Detailed entries for one subject from the INDEX TO HOW TO DO IT INFORMATION.
Click on a see also (sa) or tracing (xx) to view detailed entries about a related subject.
The entries are in alphabetical order by magazine name and then in chronological sequence.
To obtain a copy of any magazine article contact your local public library or the publisher.

Phone Sentry tells you when an extension phone is already in use by flashing an LED. Est. cost: $5.
ELECTRONICS EXPERIMENTERS HANDBOOK 1993 pg. 14

The extension silencer. This project prevents interruptions by locking out extension phones when the line is in use.
ELECTRONICS HOBBYISTS HANDBOOK 1990 pg. 79

Phone-line privacy module. A specialized two-lead semiconductor (bilateral silicon trigger) installed on every telephone outlet will prevent the accidental interruption of a modem or fax connection.
ELECTRONICS NOW May 1996 (v.67#5) pg. 69

Phone line sentinel. Put an end to phone-call interruptions. This device monitors the phone line at each telephone and lights an LED to indicate if the line is in use. Est. cost: $15 (kit).
ELECTRONICS NOW Nov 1996 (v.67#11) pg. 53

Tip on installing the Northern Telecom 2960 network interface module in every telephone outlet box for use as an extension phone lockout.
ELECTRONICS NOW Jun 1997 (v.68#6) pg. 62

Phone-line privacy module. A specialized two-lead semiconductor (added in series with each phone that might interfere with modem operation) will protect your modem communications from accidental interruptions.
POPTRONIX EXPERIMENTER HANDBOOK Summer 1997 pg. 78

Phone-line-busy indicator circuit. An LED glows red or green depending upon whether an extension telephone is in use.
POPULAR ELECTRONICS [2] Nov 1990 (v.7#11) pg. 26

Isolating telephone extensions. How to use an extra pair of wires and a switch to incorporate an extension-silencing feature. This will eliminate eavesdropping or allow a fax or modem to operate without interruption.
POPULAR ELECTRONICS [2] Apr 1991 (v.8#4) pg. 41

Line-in-use indicator circuit monitors one or two phone lines from remote extensions.
POPULAR ELECTRONICS [2] Jul 1991 (v.8#7) pg. 22

Phone-in-use indicator also indicates the presence of a ring signal on an LED.
POPULAR ELECTRONICS [2] Sep 1992 (v.9#9) pg. 75

A telephone-line in-use indicator light.
POPULAR ELECTRONICS [2] Jan 1993 (v.10#1) pg. 43

Line in-use indicator circuit causes an LED to light whenever a phone is taken off hook.
POPULAR ELECTRONICS [2] Feb 1993 (v.10#2) pg. 73

Telephone circuits. (1) Circuit uses a light-dependent resistor to sense when a phone with a built-in flasher is ringing. (2) Two circuits will tell others when a telephone line is in use by lighting an LED. (3) Two circuits sense when a phone rings and activates a loud fire bell. (4) Extension ringer sounds a bell in a remote location.
POPULAR ELECTRONICS [2] Nov 1996 (v.13#11) pg. 64
Added Info POPULAR ELECTRONICS [2] Jan 1997 (v.14#1) pg. 6

Modem protector circuit completely disconnects all phones on a line when you are using a modem.
POPULAR ELECTRONICS [2] May 1997 (v.14#5) pg. 69

Modifying the Radio Shack Teleprotector (a device to prevent eavesdropping or interruption from an extension phone) to be more versatile.
RADIO-ELECTRONICS Jun 1991 (v.62#6) pg. 68

Phone Sentry indicates when a telephone extension is in use by lighting an LED.
RADIO-ELECTRONICS Sep 1991 (v.62#9) pg. 60

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