08-07-2014, 10:44 AM
SELF POWERED DOOR BELL WATCHER
SELF POWERED.ppt (Size: 22.5 KB / Downloads: 43)
INTRODUCTION:-
This is very simple & self powerded device was concived to allow a person to monitor if someone has rung his home door bell when he was out.
As most door bells use 12volt supply the circuit must be simple connected to the two door bell coil lead's.
WORKING:-
When the door bell is activated an AC voltage of about 10-16 volt is developed at , its leads so it is rectified by D1 & charges C1.
Through this device was primarily intended to be used when a person leave's the house , for a few hour or a week a no. of test has proven that a minimum 15 days memory can be granted even using cheap capacitor types.
To know if the door bell has rung you must simply push P1 if the even occurred led D2 will illuminate and will fade slowly to the off state in some second, this operation will reset the circuit also.
precautions:
If the circuit is connected to 230V mains some parts in circuit can be subjected to lethal potential. Avoid the circuit when plugged enclose it in a plastic box.