LED Fading/Blinking using 555 IC

This circuit makes a LED fade on and off.  first charges a 100u and the transistor amplifies the current entering the 100u and delivers 100 times this value to the LED via the collector-emitter pins. The circuit needs 9v for operation since pin 2 of the 555 detects 2/3Vcc before changing the state of the output so we only have a maximum of 5.5v via a 470R/220R resistor to illuminate the LED.

 

COMPONENTS REQUIRED:

1. one 470ohm / 220ohm  resistor 

2. one 33k resistor

3. one LED ( I used Blue)
4. one 100uf Capacitor
5. one 555 Timer

6. one Generic NPN Transistor (2222A)

7. one 9-12V Supply

STEPS :

1. Place 555 Timer
2. Connect Pin 1 To Ground
3. Connect Pin 2  to Base of NPN
4. Connect 33K resistor between Pin 3 and base of NPN
5. Connect Pin 4 to Pin 8
6. Connect Pin 6  to Pin 2
7. Connect Pin 8  to Positive voltage

8. Connect Emitter of NPN to 470ohm resistor to longer leg of LED,Connect shorter leg to ground
9. Connect Base of NPN to + side of cap, then ground - side
10. Connect Collector of NPN to + voltage

Resistance b/w pin3 of 555 and base of NPN(2222A)

30K/33K - Fadein,Fade out
220ohm - Fast blink
1K - Blink
470ohm - Slow blink
100K - Faded start

(NOTE :  Below i used a combination of resistors equal to 30K  to Fade in and Fade out a LED )