Questions tagged [noise]

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

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31 views

Suppressing Noise without Earthing

We have designed an HMI, which will contain a 10.1" TFT with PCAP touch panel. I am using an enclosed power supply to convert the 230V AC to 12V DC. Only DC positive and negative is connected to my ...
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54 views

How to protect my 555 timer against DC motor noise?

I have this circuit: (Sorry for such a bad schematic.) As you can see, there is a DC motor that gets power from 12V source, using a NPN transistor controlled by a 0-5V signal. Please note that ...
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3answers
92 views

How to choose R and C to reduce noise on analog input of arduino?

I'm not terribly proficient when it comes to hardware, so please bear with me. I've tried to google around to figure out how to choose values for a low pass filter to reduce noise on a potentiometer. ...
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46 views

Thermal Noise autocorrelation and time domain analysis

I have some doubts about the termal noise of a real resistor. The equivalent model of a noisy resistor is this one (here the reference): Here there is the model of a noisy resistive network: I ...
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1answer
49 views

XS-3868 module stops noise for 5 seconds, how to make it longer

I've made a bluetooth audio receiver using XS-3868 module (using this diagram) and connected a TP4056 charger module and a lithium-ion battery too. Everything works fine. When the charger module is ...
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25 views

schmitt trigger and noise

I know that a Schmitt trigger is used to reduce noise in a circuit, but why does noise need to be reduced. How does noise effect the overall circuit and what benefits do you achieve by reducing noise ...
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2answers
95 views

What makes noise heteroscedastic?

I work in the field of spectroscopy, for instance NMR and FT-IR. For both of these instruments, the advice is to process the data to compensate for heteroscedasticity -- noise that increases as the ...
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1answer
91 views

Fan is causing noise in the circuit

I'm in the process building a linear lab PSU, the fan which is supposed to cool the heatsink is causing 6 mV peak to peak noise at the output of PSU. It's a 4x4 cm brushless chinese fan with unknown ...
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54 views

Ripple on tens-millivolts sinus waveform

I’m trying to make a DDS to generate a sinusoidal signal with tens to hundreds of millivolt amplitude and hundreds kHz frequency using an LTC1666 DAC. But I have some confusing results. Device ...
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2answers
151 views

SDA pin on I2C lines seems weird

I am trying to analyze the I2C commands sent by a PC software to R3910 DSP chip The software uses a programming box (provided by the same company that manufactures the R3910 chip) to communicate ...
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2answers
67 views

Fixing power supply interference issue (?)

I am working on a project that involves controlling WS2812B led strips using a Teensy 4.0 microcontroller. I got everything working during the testing phase, but now, after transitioning from ...
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6answers
2k views

Decoupling Capacitors: What happens to the DC on the cap once noise is introduced and it shorts?

simulate this circuit – Schematic created using CircuitLab I've been using decoupling caps for a while now and I understand their purpose in keeping DC signals clean since capacitors allow high ...
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33 views

Do I use this equation for a Friis law question

I am just puzzled as the question gives two gains. The question is below input receiver has a noise figure of 4db and a power gain of 5db. It is followed by a mixer stage of with a noise figure of 3....
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209 views

Understanding the circuit diagrams for white noise generators

I'm a huge neophyte when it comes to electronics, and I'm trying to work out how to create a white noise generator for a project. I've been looking at some to base my examples off of. One of which is ...
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37 views

How do I connect noise reduction capacitors for “stacked” TI REF102 chips?

The datasheet for TI's REF102 shows a method for "stacking" multiple ICs to obtain voltages in multiples of 10V. Two stacked REF102 ICs gives you 20V, 3 gives you 30, etc. I've tried hard to copy the ...
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37 views

lots of 3d sound in handsfree [closed]

My earphone gives lots of 3d sounds and when i eject little bit it sounds good, actually i’m repairing i-e change of jack. Kindly help Your reply will be highly obliged.
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1answer
51 views

Is noise density over a bandwidth a measure of the noise's standard deviation?

