About issues caused by electrical noise, or improving the Signal/Noise ratio of an analog circuit.

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1answer
26 views

In current mobile phones, what are some specific techniques that prevent handling noise (rubbing, jostling) from being picked up by the microphone?

I've noticed that when using my smartphone the vibrations from my actions aren't picked up, or are picked up very faintly by the microphone. I've worked quite a bit with microphones and I know it must ...
2
votes
3answers
110 views

Debugging when oscilloscope grounds cures the problem

In a nutshell : My circuit behaves erratically I connect the 'scope to find out why The problem disappears In particular, this concerns the circuit in my last question although this is not ...
6
votes
3answers
130 views

60Hz “click” or clipping noise when differential amplifier is surrounded by salt water

I am a graduate student attempting to take electrophysiology recordings from a lobster under water. In the current set up I am using, two differential amplifier boards are attached the the lobster's ...
0
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1answer
29 views

GSM module noise

I'm developing an embedded system that uses telit gl865 modem to connect to a server using gprs. I've noticed that the module makes a strange noise when connected. It's the same noise I used to hear ...
0
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1answer
38 views

Where and how do I put an inductor on a volume control

I built an stereo equalizer but I made some mistakes. As the potentiometers didn't fit on my PCB I had to put them separated and make the connections with some wires. The other mistake is that I made ...
-3
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1answer
34 views
0
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1answer
31 views

Low current more susceptible to noise?

Supose I have an opamp with pnp input stage (constant current flowing out the input pin), like the following: simulate this circuit – Schematic created using CircuitLab Would the input ...
17
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4answers
1k views

How to clean up a noisy signal?

I'm controlling a 4-pin PWM PC fan from a PIC16F684 with the fan speed driven from an ADC reading of a proximity sensor. This all works ok. I wasn't originally planning to use the tachometer output ...
1
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1answer
54 views

Am I getting DC bandwidth correctly?

I am computing Johnson and shot noise in a DC circuit, where I have an Arduino Due sampling with "delay(100);", i.e. at 10Hz. Sampling rate and bandwidth follow Nyquist sampling theorem. According ...
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0answers
38 views

Low-noise SPDT switch

I need to produce an extremely low noise SPDT switch. This switch will take two different inputs to a single 16 bit ADC. The inputs are 50 ohm BNC outputs from trans-impedance amplifiers. The ...
0
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1answer
72 views

misunderstanding from definition of SNR

We know that SNR is defined as "power" of the transmitted signal to the "power" of the noise. In practice we transmit time limited signals (for simplicity consider the case that there is only one ...
-1
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2answers
85 views

Concept of noise floor

Can anyone please explain the concept of noise floor. If we want to design an active high pass filter with a cut off frequency of 12 kHz and pass band gain of 2, how do we apply the concept of noise ...
0
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1answer
57 views

Motor noise interfering with I2C

I built a robot using the Arduino Due with all the sensors running at 5V over I2C. There is a level shifter on both I2C lines. The motors are controlled using a VNH5019 motor driver carrier from ...
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2answers
261 views

Noise caused by improper decoupling of VDD pin

I have posed a question, "Function run in MCU generate noise to the analog circuit", before but at that time the question was not detailed enough. After several days` of testing, the problem is now ...
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1answer
41 views

USB switching power supply filter

Good afternoon fellow students of life, I have a particular question that relates to the use of a Duracell USB switching power supply as the main supply for a high sensitivity sensor board. Most of ...
0
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0answers
25 views

What is a cheap way of isolating a large parallel plate capacitor from background fields

I am making liquid level detector that will rely on a change in capacitance to determine the changing heights of various solutions in a tube placed between two stainless steel plates(20cm x 12cm). I ...
0
votes
2answers
87 views

Function run in MCU generate noise to the analog circuit

As my circuit is a little complicated, I don`t know how to pose the PCB here. So I just want to know the probable causes of the problem and I will test them one by one later and report back. My ...
0
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0answers
32 views

