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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

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)

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

This is done with "diode OR'ing".

Ken

#### Attachments

• Diode OR'ing.gif
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Now for the real challenge -- Do it without diodes

Now for the real challenge -- Do it without diodes
With single pole switches and no other electronics?

Thanks, I got it working with diodes.
How would you do it with single pole switches

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

Ken

#### Attachments

• 2Button3LED.gif
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• 2Button3LED2.gif
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One more simplification.

Ken

#### Attachments

• 2Button3LED3.gif
3.5 KB · Views: 140
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.

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