Hi, everyone!
I saw this circuit in the Tech FAQ
OFFICIAL Agent 04 Generic Test Set Modification (tm)
Ring >---------------------------------> to "test set" phone Tip >------! SPST Switch !-------->
!-----/ ----------!
from !-------/!/!/!/!--! C = 0.22 uF 200 WVDC Mylar
cable pair ! C R ! R = 10 kOhm 1/2 W (alligators) !--! (------------! SPST = Talk / Monitor
Has my somewhat outdated electronics experience failed me, or is there still a path for DC current even with the switch open?
With that in mind, I changed the schematic to:
Ring >---------------------------------> to "test set" phone Tip >------! SPST Switch !-------->
!-----/ ----------!
from ! ! C = 0.22 uF 200 VDC Mylar
cable pair ! C R ! R = 10 kOhm 1/2 W (alligators) !--! (--/!/!/!/!--! SPST = Talk / Monitor
Would the few mA of AC passed to the hybrid in the phone, as the author claims, be sufficient to produce a signal at the earpiece of an average phone? In my (admittedly lazy and highly unscientific) test, I got no output at all at the earpiece with 22nF and 10kR, although I didn't get the opportunity to try a higher value capacitor or proper fault diagnosis.
I was hoping someone out there in Usenet-land had tried this and might be able to advise before I commit to an afternoon of soldering and cussing :)
Thanks,
Neil