Questions tagged [noise]

Noise is an unwanted disturbance in an electrical signal. This tag is for questions about sources of noise, noise types, issues caused by electrical noise, or improving the signal-to-noise ratio of an analog circuit.

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2 votes
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Why the induced noise is sometimes additive but sometimes works as a constant?

Why sometimes the noise (e.g., induced 50hz hum) is added to a useful signal (thus increasing its 50hz value), but sometimes it works as a noise floor - has a static value and can be overpowered by a ...
0 votes
0 answers
72 views

What causes this noise on a PCB when the 2.4GHz antenna sends a packet? [closed]

I am using a 2.4GHz SMD antenna in my project. I am facing a lot of voltage jumping on my ADC (Intan Rhs2116) when sending a packet of data via the 2.4GHz antenna. The waveform looks like this. The ...
1 vote
2 answers
202 views

Trying to record from DIY op-amp results in seldom pops and clicks

I have a 741-based audio amplifier PCB here from the 70s: When I tried to test it, I powered it with a 24V battery (I tried 12V as well with no difference,) then I shorted pins 15-19, connected the ...
0 votes
0 answers
52 views

SGP30 supply issue in long wire i²c communication

I designed a module which integrates 3 sensors: SGP30, SHT20 and SPS30. All off them communicates to a gateway using i²c 100kHz and works fine when I use a 1.5m Cat5e UTP cable. However, when I ...
0 votes
2 answers
47 views

Ferrite bead on a SMPS output [closed]

Suppose I have an instrument which needs a very clean power supply line. I have an SMPS which outputs 24 V at 3.2 A, which is then cleaned via a LM1084 linear regulator. Given that the output of a ...
0 votes
0 answers
36 views

Microcontroller lockup when used near AC transformer [closed]

Context I have an electrical enclosure on an ex-industrial machine. The original controller and HMI (Human Management Interface) died. As a result I designed a new controller for the machine. I am ...
3 votes
2 answers
178 views

SDRAM logic makes noise on ADC readings with FPGA

I am working on a design in which an FGPA reads the output of a 12-bit 40MHz ADC and then stores half of the data on an external SDRAM and the other half on an on-chip BRAM after some averaging. The ...
-1 votes
2 answers
2k views

SNR and attenuation question

I have the question above from random material and I tried to solve it. Here, I assume signal power to be S1(dB) and noise power to be N1(dB) at input, and S2(dB) and N2(dB) at output. So below is ...
1 vote
0 answers
25 views

Speaker pop / crackle when SBC connects to WiFi

I'm using a Raspberry Pico to detect movement and play a sound via an amp & speaker. At certain intervals the Pico attempts to connect via WiFi to send and receive data. However, when attempting ...
0 votes
1 answer
587 views

How is this 50Hz noise coupled to the sensor and why does it disappear when wired in a particular way?

I'm using this amplifier with this load cell. There is a section in the amplifier's manual which states: First of all above terminal 5 in the amplifier's screw terminal which is called Screen/Ground ...
0 votes
4 answers
326 views

Can bussed grounds in an audio patchbay create a ground loop?

I am working on a project to create a patchbay-style interface for guitar pedals, wherein a set of guitar pedals can be routed in different configurations using TT cables (like the patchbay interfaces ...
1 vote
0 answers
193 views

HLW8032 energy meter circuit showing power usage at no load

I am designing an AC energy metering circuit. The circuit has to measure voltage, current, power, power factor and energy used for two channels (from the same source). The HLW8032 transmits 24 bytes ...
0 votes
1 answer
281 views

Phase-modulated Noise

If you replace the carrier signal in a phase modulated circuit with noise then presumably the noise will be modulated. What must be considered if we wish to detect this noise modulation? I’ve ...
1 vote
0 answers
122 views

Problem of noisy ground 2

I am new to the forum and am facing the exact problem as described by @gregoiregentil over 10 years ago. I am using the same setup as in the linked question. I have a circuit board controlling the DC ...
0 votes
1 answer
47 views

How to read ripple and noise on a linear power supply using RIGOL DS1202Z-e?

