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

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-4
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1answer
62 views

Microcontroller freezes on high loads [on hold]

simulate this circuit – Schematic created using CircuitLab First timer on the forum and I'm asking for your help. Background: I've build a car with the exact same setup and it worked ...
0
votes
1answer
61 views

100Hz noise from a mains transformer

I bought a new speaker and it hums even with volume knob turned to 0. After opening it up, I noticed it was the iron transformer oscillating (and screwing it tighter does reduce the noise). How is ...
0
votes
1answer
53 views

Noise in DC causing unwanted LC resonance

I have a circuit like this: The part on the left generates AC signal. The part on the right detects whether AC is running through the branch when S1 is closed. I use a resonating LC circuit which ...
0
votes
3answers
79 views

Why does this circuit produce a static noise?

I was just designing this Common emitter transistor amplifier this morning. simulate this circuit – Schematic created using CircuitLab I have removed the input in the circuit ...
0
votes
2answers
50 views

Measuring Boltzmann constant using thermal noise

For my physics lab I have to come up with a way to measure Boltzmann constant using thermal noise. The circuit that I 'm going to use is something like the one in the figure below: Than I'm going ...
1
vote
1answer
45 views

Automate Noise Sensitive Designs of SMD For 95% Sensitivity [on hold]

I am thinking of automating my noise sensitive designs of high sensitivity in SMD: maintain 95% signal sensitivity by adjusting the factors (1-3) in the thread What is the best way to layout a PCB ...
2
votes
1answer
87 views

Mic preamp, fixing noise and gain issues

I'm trying to fix a preamp (made by a colleague) that's noisy and somehow not amplifying enough. I should say right away that this project is pushing the edge of my electronics knowledge so I have a ...
1
vote
1answer
62 views

Strange electrical noise from stepper motor

It's my first project using arduino. Simply trying to rotate three identical stepper motors, using three 293d h-bridges. Although it does work properly (meaning the motors do rotate as they should), ...
6
votes
2answers
120 views

Probing with Oscilloscope Stops ADC Fluctuation

I've gone back to my constant current project to fix an annoying fluctuation in the required current display. See schematics below. The entire circuit consists of a CCS section with signal outs for ...
2
votes
3answers
219 views

Where are these 50Hz noises from?

Circuit structure: An AC to DC power converter MeanWell 220V to 5V. The output is 5V. The power grid runs at 50Hz. We build DC-DC converters(Power Module) with multiple orders of Low pass filters ...
8
votes
4answers
637 views

Remove audible noise generated by buck converter

I'm dealing with a buck converter using an ISP452, an inductor and a capacitor to act as a buck converter driven by a PWM signal coming from a microcontroller. Some part of the circuit is producing a ...
-1
votes
2answers
41 views

How electronic device affected by electromagnetic interference? [closed]

I want to know how electronic device affected by electromagnetic interference? For example: Touchscreen device scanning as 190Hz, when noise source around (such as power supply) generate 190Hz noise ...
0
votes
1answer
45 views

What would the best way to filter high frequency noise? Decoupling/Bypass Capacitor? 1:1 Audio Transformer?

As many high end graphics card have high frequency coil whine and my particular one is causing whine on my diy studio monitors, what would be the best way to filter this noise? My studio monitors are ...
0
votes
3answers
99 views

How to reduce tape hiss while recording a cassette tape with digital data as source

I bought a few Maxell cassette tapes, a portable Sony cassette tapes recorder (with the possibility to record also from an external microphone: in my case, a jack connected to the PC) and - as already ...
1
vote
1answer
55 views

Is Voltage Divider a Noisy circuit?

I want to design a voltage divider circuit to bias an op amp, this circuit will be a part in another circuit to measure a biomedical signal. Is there a noise issue arises from using voltage divider ...
1
vote
3answers
106 views

Resistor noise equation gives infinite noise for an open circuit?

The thermal noise power from a resistor is p = 4kTR where: k is the Boltzman constant, T is temperature, R is resistance. Since an open circuit has infinite resistance, it would produce infinite ...
0
votes
1answer
27 views

Noise figure of a passive network at a temperature different from room temperature

Given a passive network at room temperature, the noise figure is the ratio between the output noise power density pw and and the output noise power density due to the source pwS F = pw/pwS = ...
1
vote
2answers
39 views

WWVB antenna interferance from AC/DC converter supply

I'm working on a design that uses a WWVB antenna receiver.... The WWVB antenna is a small (~ 1/4" x 4" rod). Size is not a constraint so I could make it much bigger if a I half to. The design is ...
1
vote
1answer
65 views

What is causing a loud static POP when PTT mic is keyed?

