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.
Automatic door alarm circuit.
It will produce a beep sound when each new customer or visitor is entering and will automatically switch off after few seconds.
Presence of north polarity magnetic field generates a low voltage at the output of the sensor.
Pull pin security alarm circuit.
And the alarm remains on as long as the door is kept open.
The schematic for the door alarm circuit is shown below.
When the door is closed the magnet is close to the sensor.
Door open alarm circuit.
We will use a knife switch in conjunction with a 10kω resistor the 2 of these components form a voltage divider circuit.
The door opening alarm circuit or front office visitor alert is used for alerting you when a customer is at your office shop.
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.
One of them can put in front of the locker while another one can be placed on the front door.
A door opening alarm circuit is an indicator or a security alert device which activates while opening the device attached door.
Door alarm circuit circuit.
For sensing the door position different types of methods can be used such as magnetic light beam mechanical electrical etc.
Working of security alarm circuit.