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Build a Ring Detector

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  • REPRINT
  • PORTLAND ATARI CLUB
  • SEPTEMBER 1985
  • AUTHOR: MIKE FULTON, A.C.A.O.C.

NOTE: BUILD AND USE AT YOUR OWN RISK

Those of you who frequent bulletin boards probably have noticed that more and more boards have been popping up. This activity is likely due to the fact that the necessary equipment to set up a BBS is becoming less and less expensive. Additionally, running a BBS is an easy way to meet others who share your interest in ATARI computers.

We consistently receive questions on how to build a ring detector for use with a BBS. A ring detector is a device that allows your computer to detect when the telephone is ringing. If the computer cannot detect the ring, it doesn’t know a caller is trying to access the system.

A ring detector is a very simple electronic device that is easy to build, requires only a few inexpensive parts available at most electronic stores, and provides reliable service with no maintenance. However, correct wiring is critical if you want to prevent any damage to your computer. If you are uncomfortable working with electronic parts, proceed very carefully with the following directions. The device you will end up with is not FCC approved and could damage your computer if not properly constructed.

PARTS LIST:

  • 22μF or greater capacitor (Radio Shack #272-1014 or equivalent)
  • 125 volt AC relay (Radio Shack #275-217 or equivalent)
  • Modular extension converter (Radio Shack #279-364 or equivalent)
  • Atari joystick replacement wire or equivalent
  • Small plastic enclosure

ELECTRONIC DIAGRAM:

This diagram appears to illustrate a specific electrical wiring setup involving multiple connections and unused wires, possibly for a technical or engineering application.

DIRECTIONS:

  1. Connect the red phone wire to the negative (-) side of the capacitor.
  2. Connect the green phone wire to pin number seven (7) on the relay.
  3. Connect the positive (+) side of the capacitor to pin number eight (8) of the relay.
  4. Use an ohm meter to determine which wires of the joystick replacement cable are connected to pin number six (6) and pin number eight (8) of the joystick plug.
  5. Connect the wire that leads to pin number six (6) on the joystick port to pin number three (3) of the relay.
  6. Connect the wire that leads to pin number eight (8) on the joystick port to pin number five (5) of the relay.
  7. Install all components into the small plastic enclosure so that only the phone and joystick wires extend out.
  8. You are now ready to plug the phone wire into the phone jack and the joystick plug into joystick port number two (2) on your Atari.