Hi folks! I have been investigating this static POP noise problem for a while now, including talking to the sound shop I bought the amp from and consulting with the manufacturer of the amp. I am ...
-1
votes
3answers
53 views

High current voltage reference from a small current constant reference and regulator

Say I need a high current voltage reference. A very accurate and low noise part is available, but can only supply 10mA and happens to be expensive. So multiples of this part cannot be used. What if we ...
5
votes
1answer
88 views

Optimal tradeoff between ADC bit depth and sampling rate

I have a 24-bit ADC sampling at 31250 samples per second. I am collecting these on a wireless device, and sending them in real-time to a PC for recording (and later analysis). My band of interest is ...
0
votes
0answers
36 views

Understanding problem and please advice or suggestion for sensor supply situation

i have 16 Channels Data Acquisiton Device for analog output sensors. I am troubling with strange noise problem with my sensor supply circuit. Before telling my issue, i explain my system requirements: ...
2
votes
1answer
103 views

electronic interference generated by blood? [closed]

Hi so i made a little electrical signal detector that can detect electrical interference/noise(for example putting it near a light or plug makes it squeal). I was messing around with it and noticed it ...
2
votes
2answers
146 views

If two resistors were connected in parallel and one was heated, would current flow due to johnson noise?

Increasing the heat of one of the two resistors will increase the Johnson noise in that resistor. This will generate a noise voltage across the resistor, will this essentially convert the heat energy ...
4
votes
1answer
125 views

Are these EMI noises?

I have always heard about EMI noises but have not really meet them or measured them. Our system composes a MCU running at 168MHz and a 16-bit DAC which is supposed to provide high-precision voltages ...
0
votes
1answer
56 views

Noise in simple BC547-Raspberry Pi GPIO doorbell?

I've connected a Raspberry Pi to my Friedland "Ding Dong" doorbell. The doorbell has two (apparently unused) terminals, over which there seems to be a stable voltage of 1 mV when the button is not ...
0
votes
0answers
67 views

Understanding the Sharp IR output measured by arduino

Sharp IR output was varying a lot about some value dependent on the distance at which it has an obstacle before it. So, I wanted to observe the variation. Hooked up to oscilloscope and observed a very ...
1
vote
0answers
36 views

What's necessary to properly decouple/filter a PWM-controlled fan from an Arduino?

I've got a small problem I could use some help with. I am using an Arduino to control a cooling system I am building for a DSLR. Primary goals are to use PWM and some pots to control TEC power, as ...
1
vote
2answers
117 views

Arduino: How to read sensor without common ground?

I want to analogRead() the voltage coming from a plasma cutter and serial print it. The problem is that the serial communication between my laptop and Arduino are breaking as soon as i turn on ...
0
votes
0answers
72 views

Reduce power supply noise for pH measurement with Arduino module

I'm very new to the intergrated circuits and I'm trying to make a pH sensor with Arduino UNO and a cheap pH module. The pH module is connected to analog input pin of the Arduino. I have to use a DC/DC ...
8
votes
3answers
685 views

Is it possible to pick up noise in an audio circuit through the ground / earth wire?

In an audio circuit, such as a guitar's electronics (the only thing I ever dabble with!), I have always thought (probably simplistically) of every point along a continuous earth path being essentially ...
1
vote
2answers
75 views

how can i filter this spikes on FFT?

i am working on very low amplitude signals and sensors. I have recorded one hour data. And i am looking its FFT graph. You can see FFT image. My question is that, what can cause the spikes in FFT ...
0
votes
1answer
59 views

White noise generator transistor voltage question

I have a very newbie question. Here is a white noise generator schematic I'm using (from http://montalk.net/emwng.html) It all works fine. What I want to understand is why this works at 9V (and ...
4
votes
2answers
91 views

How to stop Car Alternator audio noise / buzz?

