CN204514996U - Alternating current testing circuit - Google Patents
Alternating current testing circuit Download PDFInfo
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- CN204514996U CN204514996U CN201520154787.7U CN201520154787U CN204514996U CN 204514996 U CN204514996 U CN 204514996U CN 201520154787 U CN201520154787 U CN 201520154787U CN 204514996 U CN204514996 U CN 204514996U
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Abstract
The utility model relates to alternating current detection technique field, be specifically related to a kind of alternating current testing circuit, the negative terminal one tunnel first resistance R1 of the first operational amplifier U1A holds with the input signal AC-N of alternating current and is connected, another Lu Jing tri-resistance R3 is connected with the output terminal of the first operational amplifier U1A, anode one tunnel second resistance R2 holds with the input signal AC-L of alternating current and is connected, and another Lu Yu tetra-resistance R4 meets GND after connecting; Output terminal one tunnel of the first operational amplifier U1A is connected with the anode of the second operational amplifier U1B after the 5th resistance R5, connects reference voltage after another Lu Jing six resistance R6; The negative terminal of the second operational amplifier U1B is connected with output terminal; Output terminal road after the 7th resistance R7 of the second operational amplifier U1B connects output 3 pin of switching diode D1, another road output waveform.The utility model can detect little AC signal, and testing result is accurate, not influenced by ambient temperature.
Description
Technical field
The utility model relates to alternating current detection technique field, particularly relates to alternating current testing circuit.
Background technology
In modern UPS, EPS power-supply system, all need to use alternating current input, and alternating current is detected, the large voltage signal of interchange is processed into small voltage direct current signal send DSP analog quantity sample port to judge for DSP, and send fill order, therefore most important to the steady operation of accuracy to power-supply system of alternating current detection.Common detection means is, utilize diode rectification, capacitor filtering, DSP is sent again through being suitably processed into small voltage direct current signal, there is shortcomings in this circuit: 1, diode exists threshold voltage, when the alternating current voltage detected is less than threshold voltage, diode rectifier circuit cisco unity malfunction, now cannot detect alternating current; 2, there is nonlinearity erron in diode, and detection can be caused inaccurate; 3, the temperature characterisitic of diode is poor, easily influenced by ambient temperature, and detection can be caused inaccurate.
Summary of the invention
For solving the problem, the utility model provides a kind of alternating current testing circuit, and it can detect little AC signal, and testing result is accurate, not influenced by ambient temperature.
The utility model adopts following technical scheme: a kind of alternating current testing circuit, it comprises the first operational amplifier U1A, the second operational amplifier U1B and switching diode D1, the negative terminal one tunnel first resistance R1 of described first operational amplifier U1A holds with the input signal AC-N of alternating current and is connected, another Lu Jing tri-resistance R3 is connected with the output terminal of the first operational amplifier U1A, the anode one tunnel second resistance R2 of the first operational amplifier U1A holds with the input signal AC-L of alternating current and is connected, another Lu Yu tetra-resistance R4 meets GND after connecting, and forms differential amplifier; Output terminal one tunnel of described first operational amplifier U1A is connected with the anode of the second operational amplifier U1B after the 5th resistance R5, connects reference voltage, as the direct current biasing of rear class follower after another Lu Jing six resistance R6; The negative terminal of described second operational amplifier U1B is connected with output terminal, forms follower; Output terminal road after the 7th resistance R7 of described second operational amplifier U1B connects output 3 pin of switching diode D1, another road output waveform, the positive termination GND end of described switching diode D1, negative termination power.
Being improved to further technique scheme, described alternating current testing circuit also comprises electric capacity C1, and one end is connected with the output terminal of the 7th resistance R7, and another termination GND holds.
Preferably, described first resistance R1 resistance is identical with the second resistance R2 resistance.
Preferably, described 3rd resistance R3 resistance is identical with the 4th resistance R4 resistance.
