An alternating voltage presence detection circuit

Abstract

This utility model discloses an AC voltage presence detection circuit, relating to the field of AC voltage detection technology. It includes resistors R1 and R2, a diode D1, an optocoupler, and resistor R3. The first ends of resistors R1 and R2 are respectively connected to one input terminal of the AC power supply. The second ends of resistors R1 and R2 are respectively connected to the two ends of diode D1 and the two pins of the primary winding of the optocoupler. One pin of the secondary winding of the optocoupler is grounded, and the other pin serves as the detection signal output terminal and is connected to the power supply through resistor R3. This utility model has a simple circuit and can be implemented using a common optocoupler, offering advantages such as reduced cost, fewer components, and simplified circuitry.

Description

Technical Field

[0001] This utility model relates to the field of AC voltage detection technology, specifically, to an AC voltage presence detection circuit. Background Technology

[0002] There are currently three main methods for detecting the presence of AC voltage: 1) Detecting AC voltage using a voltage transformer as the main component; this method requires a large transformer, occupies a lot of circuit board space, and has low cost-effectiveness; 2) Detecting AC voltage using capacitors and AC optocouplers as the main components; this method has high requirements for both optocouplers and capacitors, and has low cost-effectiveness; 3) Detecting AC voltage using a circuit mainly composed of sampling resistors and AD conversion circuits; this method uses many components, has a complex circuit design, occupies a lot of circuit board space, and is not conducive to the stable operation of the circuit board. Utility Model Content

[0003] The purpose of this invention is to provide an AC voltage presence detection circuit to solve the problems of large circuit board space occupation and low cost-effectiveness of existing AC voltage presence detection methods.

[0004] The present invention solves the above problems through the following technical solution:

[0005] An AC voltage presence detection circuit includes resistors R1 and R2, diode D1, optocoupler, and resistor R3. The first ends of resistors R1 and R2 are respectively connected to one input terminal of AC power. The second ends of resistors R1 and R2 are respectively connected to the two ends of diode D1 and the two pins of the primary winding of optocoupler. One pin of the secondary winding of optocoupler is grounded, and the other pin serves as the detection signal output terminal and is connected to the power supply through resistor R3.

[0006] Furthermore, the diode D1 is a rectifier diode.

[0007] Furthermore, the resistors R1 and R2 are current-limiting resistors.

[0008] Furthermore, the resistor R3 is a pull-up resistor.

[0009] Furthermore, the first end of resistor R1 is connected to the AC input terminal L, the second end of resistor R1 is connected to the negative terminal of diode D1 and pin 1 of the optocoupler, the first end of resistor R2 is connected to the AC input terminal N, the second end of resistor R2 is connected to the positive terminal of diode D1 and pin 2 of the optocoupler, pin 3 of the optocoupler is grounded, and pin 4 of the optocoupler serves as the detection signal output terminal and is connected to the power supply through resistor R3.

[0010] Furthermore, the optocoupler is model PC817.

[0011] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0012] This invention features a simple circuit that can be implemented using a common optocoupler, offering advantages such as reduced cost, fewer components, and simplified circuitry. Attached Figure Description

[0013] Figure 1 This is the circuit schematic diagram of this utility model;

[0014] Figure 2 This is a waveform diagram of the detection of this utility model;

[0015] Among them, U1 is an optocoupler. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0017] Example:

[0018] Combined with appendix Figure 1 As shown, an AC voltage presence detection circuit includes resistors R1 and R2, diode D1, optocoupler U1, and resistor R3. The first ends of resistors R1 and R2 are respectively connected to one input terminal of AC power. The second ends of resistors R1 and R2 are respectively connected to the two ends of diode D1 and the two pins of the primary winding of optocoupler U1. One pin of the secondary winding of optocoupler U1 is grounded, and the other pin serves as the detection signal output terminal and is connected to the power supply through resistor R3.

[0019] Furthermore, the diode D1 is a rectifier diode.

[0020] Furthermore, the resistors R1 and R2 are current-limiting resistors.

[0021] Furthermore, the resistor R3 is a pull-up resistor.

[0022] Furthermore, the first end of resistor R1 is connected to the AC input terminal L, the second end of resistor R1 is connected to the negative terminal of diode D1 and pin 1 of optocoupler U1, the first end of resistor R2 is connected to the AC input terminal N, the second end of resistor R2 is connected to the positive terminal of diode D1 and pin 2 of optocoupler U1, pin 3 of optocoupler U1 is grounded, and pin 4 of optocoupler U1 serves as the detection signal output terminal and is connected to the power supply through resistor R3.

[0023] Furthermore, the optocoupler U1 is model PC817.

[0024] When AC mains power is available, there is a 220VAC voltage between AC input terminals L and N, causing optocoupler U1 to conduct at a frequency of 50Hz. During the positive half-cycle, the 220VAC voltage, after passing through current-limiting resistors R1 and R2, turns on optocoupler U1, pulling pin 4 of the secondary winding of optocoupler U1 low to ground, and the detection signal VD is low. During the negative half-cycle, the 220VAC voltage forms a loop through diode D1, preventing optocoupler U1 from conducting, and pulling pin 4 of the secondary winding of optocoupler U1 high to VCC, resulting in a high detection signal VD. This indicates the detection of a square wave signal with a 50% duty cycle, as shown in the waveform below. Figure 2 As shown.

[0025] When there is no mains power, there is no 220VAC voltage between AC input terminal L and AC input terminal N. Pin 4 of the secondary side of optocoupler U1 will be pulled high to VCC, and the detection signal VD will remain high.

[0026] Therefore, based on the detection signal VD, the presence or absence of AC voltage can be detected, that is, the existence detection of AC voltage.

[0027] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. A circuit for detecting the presence of AC voltage, characterized in that, The device includes resistors R1 and R2, diode D1, optocoupler, and resistor R3. The first ends of resistors R1 and R2 are respectively connected to one input terminal of AC power. The second ends of resistors R1 and R2 are respectively connected to the two ends of diode D1 and the two pins of the primary winding of optocoupler. One pin of the secondary winding of optocoupler is grounded, and the other pin serves as the detection signal output terminal and is connected to the power supply through resistor R3.

2. The AC voltage presence detection circuit according to claim 1, characterized in that, The diode D1 is a rectifier diode.

3. The AC voltage presence detection circuit according to claim 1, characterized in that, The resistors R1 and R2 are current-limiting resistors.

4. The AC voltage presence detection circuit according to claim 1, characterized in that, The resistor R3 is a pull-up resistor.

5. The AC voltage presence detection circuit according to claim 1, characterized in that, The first end of resistor R1 is connected to the AC input terminal L, the second end of resistor R1 is connected to the negative terminal of diode D1 and pin 1 of the optocoupler, the first end of resistor R2 is connected to the AC input terminal N, the second end of resistor R2 is connected to the positive terminal of diode D1 and pin 2 of the optocoupler, pin 3 of the optocoupler is grounded, and pin 4 of the optocoupler serves as the detection signal output terminal and is connected to the power supply through resistor R3.

6. The AC voltage presence detection circuit according to claim 5, characterized in that, The optocoupler is model PC817.

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