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Telephone related electronic circuits

Telephone circuit diagrams, phone bugs, custom ring tone... Make your phone glows when someone calls you and similar.

8 Line Intercommunication using 89c51

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

Cellular Phone calling Detector

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]

Cut Phone Line Detector

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]

FM Telephone Bug

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

Phone Busy Indicator

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]

Phone Hold With Music

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]

Ringing Phone Light Flasher

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]

Ringing Phone Light Flasher

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]

Soft Musical Telephone Ringer

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]

Telephone amplifier

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]

Telephone Audio Interface

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]

Telephone Hold Button

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

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

Telephone line monitor

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