Roff
Well-Known Member
OK, here's the schematic. It has been simulated, but not built and tested. The gain range is huge. Let me know if the range needs to be reduced, or if the gain is too low (which I doubt). I drew options for a 2-wire or 3-wire electret mic. Radio Shack has both types on their web site, with little information on how to use them, and I have little experience with them. If anyone sees a problem, pipe up!
I put a little flat spot on the top of the bandpass filter (BPF) response to accommodate component tolerances and frequency drift from the nominally 2kHz source. This is the reason the twp BPF sections have different capacitor values. If I were building this, I would not relax the component tolerances, because it might mistune the BPF to the point where the sensitivity is impaired.
If you want to use something besides LEDs as your indicator, or you need more of them, or more current through them, etc., post your wishes.
Please let us know how this works if you build it.
Ron
I put a little flat spot on the top of the bandpass filter (BPF) response to accommodate component tolerances and frequency drift from the nominally 2kHz source. This is the reason the twp BPF sections have different capacitor values. If I were building this, I would not relax the component tolerances, because it might mistune the BPF to the point where the sensitivity is impaired.
If you want to use something besides LEDs as your indicator, or you need more of them, or more current through them, etc., post your wishes.
Please let us know how this works if you build it.
Ron