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.
We will use a knife switch in conjunction with a 10kω resistor the 2 of these components form a voltage divider circuit.
Schematic of the door opening alert circuit.
A door opening alarm circuit is an indicator or a security alert device which activates while opening the device attached door.
The door opening alarm circuit or front office visitor alert is used for alerting you when a customer is at your office shop.
As a result pin 4 of ne555 also goes low and the timer does.
When the door is closed the magnet is close to the sensor.
Pull pin security alarm circuit.
Door open alarm circuit.
It will produce a beep sound when each new customer or visitor is entering and will automatically switch off after few seconds.
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.
Working of security alarm circuit.
Door alarm circuit circuit.
Presence of north polarity magnetic field generates a low voltage at the output of the sensor.
The schematic for the door alarm circuit is shown below.
For sensing the door position different types of methods can be used such as magnetic light beam mechanical electrical etc.