samy555
Full Member level 4

Hello all
In this circuit:
from: http://stab-iitb.org/wiki/Mobile_Bug
I worked some calculations like:
I didn't understand why the designer made the (R1*C4) time very large (220 seconds), that is it take the DC voltage at pin #3 of CA3130 IC a 220 sec to increase from 0 volt to 0.522 volt?
Can you please explain to me the benefit of that.
thanks
In this circuit:

from: http://stab-iitb.org/wiki/Mobile_Bug
I worked some calculations like:

I didn't understand why the designer made the (R1*C4) time very large (220 seconds), that is it take the DC voltage at pin #3 of CA3130 IC a 220 sec to increase from 0 volt to 0.522 volt?
Can you please explain to me the benefit of that.
thanks