You only have one telephone in your house, but you can't hear the phone from every room in your home? You want to be alerted whenever there's an incoming call, but if you can't hear the phone, what can you do?
This is the schematic for a circuit that will connect directly to your telephone line and produce an audible sound and flashing LED whenever there is an incoming call. Now, you will obviously need to have a phone jack wherever you want to use this circuit, but you won't need to have a telephone to hear the phone ringing - How cool. Take out the audio component and this would make for a very nice silent ringer, which would be super useful if you're running a radio station and don't want the studio phone ringing in the background when the DJ is on-air.
There are a total of 8 electronic components, with the main integrated circuit (IC) being the BA8204 or ML8204 (8-pin mini DIP package).
This circuit shows full component values and tips for modifying the circuit in various different way. Enjoy!