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.

Circuit for a simple intercom which uses the LM380 audio power amplifier chip.
CQ. THE RADIO AMATEUR'S JOURNAL Sep 1979 (v.35#9) pg. 72

Tip: A non-electronic intercom is made by taping exposed litho film over a hole cut in a darkroom door or wall.
DARKROOM PHOTOGRAPHY Mar-Apr 1979 (v.1#1) pg. 14

Power pack for your telephone intercom.
ELECTRONICS ILLUSTRATED Jul 1964 (v.7#4) pg. 72

Switchless intercom allows two-way conversation just like a telephone. Est. cost: $30 to $35.
ELECTRONICS ILLUSTRATED Jan 1965 (v.8#1) pg. 41

TV "call box" allows TV sound to be interrupted and used as a loudspeaker for calling people watching TV.
ELECTRONICS ILLUSTRATED Jul 1965 (v.8#4) pg. 90

Transistorized intercom costing less than $7 per unit allows several stations with central battery power supply and audible signaling.
ELECTRONICS ILLUSTRATED Nov 1965 (v.8#6) pg. 79

Convert telephones into telephone intercoms where every unit is a master from which you can call every other unit. Est. cost: $5 per station.
ELECTRONICS ILLUSTRATED Mar 1966 (v.9#2) pg. 68

Intercom uses integrated-circuit amplifier.
ELECTRONICS ILLUSTRATED Sep 1969 (v.12#5) pg. 64

Intercom where each remote becomes a master station capable of calling any other station or answering the door.
ELECTRONICS ILLUSTRATED Nov 1970 (v.13#6) pg. 27

Home intercom. Master station monitors remote station full time. Uses one IC.
ELECTRONICS ILLUSTRATED Sep 1972 (v.15#5) pg. 34

Intercom circuit uses the LM380 op-amp (but can be adapted to other op-amps). A small 16-75 ohm speaker serves as both speaker and microphone.
ELECTRONICS NOW Feb 1997 (v.68#2) pg. 14
Added Info ELECTRONICS NOW May 1997 (v.68#5) pg. 62
Added Info ELECTRONICS NOW May 1998 (v.69#5) pg. 8

Descriptions of intercoms will help when building or buying an intercom.
ELEMENTARY ELECTRONICS #763 Winter 1965 pg. 67

Speaker-Fone. Can serve as a loudspeaking telephone receiver or a switchless intercom. Est. cost: $25.
ELEMENTARY ELECTRONICS Jul-Aug 1969 (v.8#3) pg. 39

Phone-Com intercom uses telephone handset to allow private conversation.
ELEMENTARY ELECTRONICS Mar-Apr 1970 (v.10#1) pg. 35

A complete amplifier, requiring only 9 volts, is small enough to cement on the back of the magnet of a small speaker. Response will be flat from 100 to 20,000 KHz. Uses an integrated circuit power amplifier. Can be used in an intercom.
ELEMENTARY ELECTRONICS Nov-Dec 1970 (v.10#5) pg. 41

Install switch-selectable remote speakers around your house and yard in order to monitor CB, act as an intercom or provide entertainment.
ELEMENTARY ELECTRONICS Sep-Oct 1976 (v.16#5) pg. 78

How to install a combination AM-FM radio/intercom system in the home. Gives tips on cable connections, between-wall wiring and surface mountings.
FAMILY HANDYMAN #178 Feb 1977 (v.27#1) pg. 50

Tip on cleaning the volume control on older in-the-wall intercom systems.
FAMILY HANDYMAN #388 May 1998 (v.48#5) pg. 16

Intercom circuit uses two separate amplifiers, instead of a single amplifier and a time-sharing scheme, allowing longer runs between stations.
HANDS-ON ELECTRONICS May 1987 (v.4#5) pg. 95

Two-wheel communicator. Self-contained, battery-powered portable electronic intercom for use between two riders on a motorcycle. Incorporates voice actuated circuitry to reduce wind noise.
HANDS-ON ELECTRONICS Apr 1988 (v.5#4) pg. 43

Hands-off intercom. Switchless intercom offers all the convenience of a face-to-face conversation. Requires a two-wire interconnecting cable. When either unit is turned on, then both are operational.
HANDS-ON ELECTRONICS Nov 1988 (v.5#11) pg. 39

Tip: How to convert cheap telephones into an intercom system.
HOMEOWNER May 1986 (v.11#4) pg. 22

How to install an intercom system for your house. Installation shown includes three door speakers and nine remote speakers.
HOMEOWNERS HOW TO Mar-Apr 1979 (v.4#2) pg. 42

How to install a cab-to-camper intercom for a pick-up camper using the Heathkit master and remote station kit. Easy kit can be assembled by beginner in about 4 hours. Est. cost (kit): $26.
MECHANIX ILLUSTRATED #536 Jan 1973 (v.69) pg. 50

How to install a combination radio/intercom/burglar alarm system. Est. cost: $250.
MECHANIX ILLUSTRATED #546 Nov 1973 (v.69) pg. 130

Low-cost wireless intercom transmits over house wiring. Est. cost: $25 per station.
MECHANIX ILLUSTRATED #550 Mar 1974 (v.70) pg. 38

Connect two telephones to make a private two-station intercom. Two circuits shown. One allows you to ring the other phone.
MODERN ELECTRONICS [1] Jul 1978 (v.1#5) pg. 32

