Need Help with Simple Circuit

Discussion in 'General Electronics Chat' started by beeson76, Apr 20, 2010.

  1. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    I have a simple circuit that I need help with. I want to power 2 LEDS from a power source--a red and green LED. When I "switch" the circuit on I would like the red LED to light--very simple. But when a tilt switch is activated at about 30 degrees, I would like the red switch to go off and the green LED to light, showing that it is over 30 degrees. Any suggestions. For this project, the simpler the better. Thanks in advance for any help and suggestions.
     
  2. Mike33

    AAC Fanatic!

    Feb 4, 2005
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  3. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    Mike33.

    Thanks for the reply with links. After looking at them, I had an idea like what they call the "common emitter mode"--where current will take the path with less resistance. But I would like for the Red LED to shut off completely (no current at all going to it). And it looks like with this circuit, the Green LED is on all the time too, unless I put the tilt switches between the "start" of the high current circuit and the diode--just thought of that. So that would work, but still the Red LED is still on. Any thoughts??? You mentioned using 2 transistors--could you please tell me what you had in mind? Thanks.
     
  4. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    Try this. You just need an extra LED.

    [​IMG]
     
  5. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    Thanks Eblc1388.

    It seems to be working. Is there any way of doing this by replacing the extra LED with a resistor? Also I would still like to know how I could do this with a transistor too. So any help in that area would be great. Thanks.
     
  6. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    The more I am messing around with this circuit Eblc1388, the more interesting it is. So is this a simple "showing" of how current takes the path of least resistance??? This is awesome!
     
  7. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
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    No. You can't replace the extra LED with a resistor.

    The important thing here is whether the circuit actually solves your problem?
     
  8. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    I am going to have the Red LED and the Green LED stick out of a small hobby box. So I would just have to keep the extra LED inside the box if I were to do it this way. Could I replace the extra LED with another sort of diode??? Thanks for the replies Eblc1388.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You might replace the 2nd LED with a Zener diode; one rated about 2.2v to 3.3v.

    Or just put some shrink tubing around the 2nd LED.
     
  10. beeson76

    Thread Starter Member

    Apr 19, 2010
    185
    1
    Thanks SgtWookie.

    I tried your suggestion and it works great!!! It appears the LED is "shutting off" completely. Thanks again. I will use this design. Thanks for all the input. And just so I know in the future, any suggestions on getting this to work with a transistor would be greatly appreciated too. But the design that you guys suggested is probably the simplest design someone can come up with, so I really appreciate the suggestions.
     
  11. Wendy

    Moderator

    Mar 24, 2008
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