[Coco] Telephone System

johnmarkmelanie at gmail.com johnmarkmelanie at gmail.com
Sun Apr 28 07:43:34 EDT 2024


All,

How to make a simple analog phone system:
https://www.youtube.com/watch?v=8bwLjU90puA
Note 1: The resistor is unnecessary if the telephone devices are in series.
Note 2: With a 300-ohm resistor and both phones off the hook the system
draws about 5 mA and the audio is softer.
Note 3: Without a resistor and both phones off hook the system draws about 9
mA and the audio is louder.
Note 4: If you hang up one or more phones then the system draws about 0.0
mA.
Note 5: A 100-ohm resistor might be a good idea to protect against a short
circuit.
Note 6: If the battery and the two phones are in parallel then put a
resistor in series with the battery.
Note 7: The polarity of the battery does not matter.
Note 8: There is no dial tone, dialing, or ring, just talk.
Note 9: You can test this at home before the show. 

Please consider bringing something to the show to hook up to the phone
system.

-John Mark Mobley




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