I am new and want to learn the right way to read noise and ripple from a linear power supply. In this case, I measured 5 V DC for a sample. I used 1 channel. I connected the center of the probe to +5 ...
11 votes
3 answers
1k views

Lots of electrical noise at boost converter output

I'm trying to implement a boost converter using TI's TPS55340. After spinning up the design, I have found that the output ripple is almost 8x what I expected to see given my design parameters. First, ...
1 vote
1 answer
78 views

What is the safest and most noise free grounding method floating or non-floating for audio plugs & circuits on 2U aluminum case and SMPS

I have read countless documents and viewed schematics on this subject but am still confused when it comes to physically building a box and running all of the wires correctly and safely. I drew a very ...
0 votes
0 answers
30 views

Optimal Op-amp circuit for sounder

I'm working on a 40kHz sounder. One pole of the piezoelectric transducer is connected to R3, other pole is connected to GND. OPAMP_OUT goes to STM32 ADC input. Is this op-amp circuit good enough for ...
0 votes
1 answer
208 views

Spark plug noise on power supply

I am working on a motorcycle diagnostic tool. Everything works fine except for the fact that when the engine is turned on, in some motorcycles spikes start appearing all over the circuit, and the ...
0 votes
1 answer
63 views

Noise in DC supply due to AC track nearby

The RL_NC track in the image will carry 230V AC. Will the EMI noise from this track affect my 9V supply nearby (output of LM7809)? I use the 9V supply to measure the voltage drop across a conducting ...
1 vote
1 answer
116 views

Unstable to do resistance measurements due to electric fans

I built a small system to monitor wood drying. The idea is to turn on exhaust or circulation fans (230V-AC) based on the absolute humidity and ambient temperature (respectively) of a small drying ...
0 votes
3 answers
217 views

Having multiple ground connections

When and where should grounds be connected togheter? I am currently in the process of designing a product as a hobby project. And i find myself getting stuck with (probably) a rather simple question. ...
0 votes
0 answers
34 views

Audio noise when Bluetooth is connected

I'm making a Bluetooth speaker with a rechargeable Li-po battery. I had some noise coming from the speaker that I suppressed connecting a capacitor at the Bluetooth board's power source. Apparently I'...
21 votes
8 answers
32k views

Reduction of DC motor noise

I am designing a circuit with a DC motor 12V DC Reversible Gearhead Motors - 70RPM and some other stuff including a MCU and a LASER, all driven from a single 12V source and am concerned about big HF ...
4 votes
1 answer
77 views

Unknown signal source

Using my oscilloscope near my TV(a Panasonic TH-L42U20A) seems to introduce an unidentifiable source of noise. The scope probe is floating, neither probe or ground clip is connected to anything, ...
1 vote
1 answer
2k views

How do I know to choose a first order filter vs a second order filter?

I have a DC signal coming off of a battery. The Arduino is reading the voltage. The issue is that the voltage signal contains a lot of noise (120hz frequency). I am planning on building a first order ...
1 vote
2 answers
215 views

Derivation of attenuator noise factor as a function of its physical temperature

I have been struggling for the past few days with the noise analysis of an attenuator of attenuation \$l\$, at a temperature \$T_A\$, connected to a source with input noise temperature \$T_0\neq T_A\$....
2 votes
1 answer
612 views

What's the noise figure of an attenuator not at room temperature?

I'm confused by the following: What's the noise figure of an attenuator with 10 dB loss at very high temperature, having a noise power of like 80 dBm/Hz? How about if the attenuator at very low ...
0 votes
0 answers
57 views

Stepper motor noise

I’m currently developing a belt drive system that uses two separate Nema 42 stepper motors and an htd pulley. Everything is working well except I recently increased the supply voltage from 110 to 220 (...
0 votes
2 answers
95 views

LM318 strange oscillations

I want to make a 100~200 kHz square wave signal. I tried with a Schmitt trigger oscillator . The circuit below worked well with another op amp but the slew rate was too low so a tried with the LM318 ...
0 votes
3 answers
463 views

Electrical noise on Wemos D1 Mini

There is an electrical humming sound coming from a Wemos D1 Mini v2 module. I'm using a 5 V, 3 A power supply connected to a 5 V input pin. I suspect it's the current input which causes the sparking/...
0 votes
0 answers
22 views

Control noise in circuit to avoid disturbance in flow sensor reading

I am controlling water pump and electro magnetic flow sensor ( YF-S201 ) by esp32. Flow meter affect while pump running. I disconnected flow sensor in my circuit for testing. While pump start to ...
0 votes
1 answer
65 views

USB Audio interface 50Hz + harmonics noise when either laptop or speakers are plugged in

As soon as I plug in either my laptop or my speakers to the wall, I get an unbearable amount of noise in my guitar recording. Signal chain: Guitar --(1/4 jack)-> Audio Interface --(USB)-> PC --(...
0 votes
1 answer
43 views

How do I handle +5V noise and PSU undervoltage due to an OLED module in my circuit?

