To help how to make Dark LED using LDR and 555 timer in an easy way..

1. DARK DETECTING
LED USING LDR AND
555 TIMER IC

2. COMPONENT
1. 555 Timer IC
2. LED
3. LDR
4. RESISTOR(1k,47k,4.7k ohms)
5. Capacitors(0.01uf,1uf)
6. Battery 9V
7. Matrix Board
8. Connecting Wires

3. 1. 555 TIMER IC

4. 2. LED

5. 3. LDR

6. 4. RESISTOR

7. 5. CAPACITOR

8. 6. BATTERY

9. 7. MATRIX BOARD

10. 8. CONNECTING WIRES

11. CIRCUIT DIAGRAM

12. DISCUSSION
1. The circuit diagram of dark detecting LED. This
circuit shows how we can convert a simple a
stable mode circuit to a “dark sensor”. We just
need to add an LDR and a resistor in the circuit,
then it simply works as dark detector.
2. A general proper light is falling on the LDR its
resistance is very low.

13. 4. When there is no light the LDR resistance
increases.
5. At this time the IC is triggered and glows the LED
attached with the circuit.

14. CONCLUSION
• 555 Timer is a highly stable device for generating
accurate time delays or oscillation. Additional
terminals are provided for triggering or resetting if
desired.