RANDOM ACTS OF KAOS
Linemen set plans
----------------------------------------------------- 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
When SPST is closed, you are in talk mode; when you lift the switch- hook on the "test set" phone, you will get a dial tone as if you were a standard extension of the line you are on. You will be able to dial out and receive calls. When the SPST is opened, the resistor and capacitor are no longer shunted, and they become part of the telephone circuit. When you lift the switch hook on the test set, you will not receive dial tone, due to the fact that the cap blocks DC, and the resistor passes less than 4 mA nominally (far below the amount necessary to saturate the supervisory ferrod on ESS or close the line relay on any other switch). However, you will be able to silently monitor all audio on the line. The cap reactance + the phone's impedance insure that you won't cut the signal too much on the phone line, which might cause a noticeable change (..expedite the shock force, SOMEONE'S ON MY LINE!!). It's also good to have a VOM handy when working outside to rapidly check for active lines or supervision states.
Techni Tool - 5 Apollo Road, Box 368. Plymouth Meeting, PA. 19462. Specialized Products Company - 2117 W. Walnut Hill Lane, Irving, TX. 75229.
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I am not going to include a disclaimer, because a true communications hobbyist does not abuse nor does he tamper with something he doesn't understand. This article is intended as a reference guide for responsible people.
