# Switching between two LEDs

Discussion in 'The Projects Forum' started by Netguru5, Oct 31, 2009.

1. ### Netguru5 Thread Starter New Member

Oct 28, 2009
4
0
Hopefully, this should be simple for you gurus! I need help designing a curcuit on a breadboard that switches between two different colored LED's operated with a momentary switch. I also need a 1 second delay between the transition. I would appreciate any help.

Thanks

2. ### ELECTRONERD Senior Member

May 26, 2009
1,146
16
Why don't you try something like this:

Using the following equation, $T = RC$ Where T = Time, R = Resistor Value, and C = Capacitor value, you can set the time.

Austin

3. ### Wendy Moderator

Mar 24, 2008
20,874
2,654
Do you want to toggle between them, or light one momentarily and go back to the original. If it is the latter soemthing like this?

555 Monostable

4. ### Netguru5 Thread Starter New Member

Oct 28, 2009
4
0
Sorry, I should have been more clear, I want to be able to toggle between the two LEDs when the momentary switch is engaged. Here is a flow of the desired function.

* Power supply comes on and LED1 is Lit.
* Momentary switched is engaged
* LED1 goes OFF
* 1 second delay
* LED2 is lit
* Momentary switched is engaged
* LED2 goes OFF
* 1 second delay
* LED1 is lit

I woud also like to retain which LED was last lit when the PS is turned off, then back on.

5. ### Wendy Moderator

Mar 24, 2008
20,874
2,654
That last one is a kicker, for a electronic circuit to remember its state it needs power. You either have to have a form of standby power or a mechanical setup, IMO.

6. ### ELECTRONERD Senior Member

May 26, 2009
1,146
16
Hi Netguru5,

I believe I buit that same circuit from the "500-In-One Project Lab," but I'm not sure. If you can't find a free manual for it online, I'd be glad to take a look for you in mine.

Austin

7. ### KMoffett AAC Fanatic!

Dec 19, 2007
2,619
243
Three resistors, two LEDs, a pushbutton switch, and an 8-pin PIC. Otherwise a small bistable latching relay would be my simple memory of choice. Don't have a circuit at the moment though.

Ken