Questions tagged [noise]

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

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47 views

Absurd screeching from a buck convertor

I got a buck converter from Amazon. This- https://www.amazon.com/MCIGICM-step-down-Converter-3-0-40V-1-5-35V/dp/B06XZ1DKF2 Now it's soldered onto a custom PCB I designed. I'm supplying it with 12V and ...
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Noise that resets a device that I would like to avoid from chip reset pin

History/context: I talk about a 15Mhz noise when drill machine or any kind of machine activation in my network, before, at other post. By the moment neither RC, RL or RLC butterworth low pass filter ...
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45 views

Electric noise filtering seems not to have any effect over voltage input noise

I have designed two PCBs with slave SPI nodes at both. One of the two PCBs is connected to a Raspberry SPI port, it became the master node. This PCB also has a 74HC51 (suggested for i2c and spi lines ...
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90 views

Oscilloscope “noise”?

I'm just getting a start learning about electronics, and purchased a new oscilloscope -- a DreamSource Lab DScope U2P20 4, which uses the open-source DSView software 5. I built a simple 555 timer ...
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38 views

Low noise transistor series pass voltage regulator

I'm currently working on a series pass voltage regulator within LTSpice. Here is this circuit: I have read that these circuits are prone the oscillating and being unstable? This is one concern, the ...
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2answers
73 views

Isolating fan noise from analog circuit

I have a center tapped transformer (12-0-12) and a 24V fan, in order to get the required 24 V for the fan and also bypass the fan noise, I'm thinking of a circuit like this: simulate this circuit &...
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118 views

What causes flicker or 1/f noise?

What physical processes causes the generation of electrical and radio/EM/RF flicker or 1/f noise? Or why are those sources not generating normally distributed electrical observables (such as thermal ...
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39 views

Is this broadband noise calculation correct?

I came across the following paragraph from this application note: I didn't quite get where the formulas come from to calculate the amplified signal and the broadband noise. Why is signal noise not ...
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62 views

Does the bandwidth at the receiver really affects the noise in digital modulations?

I know that, in a telecommunicacion system, the AWGN power after going through the receiver filter is $$ P_z = KTB $$ where B is the bandwidth of the filter, T is the operating temperature of the ...
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276 views

Reduce noise on 2m I2C bus using motorcycle power

We would like to use an I2C bus with a cable length of 2m (unshielded twisted pair) on a motorcycle. The I2C bus connects an arduino to a sensor and is set to 10kHz (we have tried the common 100kHz ...
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106 views

What's the role of capacitors in this circuit?

This is a followup from a previous question: Analysing signal unbalancing stage which was quite broad as it encompassed couple of things, but answer there pointed me in the right directions so I'm ...
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1answer
81 views

Digital signal in my circuit is too noisy [closed]

I have a very simple digital circuit which I built with 74LS chips. Basically, the Q output of a JK flip flop is fed into a chip in another prototype board through a connector about 30 cm long (the ...
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48 views

How to select offset frequency for phase noise measurement?

When reviewing datasheets or papers on oscillators, phase noise is obviously an important parameter, but I see that the phase noise is highlighted at one offset frequency from the carrier in ...
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How can I get rid of the noise from this audio amplifier (using a Kemo M031N)?

I am trying to wire up an audio amplifier circuit using the Kemo M031N 3.5W amplifier: I have connected the wires from the amplifier to a terminal block. With a suitable 10V power supply and a 2W ...
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1answer
82 views

What “mode” is static electricity (lightning?) Is it common-mode, differential-mode? It seems half-way, or “mono”

The common-mode or differential-mode designations assume two conductors, one in-phase, the other anti-phase, but a static circuit is different because the "conductor" is concentrated in thin ...
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46 views

How to “clean” a DC brushed motor : noise on CANbus even without moving!