Alternating current testing circuit described in the utility model, beneficial effect is compared to existing technology:
This circuit does not use diode, also just there is not threshold voltage, and there is not nonlinearity erron, therefore can detect little AC signal, and testing result is accurate; Do not use diode, circuit also can not by the impact of temperature, and testing result is accurate.
Accompanying drawing explanation
Fig. 1 is the structural representation of the utility model embodiment alternating current testing circuit;
Fig. 2 is the output voltage Uo1 oscillogram of the utility model embodiment alternating current testing circuit first operational amplifier U1A;
Fig. 3 is the input voltage Uo2 oscillogram of the utility model embodiment alternating current testing circuit second operational amplifier U1B;
Fig. 4 is the output voltage Uo oscillogram of the utility model embodiment alternating current testing circuit.
Embodiment
Below in conjunction with accompanying drawing, the utility model is further described.
Embodiment:
With reference to Fig. 1, alternating current testing circuit described in the utility model, it comprises the first operational amplifier U1A, second operational amplifier U1B, switching diode D1, first resistance R1, second resistance R2, 3rd resistance R3, 4th resistance R4, 5th resistance R5, 6th resistance R6 and the 7th resistance R7, wherein, negative terminal i.e. 9 pin one tunnels of the first operational amplifier U1A are connected with one end of the 3rd resistance R3, the other end of the 3rd resistance R3 is connected with output terminal i.e. 8 pin of the first operational amplifier U1A, another road is connected with one end of the first resistance R1, the other end of the first resistance R1 is held with the input signal AC-N of alternating current and is connected, anode one tunnel of the first operational amplifier U1A is connected with the input end of the second resistance R2, the output terminal of the second resistance R2 is held with the input signal AC-L of alternating current and is connected, one end of another Lu Yu tetra-resistance R4 connects, another termination GND of 4th resistance R4,8,9,10 pin of resistance R1, R2, R3, R4 and the first operational amplifier U1A form differential amplifier, for zooming in or out input signal.The output voltage of the first operational amplifier U1A is Uo1, and the first resistance R1 is equal with the resistance of the second resistance R2, and the 3rd resistance R3 is equal with the resistance of the 4th resistance R4, and the first operational amplifier U1A, the second operational amplifier U1B adopt TL074.
Output terminal i.e. 8 pin of the first operational amplifier U1A are connected with the 5th resistance R5 one end, the 5th resistance R5 other end one tunnel is connected with anode i.e. 12 pin of the second operational amplifier U1B, one end of another Lu Yu six resistance R6 connects, another termination reference voltage of 6th resistance R6, form the direct current biasing of rear class follower, for raising input exchange signal.In the present embodiment, this reference voltage is+3V, and the 5th resistance R5 output voltage is Uo2.
Negative pole i.e. 13 pin of the second operational amplifier U1B are communicated with its output terminal i.e. 14 pin, and 4 pin of the second operational amplifier U1B connect+15V voltage, and 11 pin connect-15V voltage, and 12,13,14 pin of the second operational amplifier U1B form follower.
Output terminal i.e. 14 pin of the second operational amplifier U1B are connected with one end of the 7th resistance R7, the other end one road output voltage Uo of the 7th resistance R7, and another road connects GND end after electric capacity C1.Anode i.e. 1 pin of switching diode D1 connects GND end, and negative terminal i.e. 2 pin connect+3V power supply, and 3 pin of switching diode D1 are connected with output terminal i.e. 14 pin of the second operational amplifier U1B.The present embodiment breaker in middle diode D1 is BAT
54S.
The principle of work of this circuit is:
U1 is input AC-N terminal voltage, U2 is input AC-L terminal voltage, in an input AC electricity sinusoidal cycles, sampling end input AC electricity is via R1, R2, R3, 8 of R4 and amplifier U1A, 9, the differential amplifier that 10 pin are formed, scale up and obtain output voltage Uo1, output voltage Uo1=R3/R1 (U2-U1) is known by differential amplifier computing formula, namely when sampled signal is one-period positive half-wave, due to U2-U1 > 0, therefore amplifier U1A exports Uo1 is alternating current positive half-wave waveform, when sampled signal be one-period bear half-wave time, due to U2-U1 < 0, therefore amplifier U1A exports Uo1 is negative half waveform of alternating current, Uo1 waveform is exported as shown in Figure 2 in input AC electricity complete cycle.
