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Carbon Microphone
http://www.diyaudioprojects.com/Forum/viewtopic.php?f=12&t=6705
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Author:  BowToEd [ 23 Jan 2020, 01:37 ]
Post subject:  Carbon Microphone

This is something I thought up a few weeks ago. Since they were making carbon mics by hand a hundred years ago, I figure it might be time to try my hand at it.

I'll start by turning two wood shapes on my lathe. They'll be rings but have flanges that nest (if that makes any sense). Then I'll screw them together with thin aluminum wedged in between. The flanges should cause the aluminum to stretch tight.

I bought some activated charcoal from an aquarium store. If I pulverize the granules to smaller bits, and possibly heat them to remove volatile chemicals, it's possible I can increase their conductivity.

If I can do the above, and if I can manage to craft a cup to hold the grains against the diaphragm, I should have a microphone. I'll have to run some current through them and use a transformer to recover the sound.

The hardest part will be machining all of the parts.

Ed

Author:  Woodo [ 29 Jan 2020, 17:36 ]
Post subject:  Re: Carbon Microphone

good luck with the R and D Ed. hope you have success! i was looking at whether there are inexpensive mikes to measure my speaker frequency v spl etc using REW and noticed your post.

Author:  gofar99 [ 29 Jan 2020, 21:40 ]
Post subject:  Re: Carbon Microphone

Hi, Yes good luck, The voltage needed as I recall is fairly small and you might start out with a "D" cell or two. A matching transformer and coupling cap are probably required as well. The resulting audio (if any) could be fed into a standard mic preamp. It is just possible that a mic preamp designed for a condenser mic might work as it has a built in dc supply. Possibly too much voltage though as the seem to run in the 20-40 V range.

Good listening
Bruce

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