I am working on a circuit that will use the ADC on an Arduino (Adafruit Feather M4 Express) to measure a small signal, so I want a minimum of noise. Testing the Arduino on a breadboard with a DC test ...
1 vote
1 answer
237 views

How to fix noise from speaker when using wall power supply (but works with a battery)

I'm trying to build a simple audio amplifier for an 8 Ω speaker. The schematic/design is from here (Wayback Machine link just in case that link breaks). I used a different transistor as I happened to ...
0 votes
0 answers
51 views

Software averaging filter for ADC readings in a boost converter application

I'm working on a boost converter using a microcontroller (STM32G030), and I need to measure input and voltages of the converter. But, due to switching noise, the ADC readings become noisy and cause ...
-1 votes
1 answer
202 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 ...
1 vote
1 answer
53 views

Will this electric guitar wiring scheme be noisy?

I want to wire my guitar using two SPDT switches for my pickup selector. This is so I can have four sounds: lower, upper, both in parallel, both in series. I'm concerned that when it's set to use ...
3 votes
1 answer
369 views

Spikes in acceleration data

I am trying to quantify the noise of the accelerometer inside the Parrot AR Drone 2.0, but the signal contains odd spikes. I simply placed the drone on a table and recorded the acceleration for about ...
0 votes
1 answer
74 views

Powering a NEMA17 stepper motor (DRV8825 driver) with a mt3608 boost converter

I'm encountering a very strange problem at the moment. In the course of my school project I need to drive a NEMA17 stepper motor with a DRV8825 stepper driver, which is soldered with its breakout on ...
1 vote
3 answers
663 views

What does nV/√Hz mean in the context of signal resolution?

From what I have read so far, V/√Hz is an expression for the amount of noise in a bandwidth. However, I came across a paper where they mention the minimum resolution of a signal required in the design ...
1 vote
1 answer
294 views

Noise due to stray voltages in a data acquisition system

A single ended earth grounded data-acq. board on the left in the below illustration has inputs coupled by BNC cables coming from force transducer amplifiers A1, A2, A3, A4 as shown on the right: If ...
0 votes
2 answers
108 views

Noise issue when powering several audio devices from the same power source

I'm working on my portable music production setup and I'm having noise issues due to connecting all my gear to the same power source. I have three devices (a sampler, a keyboard/synthesizer and a ...
7 votes
4 answers
1k 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 ...
-1 votes
1 answer
279 views

RF Matching Net

I am projecting a system that contains two RF chips, a LoRa SX1276 (915MHz) chip and a ESP32-D0WDQ6 (2.5GHz). In the schematic bellow, the ESP32 (2.4GHz) design has a matching net between the chip ...
10 votes
7 answers
2k views

If RF signals require matched impedance to remove reflections, why do approaches to shunt noise need only a “good path to ground?”

From my understanding, for signals to propagate without reflection the impedance of the path must be constant and can be shown via the telegraph equation. When it comes to noise on the line, for ...
0 votes
0 answers
17 views

Why different noise terms are read at specific sampling interval in Allan Variance plot?

I was trying to identify Quantization Noise, Angle Random Walk, Bias Instability, and Rate Random Walk from Allan Variance plot which as Allan deviation on y axis and Sampling Time Interval ...
0 votes
1 answer
102 views

Does a single input differential amplifier remove noise?

It is known that the purpose of using a differential amplifier is to remove noise from the input signal, apart from giving some small amplification. To my knowledge, there are two inputs and two ...
0 votes
0 answers
116 views

What is the purpose of these two capacitors?

I came across the schematic shown below. What is the purpose of C22 to C25? Unless they are used for differential noise, since FL1 eliminates the common mode noise present.
-1 votes
3 answers
2k views

Reduced gain with ground loop isolation with car aux head unit

How to suppress ground loop hum without reducing audio gain? I added an aux input to my car's factory head unit by soldering wires onto pin 4 (right channel) and pin 33 (left channel) of the M62490FP ...

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