Is a Low Pass Filter Suitable for a Basic Noise Filtering Circuit?

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Discussion Overview

The discussion revolves around the suitability of a low pass filter for a basic noise filtering circuit in the context of building a laser listener project. Participants explore the components needed for the project, including the potential use of a low pass filter and the type of photocell suitable for audio applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses interest in building a laser listener circuit and suggests that a low pass filter might be necessary for noise filtering.
  • Another participant strongly advises against the project, questioning the feasibility of using a cadmium sulfide (CDS) cell for audio due to its slow response time.
  • A later reply confirms the slow response time of a cheap CDS cell, suggesting that it would not be effective for audio applications.
  • Alternatives are proposed, such as using a high-speed photodiode, but this would require a redesign of the circuit.
  • One participant mentions that a proper laser Doppler vibrometer (LDV) would work for the intended purpose but notes that it is likely beyond the budget of the original poster.

Areas of Agreement / Disagreement

Participants generally disagree on the feasibility of the proposed project, with some expressing skepticism about the components suggested, particularly the CDS cell, while others propose alternatives without reaching a consensus on the best approach.

Contextual Notes

Limitations include the dependence on the specific characteristics of the CDS cell and the potential need for circuit redesign if a different type of photocell is used. The discussion does not resolve the effectiveness of the proposed solutions.

ice109
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i want to build one of these

http://funditor.110mb.com/LaserListener.html

but he alludes to some kind of circuit at the end that could filter out the noise using analog components and I'm thinking it's some kind of low pass filter. am i right? i really only have a little electronics knowledge? i guess i need something called a preamp too? note I'm not malicious or anything i just think it would be a fun little project.

basically i want it to be portable cause i don't have a laptop
 
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Don't bother. I can't believe the author has actually built that. A CDS cell (cadmium sulfide) does not have a fast enough response time to actually be useful with audio.
 
Averagesupernova said:
Don't bother. I can't believe the author has actually built that. A CDS cell (cadmium sulfide) does not have a fast enough response time to actually be useful with audio.

:( really ? that's exactly the kind of photocell i bought, what kind can i use?
 
A cheap CDS cell has a response time of the order of 0.1sec so you are not going to get much audio out of it.

You could use a high speed photodiode, but you would have to redesign the rest of the circuit, and the whole idea looks a bit far fetched to me.

You use a proper laser doppler vibrometer (LDV) - that would work, but not in your price range!
 

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