Hello everyone,

I'm building the circuit here: http://www.electronicsforu.com/efylinux/circuit/may2003/ci4-clap.pdf

I started building it without the mic and simulated a mic with a piece of wire (short circuit vs open circuit) - everything seems to work after a fix up of the Decade counter circuit.
I then bought several condenser mics and tried it with them, but I can't get a response if I clap (or any sort of response).
Currently this is one of the mics I have: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=102-1732-ND

The voltage drop across it is about 8V.

Does anyone have any suggestions as to what I should try? Another mic? Thanks in advance!

 

Are you sure you have the polarity correct?

 

Pretty sure. Red wire +, black is ground. I've tried switching them, but I didn't notice any response either.

 

Asuming the polarity IS correct, which would have been my first question too.

Try increesing the 3.3k, quite a bit I would expect, and reduce / remove the 4.7K to test.

Once you have a pulse, of some sort, on the transistor base add back seriese resistance before the cap to slow things down a little.

(I would be working by experimentation here due to lack of knolidge,
Sorry I cant be more spaciffic.)

 

The mike datasheet, link from your link, recomends 2V bias 'standard'.
It also states operating current of 500uA!!
You need to redesign the input stage, it will not be sensative enough as is, considder a buffer amp, freferably FET inputs. (Also see datasheet test circuit) should be simple with modern opamp or a FET perhaps?
Al