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Simple question

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techguy101010

New Member
Hi,
I'm trying to set up a circuit in which 2 buttons trigger the following:
Button 1: Lights LEDs A and B
Button 2: Lights LEDs A and C
I'm running into a problem here because when I press Button 1, LEDs A, B and C all light up. The reasonable explanation for this behavior is that by connecting A to B and A to C, I've effectively connected A to C.
How do I get around this? I know this is a very fundamental thing.
Thanks
 

microtexan

New Member
How about showing us your circuit. Also think about lighting LED B and A with button one and then LED C and LED A with button two. (Think extra diode);)
 

techguy101010

New Member
Thanks for your help.
I'm sorry, I don't understand what you mean in saying think extra diode.
The circuit is like this:

+5V _______________/ B1 ______A, B____ GROUND
+5V _______________/ B2 ______A, C____ GROUND

(Read "A, B" as branch off to both A and B, both of which then go to ground)
Thanks
 

KMoffett

Well-Known Member
This is done with "diode OR'ing".

Ken
 

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  • Diode OR'ing.gif
    Diode OR'ing.gif
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crutschow

Well-Known Member
Most Helpful Member

KMoffett

Well-Known Member
OK. Two options. (Buttons were not spec'ed as SPST-NO)

Ken
 

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  • 2Button3LED2.gif
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KMoffett

Well-Known Member
One more simplification. ;)

Ken
 

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  • 2Button3LED3.gif
    2Button3LED3.gif
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Roff

Well-Known Member
One more simplification. ;)

Ken
Excellent, Ken. An added advantage is that the current in DA remains almost constant if you have both switches closed, instead of nearly doubling as it would in the previous version, which was almost excellent.:D
 
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