Want to change LED to dual color for...

[wilykat]

One of my game system has a single LED, it only lights up when the CD is accessed. I wanted to add power LED to my Turbo DUO system so I can see if I left it on or something and it's not playing CD game. It would suck if I plugged or unplugged a game controller or something while the system is on.

After looking into the existing circuit, it's like this

The base of the transistor goes to CD drive circuit, I am not sure what voltage it is so it'd probably be easier to tap into emitter side since I'd get +5v before resistor.

I have a bunch of 2 lead bi-color LED. How could I wire them in a way that it'd power on one color (say, green) and when the CD is accessed, it'd show another color (red). Or would it be easier to use a 3 lead version? Common anode or cathode? I'd prefer not to have yellow (red+green) so one LED would need to go off when CD light goes on.

TIA!!!

 

[dougy83]

A 3 pin LED common-cathode is easier: just connect one of its LEDs in-place of the LED you've shown in your diagram, and the anode of the other LED is connected to VCC through a resistor. If you don't want yellow, use a red/blue LED.

To drive a two pin LED, you can use a couple of inverters, with the input marked "INPUT" on the diagram below connected to the CD-active signal from your console.

(ref https://electronics.stackexchange.com/questions/30174/antiparallel-led-driving-circuit)

 

[wilykat]

Thanks!!

 

[wilykat]

I ended up leaving the original LED alone and hot-gluing new LED next to it using a transistor to act like a NOT gate. More on this at game forum: **broken link removed**

And yes it works, the blue power LED goes off when red LED comes on.