Noise on a tda2003 circuit

I've built an amp using TDA2003. If I use a common 9V battery, it works nice, with very low noise. But, if I change to a power supply (that I borrowed from a cell phone charger) that delivers 8.4V ...
0
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1answer
62 views

Noisy sensor on a prototyping board

I made a small prototyping board where accelerometer data is read into a microprocessor, showing the data from the accelerometer after it is sampled, gives a very noisy signal. (50 mv peaks) I had a ...
2
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2answers
48 views

Removing spikes from multiple onboard power supplies

I have a board that is based around an STM32F303 and am using the onboard ADC/DAC, fed by a 3V power supply derived from a USB 5V input. The 5V also feeds a module, RD0515, which creates +/- 15V for ...
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0answers
40 views

Possible ways of protecting comparator input from coupling?

Overview So as I'm implementing some logic with a comparator, I've run into the problem of the output swing coupling with one of the inputs, and now I'm searching for possible ways to minimize or ...
6
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1answer
149 views

How serial resistors actually reduce EMI?

I am recently working with a GSM based system, and there was this advice in the datasheet of the GSM module: 22Ω resistors should be connected in series between the module and the SIM card so as ...
0
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2answers
52 views

Can a malfunctioning relay in an amp cause or allow a speaker to crackle when turning the vol potentiometer? [closed]

Ok, so this question has several layers, I admit it. I recently acquired a Lepai 2020A+ amp. It is, I believe, the latest version PCB because it has the two relays for speaker protection instead of ...
0
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1answer
65 views

Inverting Opamp on Noisy Ground. Would an LC filter help?

Alright, say I have this Inverting Opamp, but it so happens the positive input to ground is also connected with another sub-circuit that happens to produce a lot of noise (no pun intended): ...
0
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1answer
61 views

Stop earth from introducing noise to piezo circuit

I am currently prototyping a circuit which measures pulses on piezo-electric sensors; however, I seem to be having an issue with noise. When the circuit is battery powered (and therefore floating), ...
0
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0answers
66 views

Does anyone know why DC-DC converter have noise

I am running an issue that my custom board has noise come from DC-DC converter after running a while. I used V78W-500 as the DC-DC converter and already replaced a new one. Except noise, the voltage ...
2
votes
1answer
66 views

Sonar single transducer element SNR vs array SNR

Background: I'm taking a flexible learning unit on radar and sonar systems in a vocational college for an assoc. degree level course. The teacher has given us a reading assignment: "Chapter 15 ...
0
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1answer
125 views

Noise on TL074 / TL084 but not on LM324

I made a circuit that modifies a signal so it can be safely read by an ADC. I'm using an op amp to shift the signal +2.5V so I can measure AC. When I do this shift another signal appears. About 40mV ...
-1
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1answer
65 views

What does zero-mean noise mean? [closed]

I asked this question about zero-mean noise on Physics Stack Exchange and got this answer: Zero mean so that the noise does not present a net disturbance to the system. There's as much positive ...
3
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2answers
84 views

Does transformer humming cause notable waste of energy?

AFAIK transformers hum because alternating magnetic field causes pieces of laminated core to slightly deform and vibrate and that is simply a byprocess of how transformers work. However for the same ...
1
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1answer
55 views

ADC outputs random values to constant input

I am using ADC (ADS7822) from TI and I have some strange behaviour with it. Below diagram explains the voltage inputs and connections. I was reading strange values with this setup. I removed ...
2
votes
1answer
53 views

Ground Plane Noise?

I have some noise issues on a PCB that I am having a hard time troubleshooting. Below are pictures of the schematic as well as 2 scope traces. The first trace shows the amplified signal with the noise ...
1
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1answer
51 views

Tunnel diode I-V curve noise [closed]

Wikipedia gives this example of an I-V curve of a tunnel diode. What is the "noise" in the negative resistance region? Is it a characteristic of the diode or of the measuring circuit? The caption says ...
3
votes
1answer
140 views

Micro controller reset due to noise, PCB design for noise immunity

After making this PCB, I learnt the importance of ground plane. Besides ground plane, there is considerable amount of theory behind PCB designing which can provide immunity against ESD, surge, EMI, ...
0
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1answer
41 views

What current values are prone to noise?

