Questions tagged [noise]

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

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112 views

Reduce Noise Added With Zener Clipper

I'm working on a hobby Arduino project to create an audio visualizer using an LED strip. I'm using the MSGEQ7 to separate the signal into 7 bands, then send it to a Wemos D1 Mini. I started by ...
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36 views

Phase noise of a digital PLL

I assume the reader is aware of how a DPLL works. The DPLL oscillates with a frequency of \$F_{out}\$. The DCO free running frequency is \$F_{free}\$. In the model of our DPLL we've only considered ...
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1answer
22 views

Mitigating noise pickup from contactor turn off

I am working on an industrial control system that uses a microprocessor to control a bank of 6 contactors. The contactors have 120V coils. When all of the contactors turn OFF at the same time, they ...
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2answers
41 views

EFT Design training

My team is responsible for designing industrial electrical devices. We had successfully designed several devices before. Recently, we are designing products that have to meet IEC 61000-4-4 class A ...
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1answer
49 views

Would leakage through a JFET create thermal noise

The impedance through the gate of a JFET is very high and leakage current very small. Would this impedance act like a large resistor creating thermal noise? Would this be a low noise way of ...
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1answer
33 views

What is meant by the term “baseline noise” in this context?

I came across this article about oscilloscopes. Under the figures and scope screenshots there is a term called "baseline noise". I googled but it turned out this baseline noise is used at different ...
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4answers
2k views

Do I need a 50/60Hz notch filter for battery powered devices?

Given that battery powered devices are not plugged in the mains power, can I assume that there will be no 50/60 Hz frequency noise? This question came up while thinking about what the circuit for a ...
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4answers
3k 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 ...
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3answers
893 views

LM386 amplifier buzz when not connected to signal

I've set up a simple LM386 amplifier on a breadboard according to the above schematic. When connected, the amplifier works like a charm driving a spare 8Ω speaker with impressively low (audible) noise....
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1answer
101 views

Good PCB Design - Single Power Plane with 2 Power supplies (+ve & -ve)

Recently I've taken over a project which requires low noise but the design given to myself does not meet the requirements. I noticed on the PCB design It has a single Power Plane with 2 separate ...
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39 views

Is there a (sane) way to diagnose and resolve these EMI issues? [closed]

A friend sold me their vintage turntable and receiver. Turntable is a Philips 437, Receiver is a Scott 355R. For reference I've listened to this exact setup at their house and never noticed issues, so ...
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1answer
65 views

Downsides of 3-terminal capacitors and LC filters for power supply to IC

I read the Murata application notes on power supply decoupling and noise filtering. I guess it works great as advertisement because I now want to replace all the decoupling capacitors to my analog-...
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1answer
179 views

Equivalent noise resistance(s) - 2 stage amplifier

I came across this question in my textbook: The first stage of a 2-stage amplifier has a voltage gain of \$150\$, an input resistance of \$1500 \Omega\$, an equivalent noise resistance of \$700 ...
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1answer
40 views

summing amplifier output [on hold]

i amplified 2 audio signals using lm386 ics separately,and gave both the outputs as input to ua741 ic,to be used as a summing amplifier.I am not able to get any output at the speaker from ua741,not ...
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1answer
658 views

Shunt Current measurement noise

I was measuring current through shunt method. below is the SCH and waveform captured. PB5-AI will to ADC which has max 1 Volt limit. Waveform capture across R30 So why this much noise on output ...
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6answers
2k views

Why does this potentiometer in an op-amp feedback path cause noise when adjusted?

I have placed a dual-gang 100k potentiometer in the feedback path of two op-amps that work as a Sallen-Key filters. This controls gain but also the Q factor of the filter (somewhat demonstrated on ...
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2answers
259 views

How to reduce noise in this circuit?

I'm using a Raspberry Pi in a circuit I'm building that includes a few elements. Elements in the circuit: PWM driver to control 3 servos Mic board for recording Class D Amplifier that drives 2x3W ...
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1answer
75 views

TSOP34838 noise in dark areas

I'm using a TSOP34838 IR reciever on an ATMEGA MCU, However, I see a problem in dark areas... If I put my finger in front of the receiever, it starts spewing out garbage, even worse when the room is ...
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0answers
57 views

How to remove DC power supply noise while load is active?

