i’ve assembled the mk103 and can’t get any output from it. if i jumper T3 or T4, the led’s light up fine. i thought perhaps i gave the mic too much heat soldering it in, so i removed it and gave the board a constant signal from the output of an mp3 player with no results. is it possible that i overheated T1 or T2 when i soldered them in as i did not think to use a clip on heatsink.
i also have a question about a modification i would like to try.
i would like to replace the mic with a piezo element and mount it on a small board with 8 led’s wired in pairs then in series. they are 3,500 mcd / 2.0V @ 20 mA. the distance from the main board would be about 2 meters via 4 conductor solid core copper phone cable. the use for this is so i can mount the led’s and piezo inside a drum and keep the main board isolated in a case with more mk103’s, one for each drum with different colored led’s.
is the bc557 a suitable replacement for the bc547 as my local store is out of bc547?
BC557 is NOT a replacement of the BC547, it is the exact opposite of the BC547 !
Check you assembly carefully. Most likely, an assembly error is at the cause of troubles.
If you can provide links to HIGH-RES and SHARP pics of both component and solderside, we can take a look at your assembly.
This forum does not allow upload, use a free picture base instead.
