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Questions tagged [noise]

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

6
votes
3answers
426 views

resolution bandwidth

I have the following trivial question: I have acquired a noise spectrum with a resolution bandwidth of \$124\mathrm{Hz}\$. I would like to convert it to \$\mathrm{V/\sqrt{Hz}}\$. Shall I simply ...
-2
votes
0answers
47 views

What's best for separating signal from noise, lock-in amplifier or averaging with digital oscilloscope?

Or isn't there a best one but maybe they are good in different scenarios, say that the noise is 10 times bigger than underlying signal, which one is to be preferred? Similarly, if the noise is say ...
0
votes
0answers
25 views

vintage amp component popping and crackling [on hold]

Hi i have a vintage pioneer sx-650 recevier when I plug it in I hear a light poping / white noise sound coming from around the transformer area not Shure if it is the electrlitic compassitors or if I'...
2
votes
2answers
75 views

Johnson-Nyquist noise for a lossy inductor?

In searching the internet for thermal noise on an inductor and I'm not finding much on the basics for a real lossy inductor. I'm interested in thermal noise for a fixed inductor in a surface mount ...
0
votes
1answer
42 views

Low pass filter vs low noise regulator

I’ve been spending a lot of time looking at different low noise voltage regulators, and it dawned on me-why am I not just putting a filter on the output of the regulator I already have? What are the ...
0
votes
1answer
53 views

schmitt trigger causes noise

I am trying to get a 74HC14 hex inverting schmitt trigger to work. First thing I did was connect it to a power supply. When I connect the Vin and Ground ports to my bench power supply (5V), some ...
3
votes
1answer
46 views

Headphone Noise from Laptop SMPS

I have been facing an issue that has been a mystery to me for quite some time, and I wanted to see if someone here can potentially give me more insights on this so I can understand why it is happening....
-1
votes
0answers
32 views

Problem with ground loop in audio system? USB and minijack at the same time [on hold]

My hardware setup is: PC with external USB audio card + smartphone. Smartphone is connected via USB to PC and via minijack to USB audio card at the same time. Problem doesn't appear when I disconnect ...
2
votes
2answers
90 views

How to reduce thermal resistor noise in filter circuit?

I'm taking some measurements from a bio-sensor (using an INA) that operates on the a few to \$100\ \mu V\$ scale. Because of 50/60 Hz EMI, I plan to apply a notch filter (NF) of the Twin-T or the ...
0
votes
0answers
39 views

Reduce wake-up noise on ARM CM3

I need some help exploring a solution. I have an ARM Cortex M3 MCU, which has low-power sleep mode implemented. Wake-up sources are any GPIO pin, or an RTC alarm. A terminal is connected to UART-0 ...
0
votes
0answers
18 views

Noise in DC/DC Converter QHL600300S12 (180V-425V to 12V) output

We are using a DSO TDS2022B from Tektronix to check output voltage of DC/DC Converter QHL600300S12 from XP Power and were seeing 5V peak-to-peak in the 12V output power rail. What could be the ...
0
votes
2answers
45 views

Resources on Noise Circuits

Back when I was taking an RFIC design course, I was pretty disappointed by the noise part of the class, specifically calculating the output-referred noise voltage, noise figure of an amplifier, etc. ...
0
votes
1answer
60 views

Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it. However sometimes it starts to oscillate at 25 MHz, ...
0
votes
2answers
30 views

Noise testing method

I have Electronic board with power supply , control board etc. I wanted to conduct noise test . Is there any standard procedure available. I wanted to check if i induce the noise into power line or ...
0
votes
2answers
116 views

Mcu keeps reseting because of noise

I have a circuit in which there is a mcu lpc1768 and a gsm module sim800l. For power I use DC/DC converter and made a 4.2v using lm2576 for sim800l. Used that voltage, I made a 3.3v using ams1117 and ...
0
votes
1answer
36 views

How VFD affects an isolated IOT system

To avoid noise from the external system I tried to isolate the internal completely. So I added DC-DC isolated converter with signal isolation. I have attached the picture. Still when reading data and ...
0
votes
1answer
74 views

Practical considerations for a summing amplifier

The summing (usually inverting) amplifier is a classic op amp configuration. However, I'm struggling to find any products on the market which actually do this, leading me to conclude that I have to ...
3
votes
0answers
99 views

ADC conversion value spike during ADC conversion

Description of the situation I am trying to get an analog vibration sensor signal to a Raspberry Pi 3 B+. To convert the analog signal to digital values, I'm using Waveshare High-Precision AD/DA ...
0
votes
0answers
21 views

PSPICE Error in Second order High-Pass Sallen-Key Filter

As part of a class project, I'm trying to filter pulses with noise by implementing a High-Pass Sallen-Key Filter with the resistors replaced with transconductance amplifiers (schematic shown below). ...
1
vote
1answer
70 views

Is there a standardised noise source symbol for circuit diagrams?

