Traces of Touch

serendipity into the oblivion

Posts Tagged ‘preamp

Phone detector

with one comment

I have just finished building together a “phone” detector. You all know the annoying sound that sometimes happens when you are about to get a call and the speakers make funky sounds. Taking advantage of this fact that  electret microphones easily pickups the radio waves of phones when calling I built together a small circuit to amplify the sound and make it readable to Arduino. Since I generally have a hard time to find a good working circuit I have supplied the list of the components below together with eagle files. It is heavily based on the Futurekit 648 Audio amplifier which you can find here. As you can see in the video below it starts reacting before the phone shows that a call is incoming because of the increase in radio activity.

Eagle files

Components needed:

C1       10uF
C2       10uF
C3       0.01uF
C4       33uF
C5       10uF
R1       15k
R2       27k
R3       18k
R4       2k
R5       1k5
T1       2SC945
U$1      MIC9.7MM

Written by sjunnesson

August 18, 2010 at 19:33

Posted in prototyping

Tagged with , ,