Convert two telephone handsets, a switch and some twin-lead antenna wire into a simple intercom or a toy telephone system.
MOTHER EARTH NEWS #84 Nov-Dec 1983 pg. 186

How walls have ears. Using a scanner to eavesdrop on wireless intercoms, baby monitors, and similar low-power FM devices.
POPULAR COMMUNICATIONS Jan 1990 (v.8#5) pg. 29

Three-transistor transformerless intercom circuit.
POPULAR ELECTRONICS [1] May 1965 (v.22#5) pg. 76

Circuit for a four-transistor intercom.
POPULAR ELECTRONICS [1] Sep 1965 (v.23#3) pg. 79

Intercom doubles as a burglar or fire alarm.
POPULAR ELECTRONICS [1] Oct 1966 (v.25#4) pg. 97

Simple circuit addition to a wired intercom turns on a lamp (LED) when audio signal is being received. Useful for high noise areas.
POPULAR ELECTRONICS [1] Jan 1972 (v.1#1) pg. 101

Circuit allows the use of a loudspeaker as a microphone in an intercom circuit.
POPULAR ELECTRONICS [1] Apr 1973 (v.3#4) pg. 100

Circuit for a two-station intercom that uses small speakers for both microphones and output speakers.
POPULAR ELECTRONICS [1] Aug 1975 (v.8#2) pg. 81

The LM380 power amplifier integrated circuit. Has a very low output impedance and can be directly connected to an 8-ohm speaker. Can operate up to 3.7 watts with heat sink. Circuits for amplifier, intercom and phase-shift oscillator shown.
POPULAR ELECTRONICS [1] Sep 1976 (v.10#3) pg. 121

Build a DTMF (dual-tone multi-frequency decoder) field telephone that operates over two wires. Powered by a 6-volt battery. Ideal for communicating between tents at a scout camp, on a construction site, etc.
POPULAR ELECTRONICS [2] Feb 1989 (v.6#2) pg. 41
Correction POPULAR ELECTRONICS [2] Apr 1989 (v.6#4) pg. 4

Two-way com-link amplifier circuit forms the basis of a two-station intercom system. A spring-return switch is used to toggle between talk and listen modes.
POPULAR ELECTRONICS [2] Oct 1990 (v.7#10) pg. 80

Adding a loud horn to an intercom system. This modified annunciator is ideal for a noisy environment.
POPULAR ELECTRONICS [2] Jul 1991 (v.8#7) pg. 21

Op-amp based circuits. (1) One-way voice-activated intercom. (2) Analog audio-frequency meter. (3) Simple audio-power amplifier.
POPULAR ELECTRONICS [2] Apr 1992 (v.9#4) pg. 67

Switchless (duplex) intercom system lets each party break into a conversation at any time. Communications and power are delivered over three connecting wires.
POPULAR ELECTRONICS [2] Sep 1997 (v.14#9) pg. 75

Schematic for a simple intercom system which can monitor or converse with another location.
POPULAR ELECTRONICS [2] Jan 1998 (v.15#1) pg. 67
Correction POPULAR ELECTRONICS [2] Mar 1998 (v.15#3) pg. 5
Correction POPULAR ELECTRONICS [2] Apr 1998 (v.15#4) pg. 56

Make surplus phones into an intercom system.
POPULAR MECHANICS Feb 1963 (v.119#2) pg. 142

Convert an old telephone into a CB transmitter for use as an intercom.
POPULAR MECHANICS Sep 1966 (v.126#3) pg. 166

Wireless intercoms that plug into a wall outlet are described.
POPULAR MECHANICS Jul 1969 (v.132#1) pg. 130

Simple battery-powered intercom system featuring master and remote stations which transmit up to 100 ft. over two-conductor wire.
POPULAR SCIENCE Aug 1966 (v.189#2) pg. 102

Its easy to build electronic projects with prewired modules. Put these high-gain amplifier modules to work in (1) an intercom, (2) an audio signal tracer, and (3) a stereo amplifier.
POPULAR SCIENCE Oct 1967 (v.191#4) pg. 140

Home intercom system has a simple amplifier in each station and uses 2-conductor cable throughout the system. Uses a push-to-talk button on each station.
RADIO-ELECTRONICS Jul 1980 (v.51#7) pg. 63

Intercom modifications, including converting a speaker to function as microphone, adding multiple inputs, switching, etc.
RADIO-ELECTRONICS Sep 1984 (v.55#9) pg. 82

Build this nine-station intercom for a home or business. Uses standard pulse-dial telephones and has options for a public address system with background music. Simple control center provides a switchboard-like function allowing any one of nine phones to call any other. Est. cost: $50.
RADIO-ELECTRONICS Jan 1987 (v.58#1) pg. 57, 67

Tips on installing intercoms.
RADIO-TV EXPERIMENTER #772 Feb-Mar 1966 (v.20#1) pg. 71

Modify a 9-volt battery-powered transistorized intercom to use a 12-volt battery and install the intercom between pickup truck cab and camper. Est. cost: $12.
RADIO-TV EXPERIMENTER Jun-Jul 1967 (v.22#3) pg. 75

Circuit for using one audio amplifier in an intercom unit consisting of two speakers, local and remote.
RADIO-TV EXPERIMENTER Dec 1968-Jan 1969 (v.25#3) pg. 34

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