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led help????

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bazbalz

New Member
how do i a switch and a blue and red led, so tht when the switch is turned on the blue led comes on and the red led is off and when the switch is turn off the red led come on and the blue goes off???

probs simple but not a clue
help me
 

k7elp60

Active Member
We need some more information in order to help you.
What is the source of power that you are switching and what kind of switch is it?
 

bazbalz

New Member
the power source is a car battery and the switch is a normal toggle switch you get with a cold cathode set.
 

MikeMl

Well-Known Member
Most Helpful Member
Does the switch have three terminals or only two?
 

MikeMl

Well-Known Member
Most Helpful Member
it only has two to i need a 3 way? or is it possible to do it with a 2 way?
Only by adding external components like a transistor or relay.

One other possibility: what are the part numbers of the two LEDs you are planning to use?
 
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bazbalz

New Member
no idea lol not much help am i lol. i got a red and blue led and a blue neon and a 2 way rocker switch and i know how to wire it up so when the neon is on the blue led lights up just dont know how to wire it up so tht when the neon is off the red led lights up and the blue led dont
 

MikeMl

Well-Known Member
Most Helpful Member
Try this. This relies on the fact that Red and Blue LEDs do not have the same forward voltage. Since I can't remember which has the higher forward drop, you will have to try it both ways.
 

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bazbalz

New Member
the single pole had only 2 connects just like the rocker switch i already have just the switch bit looks different
 

MikeMl

Well-Known Member
Most Helpful Member
Did you move the switch so that it is in-series with the other LED?
 
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BrownOut

Banned
the single pole had only 2 connects just like the rocker switch i already have just the switch bit looks different
I said "single pole, double throw" It has 3 connections, 1 input and two output. Use 1 output for the blue led and the other output for the red one.
 

sheldonstv

New Member
Throw that switch away and buy a spdt(single pole double throw)switch and wire it as my schematic shows....its no good me giving you a schematic for using that switch you have because there is no need to make things complicated.... get a single pole double throw switch, two 470 ohm resistors ,your two leds and the schematic is uploaded for you .....do try not to be too scared.......
 

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Hero999

Banned
BrownOut,
That won't work, when the switch is off both LEDs will light.

Mike,
You got it backwards, reds have a lower voltage drop than blues.

The solution is to make it so the red has a higher voltage drop, whether it be by using a potential divider of a zener. The zener option is better.

Another option is to use a transistor and a pull-up resistor with the switch pulling it down to turn it off.
 

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BrownOut

Banned
Thanks for the correction, Hero, but you mis-spelled BrownOut HEH!
 
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Hero999

Banned
I've corrected my spelling.
 

sheldonstv

New Member
how do i a switch and a blue and red led, so tht when the switch is turned on the blue led comes on and the red led is off and when the switch is turn off the red led come on and the blue goes off???

probs simple but not a clue
help me
heres the schematic again with the switch shown operated in both possible positions with the respectve leds shown that will be on(or off).....do not be scared of it.....thats one way to use his existing switch i suppose but look at all the extra parts invoved ...im sure as long as bazbalz sees the leds light up when he operates his brand new spdt(single pole double throw)switch thats all that matters -let ther be lightssssssssssssssssssssssssssss
dont be scared of the spdt switch!!!!
 

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