need help electronic/relay problem phone horn

[georgebaker]

I need to ring a phone that activates a loud ass horn. Phone has no audio ports. I'd be tapping into the 2 wires that connect from phone circuit board to the phone ring speaker.

Inside the handset, the 2 wires show .035-.045 VAC (probed with multimeter while the phone "rings") and connect to an 8 Ohm 2W speaker inside the phone. This 8 Ohm 2W speaker needs to be replaced with a very loud horn or buzzer.

-I purchased a generic 12VDC piezo horn. Need to feed it 12VDC when phone rings. That's all.

I'm stumped. Low signal relay? Some type of inline amp? I can solder a bit, and have only  a very basic understanding of this stuff.

Do I look for a low signal relay? like .03VAC to 12VDC?

Thank you

[madires]

Welcome to the forum! You'll find tons of circuits when searching for 'telephone ring detector'. There are also kits and COTS modules. Some telcos sell them too, especially for hearing impaired people.

[Terry Bites]

https://circuits-diy.com/telephone-ring-detector-using-pc817-optocoupler/  or just about any opto, small signal npn or mosfet here.
Always use an isolater, ringing current can give you a painful shock.
Make sure the relay contacts can handle the DC load current- use a car hooter relay.
https://www.ebay.co.uk/itm/151808536651?hash=item23587e704b:g:cpQAAOSw3YZclOdo

[NiHaoMike]

All the ring detector circuits I have seen are for the old analog lines that have become uncommon many years ago. Pretty much every wired phone nowadays is VoIP. I would check the manual for the phone and the website of the manufacturer, it's a common problem for shop phones so most likely there's an off the shelf solution for it.