Optical Theremin - Photocell Question

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SUMMARY

The discussion focuses on building an Optical Theremin using CdS (Cadmium Sulfide) photocells, which are effective light-dependent resistors. These photocells exhibit a resistance range from high-kOhm in darkness to a few ohms in bright light, making them suitable for this project. The user clarifies that while phototransistors and photodiodes may be alternatives, they do not provide the same range of resistance levels as CdS cells. The goal is to construct the Theremin while gaining a better understanding of the circuit involved.

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  • Understanding of basic electronic components, specifically resistors
  • Familiarity with circuit design and assembly
  • Knowledge of light-dependent resistors (LDRs) and their characteristics
  • Basic soldering skills for assembling electronic circuits
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  • Research the specifications and applications of CdS photocells
  • Learn about circuit design principles for audio synthesis
  • Explore the differences between phototransistors, photodiodes, and CdS cells
  • Investigate additional components needed for building an Optical Theremin
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Electronics enthusiasts, DIY hobbyists, and anyone interested in building audio synthesis devices or learning about light-sensitive components in circuit design.

k_squared
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I was endeavouring to build the (almost, at least) Theremin on this page:
http://www.popsci.com/diy/article/2008-04/build-pocket-theremin-cheap

However, I was wondering what kind of resistance the photocells should have. I suppose I could work up a better abstract understanding of the circuit and make an educated guess - which would be my ultimate goal - however, I would like the build it first.

Oh, and thanks for any response!
 
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Pretty much any CdS cell will work. These range from the high-kOhm to the low MOhm range in total darkness to a few ohms in bright light.
 
They are often sold now as "light dependent resistors" too. Same thing, new name.

They are not the same as phototransistors or photodiodes though. These may work but will not have the range of resistance levels that a CdS cell will have.
 

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