Indicators and Display


Circuit / Schematic diagram Description


Telephone line indicator (circuit on demand)


Indicated the status of telephone connected to a common line.

Telephone on/off hook indicator The circuit gives audio/visual indication of on/off hook and ringing modes.
Telephone in use indicator It will allow users to know if the phone is being used and not to pick up the phone.
Extension free indicator Indicates if another phone using the same line is free or not.
Telephone busy indicator Indicates if any telephone in the same line is busy or not
Caller Identification  
Caller Identification 2  
Caller Identification 3  
Telephone Billing machine Circuit can be used in PCO for displaying the actual call time.
Telephone call meter using calculator Displays the call time and based on simple calculator and COB
Smart Phone light The circuit shown here is used to switch on a lamp when the tele- phone rings
Talking phone dial monitor Detects the number pressed and speaks the dialed number
Telephone dial alarm Microcontroller based.
Telephone number display The given circuit, when connected in parallel to a telephone, displays the number dialled from the telephone set using the DTMF mode.
DTMF Tone Decoder Displays telephone numbers decoded from tones

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