Uo1 gives 12 pin of amplifier U1B again through resistance R5, and superposes with positive 3V reference voltage at 12 pin, and producing voltage U o2, Uo2 is still sinusoidal waveform change, but minimum voltage higher than 0V, Uo2 waveform as shown in Figure 3.
Uo2 via the follower isolation and amplifier of 12,13, the 14 pin formations of amplifier U1B, then send DSP through switching diode D1 amplitude limit output Uo signal, can determine the situation of input AC electricity.Output waveform Uo as shown in Figure 4.Thus, the detection to input AC electricity is completed.
The above embodiment only have expressed several embodiment of the present utility model, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the utility model the scope of the claims.It should be pointed out that for the person of ordinary skill of the art, without departing from the concept of the premise utility, can also make some distortion and improvement, these all belong to protection domain of the present utility model.Therefore, the protection domain of the utility model patent should be as the criterion with claims.
Claims (4)
1. an alternating current testing circuit, it is characterized in that: comprise the first operational amplifier U1A, the second operational amplifier U1B and switching diode D1, the negative terminal one tunnel first resistance R1 of described first operational amplifier U1A holds with the input signal AC-N of alternating current and is connected, another Lu Jing tri-resistance R3 is connected with the output terminal of the first operational amplifier U1A, the anode one tunnel second resistance R2 of the first operational amplifier U1A holds with the input signal AC-L of alternating current and is connected, another Lu Yu tetra-resistance R4 meets GND after connecting, and forms differential amplifier; Output terminal one tunnel of described first operational amplifier U1A is connected with the anode of the second operational amplifier U1B after the 5th resistance R5, connects reference voltage, as the direct current biasing of rear class follower after another Lu Jing six resistance R6; The negative terminal of described second operational amplifier U1B is connected with output terminal, forms follower; Output terminal road after the 7th resistance R7 of described second operational amplifier U1B connects output 3 pin of switching diode D1, another road output waveform, the positive termination GND end of described switching diode D1, negative termination power.
2. alternating current testing circuit according to claim 1, it is characterized in that: also comprise electric capacity C1, one end is connected with the output terminal of the 7th resistance R7, and another termination GND holds.
3. alternating current testing circuit according to claim 1, is characterized in that: described first resistance R1 resistance is identical with the second resistance R2 resistance.
4. alternating current testing circuit according to claim 1, is characterized in that: described 3rd resistance R3 resistance is identical with the 4th resistance R4 resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520154787.7U CN204514996U (en) | 2015-03-18 | 2015-03-18 | Alternating current testing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520154787.7U CN204514996U (en) | 2015-03-18 | 2015-03-18 | Alternating current testing circuit |
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| Publication Number | Publication Date |
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| CN204514996U true CN204514996U (en) | 2015-07-29 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201520154787.7U Active CN204514996U (en) | 2015-03-18 | 2015-03-18 | Alternating current testing circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107462765A (en) * | 2017-09-07 | 2017-12-12 | 昆山龙腾光电有限公司 | A kind of signal deteching circuit and device |
| CN108254615A (en) * | 2018-01-30 | 2018-07-06 | 上海乐田教育科技有限公司 | A kind of Current Mutual Inductance circuit for teaching programming plate |
-
2015
- 2015-03-18 CN CN201520154787.7U patent/CN204514996U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107462765A (en) * | 2017-09-07 | 2017-12-12 | 昆山龙腾光电有限公司 | A kind of signal deteching circuit and device |
| CN108254615A (en) * | 2018-01-30 | 2018-07-06 | 上海乐田教育科技有限公司 | A kind of Current Mutual Inductance circuit for teaching programming plate |
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