I'm using a breadboard power supply to power up two STM32F103, two Hall flow sensors, one IC555, and one 16x2 LCD with backlight. While everything is connected I have alot of noise in the system which ...
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1answer
2k views

Noise problem with buck/boost switching regulator

I am designing a electrical device for a research project (I'm a PhD student, but unfortunately not EE!). More info on the device can be found at http://iridia.ulb.ac.be/supp/IridiaSupp2012-002/ The ...
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1answer
122 views

How can I couple relay chattering noise to a data cable?

How the chattering of relay causes noise ? Is it its on-off sound makes the noise? I want to know how to couple a relay chattering noise to a data cable.
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3answers
179 views

Voltage regulation for Atmega328p

I am designing a circuit containing two Atmega328p. First chip will drive TFT screen with 3.3 V linear voltage reg. Second one will drive BT module, couple of relays, two sensors, SD card module, and ...
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1answer
77 views

Triac dimmer makes audible noise (hum or buzz)

I have some triac dimmer from IKEA (bought several years ago). This dimmer makes audible noise (hum or buzz), very notable during night when it is placed on a bedside table. I failed to find the ...
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2answers
179 views

S/N Formula with probability

Hello I am looking for the S/N formula that incorporates the probability of catching the signal, and setting an arbitrary treshold level above which we detect the signal. I can't figure out the ...
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1answer
25 views

Does the probability distribution of cosine transformation of uniformly distributed R.V. depend on phase shift of the cosine function?

Suppose, x is uniformly distributed over [0,2π], and y = cos(x + ∆), will the probability distribution function of y depend on ∆? Is my solution to find out the Probability Distribution function of Y,...
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3answers
100 views

perceived loudness of noise vs. sine wave

I am trying to understand what gains I need to use each for a white noise generator and a pink noise generator for a human ear to perceive the loudness to be the same as it is for a 440 Hz sine wave ...
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0answers
22 views

How to reduce noise for arduino capacitive sensing

I have an artistically-painted 5mm-thick wood panel that I want to use as a light switch without alteration to the image. My solution was to (try to) make a specific region on the panel touch-...
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2answers
246 views

Noise resilient, hot-pluggable communication bus over long cables?

I'm working on a setup, where we need communication between a master device and several slave microcontrollers distributed out in different boxes connected by "long" cat5e cables (3-10 meters) The ...
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6answers
3k views

How to combat noise from my circuit polluting my 12V rail?

I made a controller for 12V DC fan. It is basically a buck DC-DC converter controlled by voltage. It regulates voltage for fan from 3V (lowest speed, fan draws 60mA @ 3V) to 12V (full speed, fan draws ...
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1answer
187 views

Bluetooth audio circuit noise problem

I am working with a bluetooth audio circuit. I am facing noise problems in the mic input so I used B0505S DC DC isolated module. It worked but now when I printed a PCB of the same circuit and I am ...
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3answers
57 views

Frequency/amplitude modulation and SNR

I read (for instance here) that FM modulation is less affected by noise than AM modulation. But I don't understand conceptually the reason for that: why is the SNR with frequency modulation higher ...
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1answer
153 views

Which design to choose for highly stable LED or laser diode driver?

I'm looking at several design choices for driving a LED and/or laser diode in a very stable, low noise way. The specs are as follows: current: 1-100mA, adjustable (the adjustment can be either ...
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1answer
121 views

Noise in FET reverse-polarity protection for ADC

I have quite precise ADC circuit. I want to protect input supply voltage (not ADC input) from reverse-polarity using FET transistor as shown on the picture below. I wonder: is there any noise / worse ...
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2answers
231 views

How do wireless receivers reject noise created by the original signal reflecting off walls?