I connected a Raspberry Pi 2 in the car to add OSMC media player capabilities. However, there seems to be a buzz / hum of background noise in the audio. The noise is correlated to the engine speed so ...
3
votes
2answers
70 views

Ribbon Cable Noise Susceptibility

As part of a product upgrade we are looking at replacing looms of wires bound together by cable ties or spiral wrap with ribbon cable. We are doing this to try and cut cost and assembly times. We are ...
1
vote
1answer
129 views

Microcontroller GPIO in audio circuits

I'm designing an analog synthesizer, which is controlled by an STM32 -microcontroller. In several parts of the circuit, I intend to use a GPIO pin to control switches in the circuit, and in two ...
0
votes
0answers
26 views

SQNR for different step sizes in quantising the same signal

Assume a random signal uniformly distributed between +5V to -5V. Here, for positive and negative halves i get two SNRs. For positive half 0 to 5v ; number of bits =7 and SNR = 43.6dB. while for ...
1
vote
0answers
41 views

How can shot noise be dependent on dc current, not instantaneous average current?

After looking at the formula of shot noise and its derivation, I thought current in shot noise refer to instantaneous average current, not dc current. By instantaneous average current, I mean current ...
15
votes
4answers
238 views

Is it sensible to always use larger diameter conductors for carrying smaller signals?

This question as originally written sounds a little bit insane: it was originally asked to me by a colleague as a joke. I am an experimental NMR physicist. I frequently want to perform physical ...
6
votes
2answers
613 views

Where is this noise coming from? 200 kohm Wheatstone bridge

I have a Wheatstone bridge I want to use to measure a resistive sensor. At the moment, all four arms are fixed resistors, while I get the circuit set up. The noise in the circuit is much larger than I ...
1
vote
1answer
42 views

Should cable shield connect to ground plane on hand-held tethered device?

I am designing a hand-held device whose power and signals come from a cable. The device circuit will be +5 volt and powered through the cable. The cable (a re-purposed HDMI cable) has multiple ...
0
votes
1answer
61 views

Noises generated by OpAmp driving 50 ohm load

I am trying to drive a 50 ohm with 300mV, 15khz sine wave using an OpAmp. The chip I am using is ADA4610. However, I found that there are noises of 15kHz(4mV Vpp) and 30kHz(3mV Vpp) at the power ...
0
votes
0answers
46 views

Noise in Sound Card Oscilloscope

I have created an oscilloscope by following Instructable. I am getting signal but I am getting noise. Too much noise. Is there a way to minimize this? I am using any shielding. If I should use, please ...
0
votes
0answers
72 views

Using USB 5V to power a 24 bit spectrum analyzer?

I want to make a USB spectrum analyzer based off the ads1675 4MSPS, 24-Bit ADC (1.9MHz Bandwidth) and was wondering what I should do for power. This project is meant to be practice for real world ...
5
votes
1answer
146 views

Encoder PCB design - grounding, noise and decoupling

Hi first time posting here. There always seems to be helpful answers and tips. Okay my question is simply are there any glaring mistakes in my approach to the PCB layout (see image links below), I'm ...
0
votes
0answers
34 views

audio signal unwanted spread removal

I am trying to get rid of some perodic high frequency sweeps belongs to a Acoustic Doppler current profiler. As you may see in spectrogram (vertical axis is frequency and horizontal axis is time) i ...
1
vote
1answer
55 views

CMOS Gate and Coupling Noise from Loose Wires

I am currently working on this small circuit which as you can see, has to level shift a 3.3v 1Hz PPS signal into a 5v pulse. Everything is marvelous when I measure the level shifted pulse with ...
0
votes
2answers
66 views

How to remove mains hum from a BNC cable?

BNC cables are used as inputs to a data-acquisition hardware. If long BNC cables are picking up the 50/60Hz mains hum through the air like antenna, how can I filter this? Would connecting the BNC ...
0
votes
1answer
85 views

What could be the reason for 50Hz noise with isolated input signals?

A PCI data-acquisition board has 16 referenced single-ended channels. Here is the board: http://www.mccdaq.com/pdfs/manuals/PCI-DAS6034-35-36.pdf I'm using all 16 channels with BNC cables. The two ...
0
votes
0answers
52 views

Mains hum on battery-powered prototype

Beginner's question. I have a battery-powered MSF ("radio-controlled") clock running on 1.5-volts. I am aiming to use it's alarm output to provide an accurate "time signal" for other equipment. The ...