I'm using voltage dividers to drop down from high voltages like 327V peak to 2.5V peak and read it with an ADC. (Also reading lower voltages like 5V from various sources, so the above was just an ...
0
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1answer
116 views

Reducing signal noise arduino to simulink analog read

I'm using an op amp to amplify the input of a pressure sensor from milli volt to volts using with arduino. Both the amp and the sensor are externally powered using a DC power supply. I'm trying to ...
0
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0answers
72 views

Generating very low noise control voltage from an MCU?

I want to control the THAT Corp. 2180 VCA using an MCU. I'm using the positive VC input (it has one positive and one negative and they are symmetrical). The range that I want to generate is +/-540mV. ...
0
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0answers
72 views

ADS1278 Noise level

I have been using ADS1278 TI ADC, after I made the digital side work with my processor, I shorted the + and - of the analog input for a channel to check the noise (used recommended capacitors for ...
0
votes
1answer
74 views

Fixing a noisy I2C bus

I'm trying to get an I2C bus working but there's a ton of noise and I don't really know what's causing it. The circuit is pretty simple, an ITG-3200 and an Arduino DUE. Here is the problem: As you ...
1
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1answer
107 views

Low Noise Using Opamp And Photodiode?

I'm building a small sensor setup that is able to measure the transmission of light through a (clouded) solution. I currently have a laser light that shines through the solution and a LDR on the ...
4
votes
2answers
165 views

Circuit Implementation of Dynamical Systems - Lorenz Equations (Failure Analysis)

Let me begin with the disclaimer: I am a mathematician and not an electrical engineer. That being said, surely I am missing something simple. For classroom demonstrations in dynamical systems, I have ...
0
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0answers
54 views

Inverter noise picked up on USB data lines breaks USB communication - signal integrity

I have an equipment where the CPU is a 16-bit dsPIC. There is an inverter board switching 300V across a 4 MOSFETS H-bridge at 20kHz and delivering 180W. This equipment communicates with a computer ...
0
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0answers
35 views

Reducing noise from an input using an FIR in VHDL

I have a non digital input I want to read in my VHDL file but it has sooo much noise that I would like to filter out using a digital filter that would sample the signal and allow pulse levels that ...
0
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0answers
22 views

RIN measurement of CW laser

Right now Im doing an RIN measurement of a CW Raman fiber laser. In theory, Im supposed to see a relaxation oscillation which manifests as a single peak in the trace. What if I can't detect the ...
0
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0answers
43 views

How much the noise of this circuit?

I have a circuit like this. From the data sheet of the Op Amp I know that it has voltage noise $$e_n=0.85\frac{\text{nV}}{\sqrt{\text{Hz}}}$$ and electric noise ...
1
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2answers
67 views

Placing electricity, cable, phone and internet transmission lines tight together

Will this cause noise in the phone and internet signal? also placing them through concrete with absolutely no air space around them. This is happening in one of my friends house, he has issues with ...
0
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2answers
89 views

Electronic compass, RF and batteries

I am currently working with a project where i am creating a small embedded board consisting of a 9DoF IMU which is transmitting its data with RF (BLE or normal RF). Furthermore there will be a battery ...
0
votes
1answer
52 views

What is the best practice to measure 3 phase grid voltage using a dsp chip for synchronization?

I want to measure the current grid voltage to synchronize a dc power supply with the grid using an inverter. Now I'm particularly interested in finding noise and harmonic information about the grid ...
0
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0answers
47 views

Odd red noise appears on the display of my Samsung SyncMaster 943N monitor [closed]

I have a problem with my Samsung SyncMaster 943N monitor. For some reason red noise appears on the displayed screen. Notice the red noise around the white zones in the image: Tried connecting it ...
0
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0answers
34 views

Waterfall diagram for car starting coil signal/interference

Does anyone have a waterfall diagram for the signal given off by an ignition coil when a car starts (or is operating)?