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How did Phone Line control work?
Posted: Tue Feb 19, 2019 11:28 pm
by Screamer105
I know that sirens now mainly use DTMF tones for activation. But from what I heard, sirens back in the 70s and 80s used phone line control. Now, I have really no knowledge when it comes to any form of Dial-Up or any line control in general. Could someone explain to me phone line control was operated? I’m really curious.
Re: How did Phone Line control work?
Posted: Wed Feb 20, 2019 2:11 am
by siren fan
Good question. I still see sirens today hooked up to telephone poles, but not many.
Re: How did Phone Line control work?
Posted: Wed Feb 20, 2019 3:08 pm
by Brendan W
Here is some info on the CDWS, which was a phone line activation system commonly used in the days before FSK and all that. This info is from Bell Telephone Co, dated 1968. Hopefully this helps you some:
http://etler.com/docs/BSP/981/981-281-100.pdf
Re: How did Phone Line control work?
Posted: Wed Feb 20, 2019 8:32 pm
by FSThunderboltfan1000
Re: How did Phone Line control work?
Posted: Mon Mar 18, 2019 12:41 am
by MaineCivilDefense
A telephone controllable relay was used. If the number that the device was assigned to was called, the relay would switch, setting off the siren.