7 Fading LED

This a dual fading led using 555 timer IC. When first LED (Red) starts to increase its light intensity, the other LED (Blue) starts  to get dim. See the fading sequence diagram of the two LEDs below to understand how it works.
fading sequence diagram 
schematic diagram
Part list:
1-555 IC
2-150 ohms resistor
1-20k ohms resistor
1-Red LED
1-Green LED (note :Blue in diagram)
1-220uF/16V electrolytic capacitor
1-NPN transistor (2N2222, 9013, other general purpose NPN)
1-PNP transistor (9012, other general purpose PNP)
1-9V battery


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7 comments:

  1. Acme FixerOctober 20, 2011 at 5:53 AM

    I didn't see a ground pin on the 555 chip. Label, also.

    ReplyDelete
  2. DH-gmOctober 20, 2011 at 5:56 AM

    Yeah you are right, ground is in pin 1 ill redraw it. Thanks a lot for the info.

    ReplyDelete
  3. AnonymousJuly 20, 2012 at 5:47 AM

    How can you vary the speed of the fading?

    Thanks

    ReplyDelete
    Replies
    1. UnknownJune 6, 2016 at 3:38 PM

      change the clocking speed change the capacitor!

      Delete
    2. UnknownJune 6, 2016 at 3:39 PM

      change the clocking speed change the capacitor!

      Delete
  4. cuyler1February 13, 2016 at 2:41 AM

    would you take the old one off the internet. my grand daughter copied this and burnt 3 led's out. if all the inadequate circuits where removed from the net children could learn instead of being discouraged.

    ReplyDelete
  5. cuyler1February 13, 2016 at 2:41 AM

    would you take the old one off the internet. my grand daughter copied this and burnt 3 led's out. if all the inadequate circuits where removed from the net children could learn instead of being discouraged.

    ReplyDelete

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