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Can I get help making a simple circuit for two LEDs? Answered

I can't find a circuit online or get any of my experimental circuits to work. I have been trying circuits with transistors - specifically the 2n3904.

All I want to do is make a circuit that has two LEDs and any kind of switch. I want one LED to always be on. Then, once the button is pressed, the first one goes off and the second one comes on. I do not want to use an arduino or anything like that. I don't really care what components are needed I just want it to work.

Any help or guidance is appreciated. Thanks

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iceng
iceng

4 years ago

What are the colors of the leds

red-green.jpg
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iceng
iceng

Answer 4 years ago

The way it works, is the RED LED uses less voltage then the GREEN LED.

The red led lowers the voltage below what the green led needs to light up... A fun demo of forward diode voltage that you need to take into account when making a design...

This will not work with two white or identical LEDs...

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Nighter3D
Nighter3D

4 years ago

Hmmm. so you want a Toggle switch?

If wanting for a discrete solution that can using a simple button then you will want to make a Set/Reset Flip-flop (sometimes called a SR Latch). you can make those through transistors and very simple chips like the ever venerable 555.

Personally the 555 would be the best solution as it starts reliable in "off" on power-up till you press the set button. Simple Transistor flip-flops need to be triggered first. look for "555 Bistable" and you should see it's very simple

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Downunder35m
Downunder35m

4 years ago

Astable flip flop, plenty of schematics available in all sorts of variations.
If you search Google for LED circuits you sooner or later come across one website with over 50 examples - all well documented and explained.