How to Make an Intercom From an Old Telephone

Written by contributing writer
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If you want to communicate with someone from one room or floor to another without shouting or using your cell phone, consider assembling and installing a wired intercom system. Your voice on the wired intercom will sound as clear on the other end as it would during a phone call. You won't have to purchase an expensive intercom system if you have unused old phones available. Instead, use a few electronic parts to convert those devices into a makeshift intercom.

Skill level:
Moderately Easy

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Things you need

  • Soldering gun
  • Solder
  • Phone wire
  • 680-ohm 1/2 W resistor
  • 12-volt battery gel cell
  • 2 Phone jacks
  • Wire stripper and cutter
  • Flat head screwdriver
  • Phillips head screwdriver

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  1. 1

    Wire the two phone jacks together, matching wire colour. Strip back about 1 inch of wire and screw on the jack, making sure to match wire colour. Green will go to red, and red to green on the other jack.

  2. 2

    Cut one of the wires in between them where you want to install the battery. It is not important on which colour you are cutting. Strip back the wires about 1 inch.

  3. 3

    Solder your 680-ohm 1/2 W resistor to one end of the wires you just cut. Attach the other end of the resistor to the positive terminal of the battery.

  4. 4

    Attach the other end of the cut wire to the negative of the battery. You should now be done and have a working intercom. You will need to charge the battery when needed with a charger specified for the battery type you have purchased.

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