Telephone off-hook indicator

  
Inside:
Repository
The circuit depicted here can be used as an indicator when the telephone receiver is off-hook. The circuit can be in corporated with old telephones that does not have such an indicator. The circuit uses a complementary darling to pair using Q1 (2N3904)and Q2 (2n3906) to sense whether the receiver is off hook and glows a LED to show the condition.
Telephone off-hook indicator - schematic




Leave Comment

characters left:

New Circuits

.