design idea? How to use one signal to drive 2 LEDs?

[luben111]

How to drive 2 LEDs from one wire

Hi,

An old idea, that I realized many years ago.

You make one voltage of let's say 2.5V - by simple 2 resistors.

You connect two LEDs to the uP pin and other end to the middl epoint of resistors.

LEDs are with oposide ends - when you push the uP pin to 0 - one of LEDs is lighting, other is dark and visa versa.

When you make the pin TRISTATE - no lighting..

Regards
Luben

 

[atmel2000]

Re: How to drive 2 LEDs from one wire

Hi Luben,

Your idea is good but there are 2 disadvantages:

1. there is a high power consumption even if the leds are not working
because the resistors must be around 470 Om each - that means
5mA or more all the time.

2. You cannot turn on 2 leds at the same time. You can do this only
with 50% modulation but then you have to decrease the value of the
resistors and the power consumption is going up.

Anyway, the idea is very good - I like it!

Atmel2000