Questions tagged [noise]

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

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684 views

What is the impact of a pass transistor on power supply noise?

I am designing an ultra-low noise 5V power supply for a DAC in an audiophile hi-fi application. I would like to get the noise floor below 5uV lower. I am looking to use a TPS7A4700 LDO which has a ...
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30 views

Noisy power supply

I recently purchased a Meanwell 5V 5A (25W) single output power supply. This power supply is connected to a load that draws a total of 2.3A. The load consists of an esp32 dev board, sim800l, and two ...
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64 views

Arduino freezes due to: power supply?

This is going to be a long question but I don't want to leave any loose ends. I'm developing an incubator which includes a hot air pump to conduct heated air through a hose to a closed chamber (~100 ...
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72 views

Why does customer see high voltage on my PNP sensor output?

I have designed a capacitive sensor with a PNP output. The output stage is a Sziklai pair, as follows: simulate this circuit – Schematic created using CircuitLab While the circuit works OK, one ...
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1answer
50 views

Where do we place a Pi filter?

I have used pi filters in the past with the USB powers and it worked great. This time I need the pi filters to smooth out the 24V supply from a regular SMPS power adapter. There is a load switch/fuse ...
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54 views

Noise in an unconnected biopotential electrode lead wire

My question stems from a particular statement on page 256 of the textbook Medical Instrumentation - Application and Design, Fourth Edition (by J. Webster): Relatively high potentials can often be ...
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96 views

Make audio signal go only one direction

I have a circuit in my car which emulates the protocol the radio uses to communicate with a CD changer. The goal of the emulator is basically to make the radio open up it's audio channels. The circuit ...
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2answers
59 views

What is the maximum length a MC68030 can be placed away from Commodore CDTV motherboard, without affecting timings?

I want to fit a TF536 accelerator card into Commodore CDTV case, which is a challenge from the perspective of available space. I know there is a relocator board project available, but it still doesn'...
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43 views

“Noise” in simulator

I have been working on a simple circuit which performs XOR operation. The problem is that I am seeing a noise-like graph when both inputs are set to 1 (5V) and I have been doing a research on what it ...
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45 views

Capacitive AC to DC power supply noise

Im using a transformerless capacitive power supply with this simple circuit: C1: 3.3uF 400V R1: 480K D1-D4: 1N4007 Z1: 10V 1W C2: 470uF But it burned some my ...
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46 views

Filtering out Switching Noise

I'm designing a custom current limiting circuit designed for electric bikes and small electric vehicles. It's purpose is to limit battery current to "dumb" motor controllers so that you can ...
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134 views

Noise in audio amplifier

I have built an audio amplifier using TDA2030. The amplifier works fine with very low noise, the input is given through 3.5mm jack of my phone. Everything works fine until I touch or pick up my metal ...
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140 views

“To ground” or “not to ground” a coax to prevent RF ingress?

I have a communications system that connects a self-powered sensor circuit to a wall-powered processing/analyzing circuit by coax cable The coax reaches out about 60m, and it is matched/terminated at ...
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1answer
70 views

esp8266 power supply problem

It's the fourth esp8266-12e that destroyed with my AMS1117-3.3 voltage regulator. I'm powering esp8266 with AMS1117-3.3 module and this simple circuit: ...
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54 views

I need help with making a ground loop noise isolator

I want to build a ground loop noise noise isolator for 3.5 mm audio jack. After some research online I found multiple circuit diagrams centered around using audio 1:1 transformers to isolate each ...
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Is Gaussian noise equal to white noise?

If noise on a signal is randomly fluctuating in time domain around its mean following a Gaussian normal distribution (Gaussian noise), would this be equivalent to an constant intensity in the ...
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51 views

Speaker and player on same 5V charger crackles but not with two separate chargers

I am using a Samsung mobile phone connected to an external speaker (connected via a standard audio cable with jack connectors). Audio is playing fine when I use two Samsung-branded 5V-DC chargers, ...
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2answers
79 views

What is the origin of multiplicative noise from a DSLR sensor?

