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Need help with LEDs

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Homer

New Member
Ok, I want to design a circuit for a pet project where I control two LEDs. Basically, the two LEDs are at the same brightness. When I press a switch, one LED glows brighter than the other, but the other LED is not allowed to glow dimmer. How can I design this? What do I need? So far my parallel circuit isn't work for obvious reasons. Thanks.
 

crust

Member
How about biasing your diode to say 1.8V or so by putting your LED in series with a resistor. Then put a series combination of a pushbutton and another resistor in parallel with your first resistor. Now when you press the button you have lowered the value of the current limiting resistor and your LED will glow brighter.
 

Homer

New Member
crust said:
How about biasing your diode to say 1.8V or so by putting your LED in series with a resistor. Then put a series combination of a pushbutton and another resistor in parallel with your first resistor. Now when you press the button you have lowered the value of the current limiting resistor and your LED will glow brighter.
Yes that covers the glowing part, but the other LED will glow dimmer as a result...
 

EMF1

New Member
LED Dimmer

Hello,

I would suggest a simple voltage regulator circuit in series with one LED but paralled with another LED that is has a current limiting series resistor using a SPDT switch to go back and forth. This will allow a constant both on at same brightness or one brighter than the other with out dimming during switching. I would suggest a using an NpN small signal biased just below saturation.
 
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