N1NKM's Optical Ribbon Mic |
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microphone! |
(UPDATED: 1/5/2007)
| Solar cell & preamp module |
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Top view of solar cell/preamp module. Note quarter for scale. This is the "active" part of the opical ribbon system. This is the next step of development, inspired by the "Hot air microphone".
| Solar cell & preamp module |
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This is the bottom (foil) view of the solar cell/preamp module. The solar cell is visible at the top. I mounted it by creating a small "pool" of solder, then dropping the cell onto it, and keeping it hot until it attached solidly. The wire connecting to the top electrodes is a single strand from a stranded wire. It's very delicate work to attach it and not destroy the very thin electrode foils!
The copper traces were made with a Dremel tool cutting disc and a very gentle touch. :) This is why they are all straight lines. With the engraving bit, curved traces can be made easily. There was no need to do that, here. Plus, the cutting disk is much faster & easier.
| LED module |
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Here is the LED module. (This is not actually a blue LED, it is a high-brightness near-infrared LED from a number of years ago.) In the dark, you can just barely see the deep red light output. I noticed a fair amount of hiss in the LED light... was it the LED? The solar cell? Transistor? I don't know.
| Protype OPTICAL ribbon mic! |
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Here is the working prototype! The audio output is rather low, so I will definitely be doing some more experimenting! As you can see, the ribbon was snipped out of a snack food bag. You can still read some of the nutritional information. ;) The case is the cover from a dead "wall wart". I think the ribbon is too close to the LED and photocell. I suspect that the audio is low due to the reflection being so short.
| Optical ribbon mic schematic |
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Here's the WORKING schematic! As shown in the pics, above, the LED and the photocell/preamp are on seperate mini modules. The physical arrangement of these modules and the mylar material are going to be experimented with for optimal performance. The LED requires its own resistor and bypass cap, to ensure that it sees only pure DC.
By holding the mylar ribbon in my hand and speaking very close to it, there is a very good output from the preamp unit! It's already showing considerable promise! But I eventually gave up tinkering with it, so progress was stopped at that point. Go ahead and try your hand at it! You may have better results!
| Optical ribbon mic with Gamma unit ribbon mic |
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If you wish to contact me, it's N1NKM2 (at) aol (dot) com
(Yes, the 2 is part of the address.)