We have very odd problem with a DC brushed geared motor that we are driving with a classical H-bridge chopper (20kHz PWM at the moment). The motor kinda looks like a Mabuchi from an R/C car but with ...
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2answers
72 views

Schmitt trigger not working

I have a circuit like this: I am using a LT1719 for the Schmitt trigger. The Schmitt input signal is intended to be a 6 kHz waveform of 0.6 V pk-pk amplitude. When I test the Schmitt with an ...
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159 views

Both UPS and speaker end up having the same electrical hum, how come?

I have a speaker (Logitech Z623) which was driving me crazy with a low intermittent hum. In order to get to the root of the problem, I attempted multiple solutions. In the process I discovered that my ...
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29 views

How does flicker noise cause phase and amplitude noise in an oscillator?

It seems to me like the flicker noise is phase modulated with the output sinusoid in an oscillator, but why is this the case? I'm guessing that the amplitude noise is a result of the flicker noise ...
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84 views

Is excess noise in a resistor only present with DC?

Resistor excess noise is present when DC current flows in a discontinuous material, for example through carbon granules in a carbon composition resistor. My question is: Why there is no excess noise ...
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Does “a signal is buried in noise” mean that the noise amplitude is still smaller than the signal amplitude? (Special case: Lock-in amplification)

I heard that Lock-in amplifiers (LIAs) especially play to their strengths when the signals are weak compared to the noise level. But then I talked with someone about it, who understands the principles ...
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2answers
38 views

LTSpice noise simulation with custom noise voltage source

I'm trying to simulate noise of a circuit in LTSpice. I need to add custom white-noise voltage sources to the circuit, but when I do a noise simulation using the ".noise" command I don't see ...
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24 views

Literal white noise [migrated]

My friend has a work desktop computer with some non-fancy hardware. The onboard audio is output via a 3.5mm cable to some speakers in the room. These speakers produce a constant hum while the computer ...
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42 views

Trace Routing / Noise Question

I have a stackup like the following: Top GND Power Bottom I am routing a trace that I have discovered is especially sensitive to noise; for example, when working with the signal on a bread board, ...
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3answers
87 views

Audio Amplifier using an Op-Amp

I am experimenting with Op-amp for making a audio amplifier. I am using this circuit. I want to know if the values of C424 and C118 are correctly chosen here or do they need to be change? I hear ...
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1answer
96 views

Eliminate beeps and bleeps in the power lines

The platform is having various supply voltages generated by the power supply: +5V (for digital part), +12V and -12V for analog part, including video amplifiers. My device, which is being installed ...
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1answer
47 views

diode required for smoothing capacitor

I never quite understood the finer details of why a diode is required for turning capacitors into "smoothing" capacitors instead of just low pass filters. The simulations I have done in ...
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1answer
63 views

DAC Output Noise

I'm using DAC902 @ clock rate of 40 MSPS. The DAC is generating a 1 MHz sine wave. when I measure the output of the DAC, I get the following noisy sine wave: I'm not sure what's the reason behind ...
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1answer
46 views

Electret microphone and FET pre-amp

My question is about designing a microphone pre-amplifier that uses an electret microphone. I saw a video of Doug Ford on the EEVBlog, in which he shows some pre-amplifiers for microphones. My ...
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1answer
42 views

Multiple transformer windings vs a single winding with a buck converter for dual output power supply?

I have to create a power supply that has both a 5V output at 1A and a 3.3V output at 0.4A. I was wondering if I should add another winding to my transformer or just make a 5V 1.5A power supply, and ...
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62 views

HX711 noise, but only in a specific environment

I'm working on a small project at my farm to automate vegetable weighting. The system consists of an STM32 MCU, some additional ICs (matrix decoder, parallel-serial converter for some push-buttons etc....
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46 views

Mysterious noise of a CAMAC based digitizer

I'm trying to find out the cause of noise of a CAMAC based digitizer, which converts analog signal to digital signal. It basically functions as an ADC. The input of the digitizer is connected to a ...
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31 views

RC noise figure calculation

I would ask for some help with noise figure calculation for circuit attached. It is front end of improvised differential probe that I would like to build. I am aware that simulators such as LTSpice ...
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42 views

Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?

Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?, if other parameters such as output voltage, current, type of transformer core, ...
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41 views

How do I measure an 'industry standardised' noise given Vrms ~ oscilloscope settings?

I have an example of a noise source, but the specific device is unimportant to the fundamental aspect of this question. I'm trying to measure it's level with an industry standardised method so that I ...
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1answer
80 views

AC PWM noise generator design advice

I already tried to solve my LTspice problems within another thread here on the forum but I guess my design is bad. So for this reason I decided to start a new thread with some more information about ...
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1answer
18 views

Spectrum intensity varies depending on the frequency span

I am trying to measure the noise of a photo detector at different frequencies, using an RF spectrum analyzer. The measurement range was spanning from 10 Hz to 20 MHz. To cover not only the higher ...
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2answers
356 views

Oscilloscope probe noise

I am trying to measure a DC signal in the mV range. Below is the waveform I get after I connect the oscilloscope to its probe and without connecting it to anything: I am getting a ripple like ...
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59 views

Where exactly earth current flows-SMPS/DC-DC and DC-AC

Ashamed to ask this question after having lot of experience in Converter designs. i always heard and learnt from Sr. Mentors that For better EMI performance we need to give path for conducted noise(...
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1answer
62 views

Suitable op-amp and voltage regulator for 16-bit ADC

I would like to use the AD4008 16-bit ADC from Analog Devices to sample a load cell. I also need a linear regulator and driver amplifier and instrumentation amplifier. I am curious to know if these ...
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113 views

DC coupling - How can I reduce low frequency noise?

I'm using a precision 16-bit DAC (AD5689) to create DC bias current source, as indicated in the following picture and I'm detecting a high level of low frequency noise. I represented L1 as an ...
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34 views

Advantages and disadvantages of using igbt module with integrated rectifier bridge

What would be the main problems of using an igbt module with a rectifier bridge in an ac-ac converter project? Noise? Temperature? Does separating the rectifier bridge from the full bridge really ...
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38 views

Absolute values of fourier transform of noise-charged RLC circuit

I am doing time-domain simulations of currents in a parallel RLC circuit charged by thermal noise. In detail in pseudo-code: ...
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58 views

Need feedback for a PCB design (digital/analog synth)

Ok so I'm designing a synth using the NES sound chip (AY-3-8910). After poorly designing a PCB for it and testing it, I realized there is noise from the MIDI input bleeding to the audio output. I read ...
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39 views

What happens if the Ground plane is expanded/poured in the VCC/Power layer in the multilayered PCB design? Is that recommended?

I just wanted to know what are the advantage and disadvantage expanding the ground plane in the VCC/power plane in the multi layered PCB. Below is the 10 layered PCB stackup:- TOP, Gnd, Sig 1, Sig 2, ...
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1answer
58 views

Why the power line interference harmonics appear gaussian?

I have a recorded signal from a data acquisition system. I am getting this noise in my signal: The picture shows the FFT of the signal. I checked the frequencies of the noise and they are 50 Hz apart ...
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2answers
75 views

Only using ground fill on RF portion of PCB

I'm designing a 4-layer PCB that has RF components and digital components. I've decided to use a ground fill only on the portion of the PCB with RF components in order to increase isolation between ...
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1answer
90 views

Noise on the PWM signal. What value of capacitor should i add to decrease the noise?

I have noise on my 60Hz PWM output. The PWM output is going to the ESC to control the motor. Below is the signal with 5V per division. The PWM signal is a 60Hz, 10V signal. The duty cycle can be ...
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1answer
76 views

What does electrical noise that is mitigated by a human hand tell us about the noise itself?

I'm sorry if this is too vague, I'm not thinking of a specific instance when this happened. There have been at least several times when I've been debugging the source of some unwanted electrical noise ...
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31 views

Reduce switching noise on autotransformer

I am trying to achieve the same thing they are talking about in this post, which is controling an autotransformer via software. I accidently even got the exact same autotransformer, but instead of a ...

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