I'm trying to understand the behavior of my DSLR camera sensor (Canon 80D). I've taken a picture of a gradient from top-right to bottom-left corners of a square. This square is positioned at the right-...
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85 views

Ultra low noise charge sensitive preamplifier

I developing charge sensitive preamplifier for radiation detector. This is a very sensitive device, the smallest amount of noise can completely ruin the signal. The schematic and the PCB you can see ...
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3answers
83 views

Is there a limit to the number of inputs that can be summed with an op-amp summing circuit?

I'm interested in the limits you encounter if you try to add many inputs into an op amp summing circuit. I've read that the inverting configuration is more natural for adding many inputs since the ...
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20 views

Bluetooth Receiver Board - Noise Problem

I recently bought a bluetooth receiver board in order to add bluetooth to my car, this however is not as easy as I thought. I am not very skilled with electronics. I have an aux audio input in my car ...
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1answer
35 views

How to prevent switching direct and/or inductive noise on a PCB?

I'm designing a power source for one of my projects and I couldn't find a better way to reduce the voltage drop on 7805 regulator other than using a switching regulator (LM2596). The switching ...
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1answer
29 views

Power interference when turning on speakers, causing monitor to go black

I have a small 2.1 external speaker system that I use with my laptop. I also have an external monitor that I use with the same laptop. Almost every time I turn on or off the speakers, the external ...
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44 views

Analog differential signaling

I'm a software engineer that sometimes has to deal with some electronics. So I'm by no means an expert... I want to control a BLDC motor and I have added a thermistor to the windings of the motor so ...
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2answers
66 views

How can picked up FM noise be demodulated?

I have a set of cheap computer speakers, which happens to use a TDA2822M. Its circuit is almost identical to the example circuit from TDA2822M's datasheet. It's USB powered and has no shielding. I ...
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1answer
81 views

Noise with TPA3110D2 amplifier on the same power supply as an USB HUB

I have a TPA3110D2-based, XH-A232 amplifier board powered by a 12V switching supply (S-120W-12V). The input is the headphone output of a monitor connected to a PC. I would like to power an USB HUB ...
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2answers
64 views

How can thermal electrical noise be uncorrelated yet appearing at a certain frequency?

Say we look at the thermal noise spectrum of an ideal resistor. Now we know it will behave like $$ \langle U^2 \rangle = 4 \, k_B \, T \,R \,\Delta f $$ We also know that two subsequent voltages ...
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57 views

Audio: Digital Potentiometer is Noisy Compared to Analog Potentiometer

I am building an A/V switch that I would like to have a headphone output with adjustable volume, controlled by a microcontroller. As a test, I connected an audio source to a potentiometer (input to a, ...
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45 views

Power rail noise calculation

I am attempting to calculate the noise on the power rail that my ADC is receiving so I can calculate my effective number of bits. But the different units on the datasheets of the regulators are ...
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49 views

NPN condensor mic pre-amp really noisy

I have designed a pre-amp and I am having a lot of noise when silent. It seems to be around 70 Hz on my scope, but jumps around. I've tried adding bypass filters on the NPN emitter legs, as well as ...
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17 views

Noise Temperature to Noise Factor

If I have a noise temperature of (I'm not sure how to do subscripts) Te = T1 + T2/g1 and since Te = (fn-1)To. I believe that fs = f1 + (f2-1)/g1 But I'm not sure what the steps in between these 2 ...
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95 views

How to get rid of 19kHz electrical fields

The mains of my German flat has 19kHz electrical fields on hot, neutral and! ground wire. I don't have to get rid of them entirely but I want to achieve 20dB reduction while sitting in front of my ...
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1answer
35 views

Op-amp noise figure

If I have an opamp such as LM324 or a voltage regulator. How can I obtain noise figure experimentally? For the opamp I would apply DC input and the ratio of output SNR to input SNR would be noise ...
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67 views

