Duel tone multi frequency (DTMF) electronic circuits, schematics or diagrams. Discovercircuits.com is your portal to free electronic circuits links.
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1 GLOLAB Universal Telephone Hold UNIVERSAL HOLD CIRCUIT If you have touch tone telephone service, you can now put a call on hold from any phone in the house, [. . ]
Electronic circuits for Telephone applications like status indicator, transmitter circuit, Telephone operated remote etc.
Just hook this Alarm Phone Dialer up to something you would like to monitor, for example, a high water alarm, low temperature alarm, back window, garage door, etc. When the system is activated it will call a number of programmed numbers to let you know the alarm has been activated.This would be great to get alerts of alarm conditions from your home when you are at work. The microcontroller code is provided on the site........