Does anyone know of any standard symbol for a noise source, for example of one wants to represent the Johnson-Nyquist noise, what is best to use?
1
vote
0answers
28 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 ...
1
vote
1answer
61 views

How to remove the noise on the video of the DС-DС converter?

I had to make my own DC-DC converter on the TPS54360 driver. But because of the driver for two cameras are very strong interference. I want to try to isolate the driver GND and design it with a track ...
1
vote
1answer
52 views

Will two identical antennas next to each other pickup the exact same noise?

If you had two exact same antennas next to each other, say 10cm, or even wound together. Would they see the exact same noise? I'm thinking whether it would be possible to amplify a signal by ...
0
votes
1answer
52 views

Noise when amplifier and chromecast share a power supply

simulate this circuit – Schematic created using CircuitLab I want to power a chromecast and an amplifier from the same power supply. When the dc/dc converter is powered by a separate power ...
1
vote
1answer
49 views

Noisy rising and falling edges at the output of a schmitt trigger circuit

I wanted to replicate a comparator circuit to PCB and I later noticed that I mistakenly swapped the inverting and non-inverting inputs. The comparator used is LM2903. Surprisingly the board was still ...
0
votes
2answers
48 views

Which areas do I remove copper pour to reduce noise?

I have a 2 layer PCB that carries a microcontroller (Particle Electron), connects to a sensor with an ADC reading, has an ADC comparator IC, a watchdog timer IC, a PNP switch, an power bus and I2C ...
0
votes
2answers
36 views

Distortion is introduced when speaker is connected to the output of the amplifier

I have a circuit that implements a guitar amplifier (I ordered a couple LM386 but in the meantime I used an OP484). The following figure represents my schematic: (cap C2=10uF as well) The signal from ...
0
votes
2answers
90 views

How to measure uV voltages buried in noise?

I'm working on a project in which I am analogly processing ultra low signals. The phase, harmonics and signal shape are critical to circuit functions. The signal on the input comes from an antenna ...
0
votes
0answers
43 views

Bonding DC Minus to Ground with Resistor for Remote Power?

Layout: I have a system that has 3 serial networks that run a variable length with one central processor talking to multiple endpoints via Modbus RTU, Canbus, and another rs485 that talks a protocol ...
-1
votes
2answers
68 views

Reducing noise that grows with frequency

I have a project in university where my professor gave us the following problem: There is a transducer generating an AC signal with amplitude of 7.5mV and a frequency range from 50Hz to 150Hz. This ...
3
votes
2answers
103 views

How does placing cap between signal GND and earth GND solve common mode noise?

Thanks in advance for your time. I am reading several articles about differential mode noise and common mode noise. Among which I found the below 2 pretty instructive: https://www.murata.com/~/media/...
-2
votes
2answers
65 views

How to remove 50 Hz, 100mV noise? [closed]

I am getting 100 mV noise signal at 50 Hz. I do not know the origin of the noise. What should I need to do to remove it?
0
votes
2answers
54 views

Noise mitigation in +/-5mV instrumentation amplifier?

I am building a differential amplifier to boost a 0-5mV (delta) signal off a load cell wheatstone bridge. In simulation, the design works here (falstad): (for those who have not used falstad circuit ...
8
votes
4answers
857 views

How do PCB vias affect signal quality?

Is it bad practice to route high speed signals (like a SPI bus clocked at 4MHz) through PCB vias? I've noticed a good bit of noise (+-300mV) on my SPI bus signals with 3.3V levels. The signals ...
0
votes
0answers
67 views

Probing LPC bus with an FPGA yields gibberish — wiring problem?

