Originally posted by oldtimetech:
Remember LOUD Klaxon horns?
Yes of course we had a Klaxon in the fire station on the single line phone (emergency RED Line). That one must have been connected to the tip/ring from the CO since we did not have a key system (KSU) at the fire station. (Acutally the fire stations preferred to have a bank of single line phones with neon ring lamps, no KSU to deal with if the power was out).
Speaking of the fire station (this was in the the 1970's), they had this wacky signaling system on the RED line for the fire alarm. The RED phones had an exclusion key in the hook. With the phone off hook, you pull up the exclusion key, and push this external button (which sent tip to ground). This would close several can relays also connected to the line in parallel (thoughout the town where the alarm sirens were located). Sending tip to ground would cause the CO to ring the line and close the can relays to set off the fire alarm. The only catch was that only one RED phone could be off hook or else the line would not ring.
The part I never figured out was what kept the can relays from closing when the RED line would ring normally for an incoming call? I'm guessing the can relays were connected ring to ground?
