This is my first post and I joined this forum to elicit some help with a aggravating situation. There is a public address speaker in the shop. It has a 1000HZ annunciator signal that lasts for app. one second before the human speech announcement. This frequency must be designed to be the most offensive to the ear and I wish to eliminate it. I want to detect the 1000HZ tone to turn on a relay. My problem is I don't remember how to detect this and convert it to a DC to energize a relay to complete my timing circuit. There isn't any DC or AC on the speaker wires before the public address system is activated. Then there is a app. 1000HZ (may be 950HZ) that is at 16.5VAC. My Fluke meter is a little slow for the one second annunciator but that is the best I can read and my readings may be a little off. I thought about a band reject filter but 1000HZ is right in the middle of human speech so I just want to detect it to start the operation of my timing circuit. Thanks for any and all suggestions.