When a transmitter emits an RF signal it reflects and bounces around all over. If a receiver is line-of-sight with that transmitter then the original signal will hit it first but signals bouncing off ...
2
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1answer
177 views

How to reduce the effect of electric lighter noise on Micro controller?

I am using a kind of electric lighter in my circuit in order to turn the fire on. And also i have used some sensors that alert in danger by sending a signal to the MCU (ATmega 32) interrupt. The ...
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1answer
67 views

Noise in portable power supply to guitar effects pedals [closed]

I am constructing a battery powered power supply for a guitar effects pedal board. There are 5 pedals and I am using a phone charging battery and a boost converter to supply 9V (centre negative) to ...
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1answer
49 views

LED Strips - Data Noise Over Long Distance Between Controller and First Strip

Please refer to the above picture. The black line is the ground wire and the green line is the wire carrying data. First Question In regards to data noise/interference, can the output ground wire ...
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2answers
220 views

Maximising entropy generation rate via an ADC's reference voltage

I have a circuit that generates random noise which I've measured with a 10 bit ADC. The following is the sample distribution:- You will notice that it's a log normal distribution, characteristic of ...
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1answer
32 views

Does swapping the inputs cause increase in the common mode noise in this scenario?

This is a question I wanted to ask after I have observed much more noise when I swap a filtered traducer's output to a single ended data acquisition board. A transducer outputs Vs1 signal. The ...
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1answer
75 views

Removing noise from TDA2007A Audio amplifier circuit

I have built an audio amplifier circuit like the test circuit in this TDA2007A datasheet I am going to use this circuit with Raspberry Pi 3B+ and going to feed sound via 3.5mm of Raspberry Pi to this ...
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1answer
88 views

Noisy op amp buffer

I made an op amp buffer using a TL071 for my guitar but it is very noisy. The circuit is a simple follower. Originally I had no feedback resistor but I added it later in case it decreased the noise ...
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1answer
92 views

Questions about a design for an SMPS post regulator filter circuit?

For minimizing SMPS ripple and especially noise, I’m trying to make a small interface which is a post regulator cascaded after an LC filter. I have come across some papers related to this topic and ...
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2answers
313 views

How close to a stepper motor do I need to shield the wires?

I am trying to shield the cabling on my CNC mill. The motors, unfortunately, do not have connectors but instead have wire leads coming out from the motor housing. I can cut those wires about an inch ...
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1answer
26 views

Confusion with applying incremental bandwidth to measure noise power spectral density

From a text, regarding the following paragraph about random noise: Being not very informed on this topic, I don't understand what meant by the following statement: "If such a measurement is made ...
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0answers
39 views

How does one calculate output voltage noise of a current output DAC?

I am using a current output DAC connected to a voltage reference and a transimpedance amplifier. I know the noise characteristics of the voltage reference and the amplifier. The DAC simply lists "13 ...
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1answer
55 views

What is the relationship between dark current and the contribution of dark noise in a photodiode?

For example, if I have a datasheet for a photodiode that lists a dark current of 1000nA. I have a transimpedance amplifier with 1kohm transimpedance and 1 mV voltage output voltage noise. Presumably ...
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0answers
31 views

Low-Speed CANbus Common-Mode Choke Insertion Loss

I'm designing a low-speed CAN transceiver breakout-board (schematic below) and I'm trying to select the proper choke to use to reduce common-mode noise. I've found a few common-mode chokes meant ...
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0answers
50 views

Differentiator circuit sees noise on PCB after 2 min

I'm new to PCB design, and looking for some advice. I designed a PCB shield and I'm seeing a lot of noise in my differentiator circuit. The circuit will run perfectly for about 2 min and then all of ...
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1answer
40 views

Series regulator noise levels

When using multiple regulators in a chain, is there noise added to the input by the regulator? If I have a SMPS feeding an LDO, and then another SMPS after the LDO. Is the ripple or noise added to ...
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1answer
176 views

Induced power supply noise on switch contact

I have a circuit that has a 24V section and a 5V section, separated by opto-isolators and an isolated DCDC converter. Both sides of the DC-DC have decoupling caps, and the MCU has one per Vcc pin. ...