220 v alternating current collection and serious interference problem-CodePudding

220 v alternating current data normally normal and stable, but when the phone call, there will be a serious interference problem,
Friends help please analyse a reason bai, be obliged! ~

CodePudding user response:

Have you this thing without metal outside shell, noise correlation test, can't bare plate

CodePudding user response:

reference 1st floor Ruby0819 response:

you this thing without metal outside shell, noise correlation test, can't bare plate

Thank you, also plastic casing, should how to test and improve?

CodePudding user response:

Sampling differential line of high frequency filter, high frequency choke coil, copper and so on can effectively suppress the high frequency interference,

CodePudding user response:

Upstairs said would say,
Try the stick plastic shell inside a layer of metal film, grounding,
Look at the effect, make sure the interference sources,
If there is improvement, does not meet the requirements, also consider the improvement of external wiring harness, according to the following and improve circuit substrate,

The ultimate goal, without shielding case,

1. Improved grounding (Must)
2. PCB cloth plate
1. The area is small, as far as possible
2. The high impedance signal line on both sides and shielding
3. More than two layer printed circuit board, signal walk the middle layer, the lower level plus shielding
3. Circuit
The power, to the decoupled capacitance between the should have level (Pf),

CodePudding user response:

1. Look for the reasons, and then improve, targeted,
Added on hand can think of to improve the method first, try, is not easy, short time is hard to realize, put it back,

2. About the shielding case, get a iron shell button on the circuit board,
Remember, remember, remember, strengthen the grounding, shielding shell
3. If you want to EMC, only do this enough,

CodePudding user response:

Agree with upstairs point
Try the stick plastic shell inside a layer of metal film, grounding,
Look at the effect, make sure the interference sources,
If there is improvement, does not meet the requirements, also consider the improvement of external wiring harness, according to the following and improve circuit substrate,
The ultimate goal, without shielding case,
1. Improved grounding (Must)
2. PCB cloth plate
1. The area is small, as far as possible
2. The high impedance signal line on both sides and shielding
3. More than two layer printed circuit board, signal walk the middle layer, the lower level plus shielding
3. Circuit
The power, to the decoupled capacitance between the should have level (Pf),
4, if is to EMC, it is no good really, suggest looking for certification project to improve for you

CodePudding user response:

reference 4 floor Ruby0819 response:

upstairs said would say,
Try the stick plastic shell inside a layer of metal film, grounding,
Look at the effect, make sure the interference sources,
If there is improvement, does not meet the requirements, also consider the improvement of external wiring harness, according to the following and improve circuit substrate,

The ultimate goal, without shielding case,

1. Improved grounding (Must)
2. PCB cloth plate
1. The area is small, as far as possible
2. The high impedance signal line on both sides and shielding
3. More than two layer printed circuit board, signal walk the middle layer, the lower level plus shielding
3. Circuit
The power, to the decoupled capacitance between the should have level (Pf),

Thank you for your reply, there are the following questions:
1, strengthen the ground, you mean the earth, or circuit board GND
2, the area of the cloth of PCB board as far as possible little what meaning be? Is loop area and PCB size?
3, about the principle diagram not in need of improvement?

CodePudding user response:

1. Main is power, if your products meet the earth, you knot,
2. About the PCB area is small,
This refers to the power supply circuit (electric current flows through the closed loop) in the area of PCB board.
The area is small, radiation is small,
Part 3. About the circuit, you didn't draw,
From 220, filtering, sampling, 3 v power supply is what (battery, or what), saw the

Add, interference is the op-amp is, or is broken after class, before class is big, according to reason, to improve again,

CodePudding user response:

About 2, not only refers to the power supply, all the signals in the composition of current closed loop path, formed by the area

CodePudding user response:

Look for the reason, level 1 level check,

CodePudding user response:

references 9 f Ruby0819 response:

1. The main is power, if your products meet the earth, you knot,
2. About the PCB area is small,
This refers to the power supply circuit (electric current flows through the closed loop) in the area of PCB board.
The area is small, radiation is small,
Part 3. About the circuit, you didn't draw,
From 220, filtering, sampling, 3 v power supply is what (battery, or what), saw the

Add, interference is the op-amp is, or is broken after class, before class is big, according to reason, to improve again,

Thank you for your patience help!
Because I now just in this part of the measurement circuit, the separate principle diagram of the PCB,
The chip power is directly with dc power supply output is 3.3 V, the chip for LMV324IPWR,
The front is a three-phase multi-function meter output 5 v current directly, through an external 1000 change than transformer, connected to the board on the acquisition,
1, Rs is the sampling resistor, still need to filter? If you need to filter can solve the problem of signal interference?
2, I now test the Rs and R1 to connect test points have interference, because the point is not amplified, so there was no interference of the back of the big, can show what problem?
3, now just want to solve the problem of mobile phone signal interference, the preliminary idea is in the circuit to improve this, please grant instruction!!!!!

CodePudding user response:

1. All the twisted-pair cables recommended way tangle on
2. About the noise levels before and after, according to the magnification count
3. The first iron shell buckle try
Send a photos look at test environment, including the circuit board

CodePudding user response:

reference 13 floor Ruby0819 reply:

1. All the twisted-pair cables recommended way tangle on
2. About the noise levels before and after, according to the magnification count
3. The first iron shell buckle try
Send a photos look at test environment, including the circuit board

Thank you for your advice, I test today,

CodePudding user response:

Cell phone signal is 200 hz? (see lz oscillogram)

CodePudding user response:

That is not a mobile phone signal carrier,
Estimation is signal delivery cycle

CodePudding user response:

Wiring not exquisite, magnification is more than 10!