Questions tagged [acoustic-noise]

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Low-frequency load drive stage design considerations

simulate this circuit – Schematic created using CircuitLab The circuit above is used to control a 240W ceramic heater by means of a PWM signal, generated by a microcontroller, with 5V logic. The ...
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2 votes
2 answers
249 views

How do I deal with acoustic noise from a transformer under PWM load?

I am working on a hobby project involving controlling LED strips (working at 12 volt and drawing up to 5A). The light intensity of the strip is controlled using a single MOSFET transistor (...
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Acoustic noise from EMI filter

I am using this proportional valve driving circuit: The valve is 24V, 2W, driven with a 2kHz PWM. I hear an acoustic noise coming from the EMI-Filters L49, L77. I know that the noise is coming from ...
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4 answers
338 views

Soft start circuit design for audio amplifier

I have a 100W D class amplifier that runs on 24V. It uses 2 x TPA3116D2 IC for amplification. I also have a 24V 16A power supply. I need to provide a soft start circuit for this, because the amplifier ...
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1 answer
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What is meant by this dB description?

I come across such descriptions as below when I read about "90 dB SPL with 1 watt, measured at 1 meter distance" or "Sound pressure level of 90 dB 1 W/1 m". Another example is: &...
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How do you model acoustic waves underwater that are generated by an Nd:YAG laser?

In this paper on page 84 they show the following experimental setup: The array of receiver hydrophones are set up to record sound pressure waves sent by the transmitter hydrophones. In Figure 6....
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1 vote
0 answers
399 views

What to check for hissing noise in a LCD monitor and how to reduce it?

I have a Dell LCD (LED backlight) without speakers which produces an audible "hiss" when connected the HDMI input. DisplayPort much less. I have recorded the following spectra: monitor off (this is ...
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2 votes
5 answers
2k views

MC34063 based converter accoustic noise

I am trying to make nixie clock and I use MC34063 for buck/boost converters. The nixie tubes require 180 V to operate and the microcontroller and LEDs need 5 V. I use external 20 V power supply as a ...
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4 votes
3 answers
770 views

How is that "howling" sound produced in induction motors?

Note: No, there are no inverters involved in this question here. I've perceived that most, if not all induction motors make a "howling" sound in their coils that is different from the constant 60 Hz ...
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1 answer
63 views

Bad background noise in audio capture [closed]

I have a microphone attached to a Realtek ALC5640. The circuitry is as below: L9 is Murata BLM15PD121SN1D The noise capture is here. How could I improve the situation and reduce this noise, if ...
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2 answers
43 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 ...
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using a vibration / noise sensor as edge finder in a CNC machine

I have a desktop CNC machine which has just the basic functionalities like controlling the speeds and position with a somewhat reasonable accuracy / precision. I also have an edge finder which I can ...
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2 answers
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Circuit Choices for AmpIifier Input

i have breadboarded a TDA2050 amplifier, using this schematic i get good sound intensity with a half acceptable quality. the down side is the constant noise and humming. i have found a possible ...
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4 answers
1k views

How to remove noise from microphone input?

The Issue I've made a project centred around the XS3868 module which is based on OVC3860. The circuit works fine and I was able to get the microphone to work except for just one thing, the mic input ...
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1 answer
160 views

Clarity on dB SPL calculation

Based on this post, let me assume that I have a input source of 94 dB SPL / 1 Pa that a microphone is picking sounds from. The microphone has a sensitivity of -46dBV/Pa , this gives 0.005012 V RMS/ ...
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1 answer
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Detection of Acoustic signals

There is a scenario: There is a certain box which emits acoustic signals at 30kHz and you are trying to detect these signals using some sort of detector. I was wondering, would it be more efficient ...
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1 answer
130 views

I have an outlet adapter that is clicking at 260bpm. What is happening? [closed]

I plugged this adapter, GE Grounded Adapter-Spaced Six-Outlet Tap, into my outlet the other day. I noticed a clicking noise in my apartment, and it's coming from the adaptor. I used an online app to ...
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2 votes
2 answers
482 views

Is it possible to generate different PWM Signals for same duty cycles(e.g. 50%)?

Let us expect we have a duty cycle of 50%. Is it possible to reach that duty cycle with different PWM Signals (waveform)? With different I mean variants in the number and lengths of the "active time". ...
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1 vote
1 answer
337 views

High pitch sound coming from Low-Dropout Linear Regulator (1117 3.3V) setup

I am using the below schematic to drop voltage from 5V to 3.3V (1117 3.3V - http://www.farnell.com/datasheets/2100276.pdf?_ga=2.141255921.210515873.1532314816-790306462.1508240417) for a Wifi Micro-...
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-2 votes
1 answer
124 views

Switch a line level audio signal - which chip is best WRT noise, low loss? [closed]

I am relatively unexperienced with audio circuits, and need to switch a standard line level signal, AC, about 6Vpp. I have the chips listed below, and would very much appreciate some pointers as to ...
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-1 votes
3 answers
731 views

How to control the brightness of an AC light bulb with the instant level of noise nearby

The device I want to make is simple to describe: a big red lightbulb, connected to the AC 110 / 220 V, stays dark when it's quiet in the room, starts lighting up somewhat if there's a moderate level ...
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3 votes
3 answers
172 views

What device/component from the early 1940's can listen to only a specific narrow range of acoustic frequencies?

This website briefly describes the development of the first active acoustic homing torpedo of the US Navy: Investigation of the use of echo-ranging equipment or an "active" homing torpedo ...
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8 votes
2 answers
230 views

Is the maximum audible noise from power supplies regulated in Europe?

Power supplies make sometimes a lot noise in the range of kHz. Is there a regulation for the maximum allowed noise emission for consumer electronics on the European market? Is there a regulation ...
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1 vote
0 answers
407 views

Audible Ticking in Audio Opamp Circuit

I'm experimenting yet again with the following audio mixing circuit: On the scope with signal gen as source, everything looks great. When hooked up to the input of a mixer with a laptop as the source,...
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0 votes
1 answer
78 views

Troubleshooting Noise/Quirks in Audio Circuit

I am working on a project that takes in a single line-level audio channel and outputs 2 balanced/unbalanced +/- outputs from that channel. I have read a number of the excellent published articles ...
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1 answer
308 views

What can cause a very low frequency sound from a laptop? [duplicate]

I have a Clevo M57RU laptop here. Whenever it goes to stand-by, sleep or is shut down I hear a VLF sound (presumably close to the ~20 kHz maximum of the human ear) that's even better to hear if the ...
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1 vote
1 answer
1k views

Buzzing power supply

I have a power supply that buzzes when nothing is connected and is silent when there is a power drain. What could it be? It's a PC power supply that I used to power an LCD through its 12 V line.
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3 votes
3 answers
632 views

Why do wall plug power supplies use audible switching frequencies?

Every plug-in power supply ("wall wart") I have ever used starts off silent, but eventually starts to emit high frequency switching noise. It usually happens only when the charger is on, but not ...
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5 votes
1 answer
4k views

Audible noise in DC-DC buck converter

In my design, I have a +3.3 V SMPS that provides power to digital circuits (microcontroller, EEPROM, etc.). The microcontroller allows applying a 100 Hz PWM signal with variable duty cycle and with an ...
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