I'm trying to repeat the TPM key dumping experiment by Pulse Security using a motherboard with Secure Boot and the same TPM1.2 chip onboard, equipped with Windows 8. However, when I connect the FPGA ...
1
vote
1answer
33 views

Interference from well pump pressure switch and microcontroller

I am using the Parallax Propeller to start and stop timers for an auto racing timing system. Out of 250 cars there were timing issues with about 10 or so. It was very random and hard to diagnose. I ...
2
votes
0answers
27 views

SMPS mains hum on guitar rig

My guitar rig consists of Guitar -> Audio Interface (Steinberg UR22) -> Laptop (via USB). I listen to the (processed) audio using headphones connected to the audio interface. ISSUE: When the ...
0
votes
1answer
37 views

Communication in presence of noise: Why is the number of distinguishable amplitudes K*sqrt((S+N)/N)

In section VII: The Capacity of a channel in the presence of white thermal noise in his 1949 paper Communication in the presence of noise, C.E.Shannon says, that for a signal with average power P, ...
0
votes
1answer
60 views

SMPS electrical noise issue

1I'm using class 2 medical graded SMPS in our device. So earth connection not recommended. When connecting SMPS to load (contains capacitive touch LCD), touch function is affected by SMPS noise. When ...
0
votes
1answer
74 views

What can be the cause for the servo to jitter continuously while powered?

I'm using an HS-785HB servo (https://www.robotshop.com/media/files/pdf/hs-785hb.pdf) for my project. I'm working on the Mbed platform and it uses C++. The servo library I use is Servo.h and I'm ...
0
votes
2answers
114 views

Removing noise induced by IC (Ground loop?)

I want to build a simple, portable, MP3 decoder + amplifier. I use a PAM8610 amplifier and a generic MP3/bluetooth decoder. When I power each of them from separate batteries (7.4V) it works nicely. ...
2
votes
1answer
48 views

Relay+SMPS = Noise in RS-485 bus

I designed a board with a microcontroller (Atmega328), 3 relays and a RS485 transceiver. The relays control SMPS LED drivers (Meanwell LPF series). The system consists of 10 boards, each one ...
2
votes
1answer
122 views

Signal noise cancelled by touching the leads

I have a pressure sensor that outputs 0.5V with a +/- 20 mV noise. I am trying to identify the root cause of the noise using an oscilloscope. The noise occurs in waves of twice the mains frequency, ...
-1
votes
2answers
72 views

LED strip is flickering, but when I touch the data wire to the Raspberry Pi, it's almost fixed

simulate this circuit – Schematic created using CircuitLab Figure 2. Schematic tidied up by @Transistor. I have a Raspberry Pi which controls a 12V addressable LED strip. When the data wire is ...
1
vote
3answers
85 views

Eliminate AC noise from DC supply?

I have built an automatic water tank using the circuit given below: But this circuit was working well for 2 days. But after that, it triggers falsely. When a fan in another room is switched on, this ...
1
vote
2answers
72 views

Design Considerations for comparator with ~1mV accuracy?

I am working on building an "exploded" analog to digital converter (ADC) (tracking type: up-down counting) for teaching purposes. I am working with a 0-5V reference, and 12-bits of precision (values ...
0
votes
2answers
59 views

How to insulate DC from earth noise while keeping it referenced to it

I have an AC/DC converter (220 to 24) inside an electrical cabinet. The 0VDC is referenced to earth, like this (couldn't find a symbol for an AC/DC converter in the schematic editor so I made a dirty ...
2
votes
1answer
69 views

Why does my Android phone charger cause my (powered-off) stereo receiver to make a high-pitched chirping sound when plugged into the same powerstrip? [closed]

After days of scouring my apartment, wondering if I’d developed another pitch of tinnitus, trying to figure out what the hell was making that infernal noise, I finally isolated it to this. Onkyo ...
0
votes
0answers
38 views

Allowing different inputs without needing to alter gain every time; a situation for a pre-amp?

The goal I am attempting to make a small diy bookshelf speaker system using 2 16ohm, 25 watt speakers and a 2x25 watt class d amplifier board. If it matters, the amplifier board is a class d amplifier....
0
votes
0answers
28 views

1V Overshoot and Undershoot on Power Rails of LTE Module

I have designed a PCB (four layer) having SIM7600I LTE Module. The Stackup is: Signal & Component Layer with Ground Pour Internal Ground Power Plane Internal ...