Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [acoustic-noise]

32 questions
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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 which would protect customers who buy an alarm clock,…
Jonas Stein
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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 amplitude of +24 V to a resistive load. This is…
johsey
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3 answers

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 tone they produce due to the working…
user2934303
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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 (specifically FDA8440) connected to the MCU. I am controlling…
Zah
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3 answers

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 system was initiated under the auspices of NDRC in 1941 at…
DrZ214
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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 charging anything. I presume it is due to the…
Timmmm
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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 source. Here are the circuits: 5V 180V When the…
George
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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". What are the expected impacts on noise and…
user3352632
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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 input is a standard 280W AC-DC external power…
Francesco
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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 the filters, because when I short them, I do not…
G. B.
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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 about the minimum the phone can record, so it's not…
FarO
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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 solution for the problem to be the input, as when i…
Hamed Temsah
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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-controller and after few weeks of usage it started…
Zac
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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, I get the following audio noise (recorded with…
User7251
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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.
Leonardo
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