Suppose I have a sensor which has a dominant white gaussian noise source, a \$1\textit{unit}/\sqrt{Hz}\$ noise density and a bandwidth of 100Hz. Then the noise becomes 10\$units\$. Is this a measure ...
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1answer
70 views

How to measure Johnson Noise precisely experimentally?

I want measure Johnson Noise across a resistor having certain over the certain range of frequency or bandwidth practically. I am starting from scratch, how can I build circuitry and instrumentation so ...
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43 views

How close can an output transformer be to a preamp tube?

Imagine a layout for a tube amplifier. The power transformer is on one side, and the output transformer, input jack, and preamp tubes are on the other side. (Take a look at the Soldano SLO for example)...
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2answers
85 views

Is capacitor noise due to observed step charging?

According to Tom Bearden and Per Wallander the capacitor step charges and step discharges. Se for example Per Wallander, My way of understanding electromagnetism, section 2.3 page 13: What we see ...
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1answer
188 views

Thermal Noise in Oscillators

let's consider this circuital model for an LC oscillator in which the parasitic resistance R is affected by thermal noise (represented here with an equivalent noise current source, according to the ...
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1answer
76 views

What does these heatsinks do?

I think sharing the video will be the easiest way of describing the situation. The transistors are electrically isolated from the heatsinks, I have checked with multimeter. Few days ago, I have ...
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50 views

Why connecting oscilloscope reduces noise [duplicate]

I am doing a speaker driver circuit. When I connect the oscilloscope probe to the output (emitters of npn/pnp complementaries) to where also the speaker is connected; the sound of speaker and the ...
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2answers
155 views

Johnson Noise Measurement

How to measure Johnson Noise precisely practically? I tried using opamp/ low noise amplifier in cascade with band pass filter followed by multiplier circuit (squaring signal) and measured output ...
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137 views

Where might the noise be coming from in this speaker driver circuit?

Well, it will be a broad schematic. To summarize, there my approach is: Yellow part is for oscilations at three different freqs(around 0.8 - 2 kHz, different for each of the three signals), ...
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4answers
2k views

Should I ground the heatsink?

I am using an npn transistor in TO-220 package, and its collector is electrically connected to the metal part on it. I have checked it via a multimeter. I use a heatsink for that transistor, with ...
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2answers
65 views

Johnson–Nyquist Noise of Open Circuit

Johnson–Nyquist Noise increases with resistance - so does it become infinite for an open circuit? Specifically why is the input to an oscilloscope that is not connected to anything not completely ...
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1answer
21 views

Reactive Input Impedance for Current Noise

I am reading about op amp noise in the app note here. Page 3 mentions: "Current noise is only important when it flows in an impedance, and thus generates a noise voltage. Maintaining relatively low ...
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28 views

Ethernet Link is going down while applying EFT pulses on Power Port

We have conducted our system for EFT test as per IEC-61000-4-4. We have applied EFT on the AC side of the AC-DC power supply. We are using the power supply HWS50A-12/A from TDK-Lambda. As per the ...
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1answer
47 views

Ground offset or common mode noise voltage

This is just a small doubt I would like to clear. Suppose I have a buck regulator providing output at 5V and 1A. Suppose I measure the output voltage at the ground pad of the output capacitor and it ...
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2answers
54 views

Very long PCB trace causing microcontroller to wakeup?

I have a design where I'm using an ESP32 as the device's main controller. The system is battery powered, so the ESP is in deep-sleep a lot. It can be woken up with a simple button push (detecting for ...
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60 views

Noise generated by monitor from Word document

I was zooming in and out of Word documents of only text and noticed that a noise was produced. The noise increased in pitch as I zoomed out and decreased as I zoomed in. I tried changing the font ...
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2answers
87 views

Obtaining Accurate Measurements from Strain Gauge

Background I have a strain gauge that I need to obtain measurements from. The product page indicates that the sensor is a half bridge configuration (one active/one compensating element). The sensor ...
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33 views

Purpose/Difficulties of having a common mode choke

This question is related to common mode choke. I know I have asked this question a couple of times in this forum and I have also read related questions and answers. But I am not able to get the total ...
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1answer
36 views

How to conclude the nature of interference for such scenarios?

