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Analog Noise Cancelling Headphones
Hi, It seems to be really good project, so I want to make it working well. I built it and what I saw is:- there is no need for using 500k potentiometer, 4,7k is enough to hear any changes- I can hear small noise cancelling effect (I'm using small earphones, so the distance from mic to earphone can be changed easily and doesn't matter at all)Advice if you have any suggestion what to do, to make this ANC effect working well. Maybe manipulation with C3, C4 and R4 to change phase shift? (I don't have osciloscope and I'm not a specialist, just an interesting hobby making circuits).PS. While tweaking the potentiometer, I hear the noise more from the earphone than environment, after more tweaking , I hear something like white noise, then big distortion finally. The circuit is powered by 2x9V batteries. It hasn't yet a good metal case.
how hard is this for a complete noob from 1 - 10?
Hello, would anyone help to understand where to connect the headphones on breadboard?
i have a doubt with your principle..Is the cancellation happening in atmosphere of ear. Or the cancellation is taking place within the circuit or electrically?
Thanks for posting this! Would it be at all possible to use a circuit like this to dampen noises created by loud products, such as vacuums and hand drills?I have looked into ANC and it seems it is easier to achieve if you have direct access to the source, eg. ANC speakers. So if you were to place surface transducers or speakers on the products producing the sound and have them as the outputs instead of headphones, and connect them to an ANC circuit and microphones to pick up the objects noise (which would also be placed on the object), would you be able to get the noise dampened? If so, could you use a circuit similar to this? Or is this scenario way too different to the one this post is about? Thanks for any feedback
Just about to finish it ... Can anyone help me whether the TL701cn op amps will work or not... Checking the datasheet of both (LT1056s and TL701s), found same config ... And also I'm having troubles finding the ECM-60PC-R Electret Mic ... Can anybody provide me the equivalent mic that should be suitable?
MattB34, thanks for your answer.However you link seems to be broken I cannot reach the paper. If you could send it again it would really help me.As a matter of fact, i'm trying to build my own noise cancelling circuit as part of a project for my competitive exams at the end of the year. As a consequence, I am interesting in understanding the maths behind this circuit (even if it means heavy tranfer functions). It would allow me to have a basis of comparison for my circuit.I've already put a lot of work in establishing the equations behind the circuit, and I would like to understand how the phase shift works.Thanks for your answers anyway ! :)
Hey MattB34, I wanted to build this circuit using a low voltage audio amp, primarily to use a supply of 9V only (no negative supply). Would LM386 work as a substitute? I understand I'll have to make modifications to the circuit. Could you point out where?
Here is the phase change i've found. The phase change without taking into account the distance between the microphone and the speakers inside the headset is in blue. In magenta this distance has been taken into account. Anyway, the phase changes and does not stay at +/- π... If someone has figured it out and can help me ^^Thanks !
Great work here ! Thanks !I'm trying to understand how the system works. I've drawn the Bode Diagrams of each part of the circuit, but the phase change never reaches π either -π... Could someone help me to understand how it works please ?Thanks ! :)
Great project, thanks for posting. I'm going to build this over the holidays. However, I noticed you are not using audio amplifiers for this but instrument amplifiers. Was this a conscious choice or just what you had 6 of in your tool box? Even the data sheet of the LT1055 is conspicuously lacking audio as a suitable use. Wouldn't something like a high-performance audio OpAmp like the OPA4134 be more suited for this project?
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