Simple Dark Sensor Circuit for Security using IC 555 timer

Simple Dark Sensor Circuit for Security using IC 555 timer is useful project for security, it senses low light and turns ON the buzzer or light.

Also, the circuit uses an LDR for light sensing and works well in night lights and alert systems.

Furthermore, it includes a 555 IC, an LDR, resistors, a capacitor and a buzzer and it also operates from a 9V battery.

Circuit Working:

Parts List:

Components	Values	Quantity
Resistors (All resistors are 1/4 watt)	100k, 1M	1 each
	Potentiometer 1k	1
	LDR	1
Capacitor	Ceramic 1000pF	1
Semiconductors	IC 555	1
	Buzzer	1
	Battery 9V	1

To begin with, this circuit for dark detector works on LDR change resistance with light.

In bright light the LDR is with low resistance and with more current flow and keeps IC1 from working and in dark the LDR is with high resistance and voltage at pin 2 changes.

Therefore, this make 555 timer turn ON in monostable mode and buzzer beeps as warning.

How to Build:

To build a Simple Dark Sensor Circuit for Security using IC 555 timer follow the below mentioned steps:

• First, assemble all parts as per circuit diagram.
• Next, connect pin 1 of IC1 to GND of circuit.
• Then connect pin 2 of IC1 to pin 6 of IC1 and now connect resistor R2 between pin 2 and pin 6 and pin 3 of IC1.
• After that, connect pin 3 of IC1 to one terminal of VR1 pot and connect other terminal of VR1 to one end of buzzer and connect other end of buzzer to GND.
• Also, connect pin 4 and pin 8 of IC1 to +9V battery positive and then connect resistor R1 between pin 4 and pin 8 of IC1.
• Further, connect capacitor C1 from pin 2 to GND and finally, connect LDR R3 between pin 4 and GND.

Conclusion:

Overall, Simple Dark Sensor Circuit for Security using IC 555 timer detect dark and turns ON an alert, also it changes resistor for sensitivity.

Furthermore, the circuit is good for home automation, security and energy saving.