Schematic of the door opening alert circuit.
Automatic door alarm circuit.
S1 and s2 are the two switches that are used in the circuit so that both can be put in two different places i e.
The door opening alarm circuit or front office visitor alert is used for alerting you when a customer is at your office shop.
A door opening alarm circuit is an indicator or a security alert device which activates while opening the device attached door.
One of them can put in front of the locker while another one can be placed on the front door.
Ne555 is wired as an astable multivibrator whose reset pin 4 is controlled by the sensor output.
When the door is closed the magnet is close to the sensor.
We will use a knife switch in conjunction with a 10kω resistor the 2 of these components form a voltage divider circuit.
Working of security alarm circuit.
Door alarm circuit circuit.
The 9 volts that are supplied to this circuit are in parallel with the 10kω resistor and the knife switch with the gate of the scr being.
Presence of north polarity magnetic field generates a low voltage at the output of the sensor.
For sensing the door position different types of methods can be used such as magnetic light beam mechanical electrical etc.
The schematic for the door alarm circuit is shown below.
And the alarm remains on as long as the door is kept open.
Door open alarm circuit.