Telephone related electronic circuits

This project is aimed to make the low cost intercom system by which eight telephone lines can be interfaced with this hardware.... [read]

This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing... [read]

When the circuit detects that a phone line has been cut, it activates a MOSFET which can be used to drive a relay, motor, etc. It can also be connected to... [read]

Extremely easy to build and very useful transmitter... [read]

Have you ever been using the modem or fax and someone else picks up the phone, breaking the connection? Well, this simple circuit should put an end to that.... [read]

This circuit will allow you to place a phone call on hold and if you wish to have them listen to music while they are on hold.... [read]

Makes your 220/110V bulb flashes when telephone rings. Can be very useful when you need silence, or just want to have strange phone :)... [read]

This circuit is extremely simple, therefore there is less chance of any problems. It can be placed anywhere on the phone line and it will record any conversation... [read]

The normal telephone bell, at times (specially during night when one does not want to be disturbed), appears to be quite irritating. The circuit shown here... [read]

While talking to a distant subscriber on telephone, quite often we feel frustrated when the voice of the distant subscriber is so faint that it is barely intelligible.... [read]

Audio from a telephone line can be obtained using a transformer and capacitor to isolate the line from external equipment. A non-polarized capacitor is placed... [read]

Although a hold feature is standard on most new phones, a lot of us still use the origional bell phones. Those of us that require a hold feature will find... [read]

Telephone In-Use Relay Controller circuit diagram... [read]

This nifty little circuit lets you record your phone conversations automatically... [read]