WS2815 noises problem

I've been trying to use WS2815 leds in my stairs, but I'm struggling with noises problem. I'm using stm32f103c8t6 based bluepill board as a controller for 18 1m long led strips. Each strip is ...
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1answer
47 views

Reduce signal noise detected by accelerometer due to interference from a motor (caused by reverse neutral current)

EDIT AND IMPROVED QUESTION: After working at it, I figured that the problem was that my DAQ is reading the current that flows back into the DAQ through the neutral wire. My DAQ is powered with DC ...
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31 views

1/sqrt(f) low pass filter slope [duplicate]

I would like to emulate a 1/f noise source in PSPICE. If I use the EVALUE component in the Analog Behavioral Models library, and use the function RND()-0.5, I have a zero-centered white noise source. ...
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253 views

What are the effects we need to consider when transmitting extra low voltage (0.1 uV) signal over ~1m long cable?

What are the effects we need to consider when transmitting extra low voltage (0.1 uV) signal over about 1 meter of cable, either coaxial or shielded twisted pair ? The source is low impedance (~5 ...
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3answers
46 views

Signal to noise in relationship with limit of detection and/or signal strength

I wonder about the following: The limit of detection is given as being 3 sigma of the blank peak away from the blank signal (which is noise finally, I think?). What struggles me is: In my head this is ...
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37 views

Regarding signal to noise ratio

I had set up multiple receivers and I was recording the same signal on all of them. I then stacked all of these signals. I have read that to improve the signal to noise ratio, mean and median of this ...
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1answer
35 views

Problem with custom USB microphone

I developed a MEMS microphone based audio capturing device and transfer that audio via USB to the PC. I used Audacity opensource software to test my working and found the audio plays well when ...
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5answers
115 views

What is the opposite of the Power Supply Rejection Ratio?

The PSRR of a device is the dB measurement of the power supply noise rejection. In my case, I have an LP5907 LDO with a PSRR of ~80dB, which would mean that if I have 10dBm of powerline noise on the ...
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1answer
43 views

ngspice simulation : random signal source

I'm new at the ngspice simulator and I don't understand this line of a Netlist that I found Vn 1 n1 dc 0V ac 1mV trrandom(1 5us 0s 125m 0m) if the random signal ...
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1answer
81 views

What is the purpose of this PLC circuit?

I am reverse engineering the PLC I/O module. One output consists of a Smart Switch with 3 additional components. Obviously, this is some kind of protection. But how does it work? Updated: PCB ...
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2answers
37 views

Assumptions in the Calculation of Noise Vrms

I was doing some reading on noise analysis and its calculations. The SRS lock in amplifier specifies input noise levels only at a certain frequency and not the entire spectrum itself. For example: \...
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98 views

Where does Differential noise come from in a switching power supply

I would like to know where does differential noise come from in an SMPS. I understand where the common mode noise comes from. It mainly comes from the fact that there is capacitance between switching ...
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3answers
39 views

Demodulation/filtering of a binary signal

I'm simulating an amplitude modulation system on Matlab and have got to filtering the demodulated system. The original data to be sent was a 1x100 set of binary data. Which was then applied to a ...
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2answers
48 views

Calculating power emitted from electronics

I am trying to figure out how much "thermal noise" electronics may produce as I am trying to detect the cosmic microwave background radiation, but the electronics surrounding the detector will ...
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3answers
63 views

Can you reduce audio noise by decreasing input impedance with a resistive load?

First asked this over at sound stackexchange but they pointed me over here as a better place for it. A general question but inspired by a specific example so framed as such. I have powered studio ...
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3answers
1k views

Why single ended signal line is not immune to noise in RS232?

In single ended signal line the measurement is the difference between the signal and the ground. Isn't this way of calculation make it differential? Almost all the resource I have read says that ...
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48 views

Tl494 converter powerend kind of oscillation / buzzing

I'm in trouble with designing and testing tl494 halfbridge converter (schematic based on atx power supply and this one: https://www.hobbyelektro.eu/spinany-zdroj-0-30v-0-6a/) Converter wasnt quite ...

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