This is abit a hypothetical question. Imagine a signal chain where a AC-DC power supply is powering a transducer and the transducer output is coupled to a data acquisition input by a BNC cable. Or I ...
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1answer
55 views

noisy power supply for electric guitar pedal

I'm building a pedals board for an electric guitar. In order to have better integration, I replaced the wall wart power supply that was doing the job by this (BTW, the wall wart power supply is also a ...
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1answer
81 views

Low pass LC filter goes “wrong” with capacitive load

I have been experimenting with this circuit: simulate this circuit – Schematic created using CircuitLab Vin has a lower frequency ripple of 2V and a high frequency (switching?) noise of 6.5V. ...
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2answers
73 views

Order of op amp cascade to reduce noise

I am currently designing a little circuit to amplify a weak signal with two sequential op amps. To reduce the noise at the output of the two amplifiers, what would be the best order to place these ...
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1answer
67 views

Optical displacement sensor noise and current to voltage conversion

I'm currently involved in a project with the aim of measuring the tremor of mice limbs (displacements of about 100 um). The sensor my group has chosen is TCRT5000 (Vishay), but we are facing several ...
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1answer
49 views

How do I convert a Eb/No from a dB value to a linear value

So for example how would I convert an Eb/No value of 2dB into a linear value?
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1answer
32 views

Balanced impedance CM and DM stages EMI Filtering

Here is the following assertion : I would like to understand why line impedance imbalance can cause CM noise to get converted into DM noise ? Thank you very much !
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1answer
48 views

Ground Antenna Madness?

When I hold my oscilloscope probe and ground clip out in the air, I get a noisy ripple with a predictable pattern. Nothing unusual here. When I touch the tip of the probe to the ground clip, I get a ...
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1answer
39 views

Effective impedance calculation for noise removal from supply

I am working on single supply Op-Amp amplifier, referring to this post. While calculating the value of the capacitor C2, as to pass all the noise from the supply to the ground. I am unable to ...
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1answer
74 views

How to generate different noise in LTspice from run to run

I'm trying to simulate noise in my circuit, and ideally want to get a histogram of a certain parameter affected by that noise over many runs. However, when I use the white() command in LTspice, or ...
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3answers
57 views

How to improve SNR by averaging multiple identical sensors - hardware or software?

My application uses a MEMS microphone amplified by an AD8429 instrumentation amplifier with a bandpass filter to acquire signals. The phenomena I'm measuring occurs at a specific frequency and so I ...
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1answer
51 views

Noise on probe while measuring Switching Frequency of Buck Converter

I have a buck converter and I am measuring the voltage ripple at the output capacitor along with that I am measuring the switching frequency at the cathode of the diode. Please refer the below image. ...
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2answers
90 views

Can this be CM related noise?

In a single ended data acquisition system a DAQ board is sampling channels in a multiplexed way. The DAQ is single ended as well as the input signals. When I use two analog transducers coupled to two ...
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23 views

From noise spectral density to equivalent short circuit input RMS noise

I have an acquisition system that is supposed to be low noise. It acquires from an ADC into a wav file. I read this file and process it with Matlab. Then, being "x" the array with time signal, Fs the ...
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61 views

Op amp output voltage swing vs noise

Staying within an op amp's specified output voltage range, how does a difference in output swing affect the op amp's noise applied to the output signal? Obviously by increasing gain, we amplify the op ...
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2answers
51 views

Problem with transient on power rails

I have an AC to DC converter that outputs 5V. I then run this into 2 regulators on my board. The 4.2V regulator goes into a cellular module, and the 3.3V regulator goes into a microcontroller. I ...

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