit having a fifth resistor and a second LED, the corresponding control switch is an NMOS transistor, the anode of the third diode is connected to the corresponding phase source, the cathode of the third diode is connected to the gate of the corresponding control switch via the second and third resistors in turn, one terminal of the first capacitor is connected to a node between the second and third resistors, the other terminal of the first capacitor is grounded, the gate of the corresponding control switch is connected to the anode of the second LED via the fifth resistor, and connected to ground via the fourth resistor, the cathode of the second LED is grounded.