Hi guys,
I am doing a project with LEDs on traffic light
I have connected the RED and GREEN leds in reverse polarity and took the input to these pins to an AND gate and connected the output to YELLOW led.
when i am running the pgm i use the following logic
01 for RED
10 for GREEN
11 for YELLOW
but in my circuit my yellow light is ON with a minimum brightness even when the other LEDs are ON
what is the problem?????
ok, i am no expert when it comes to this stuff, so take what i say with a grain of salt. but if i had to guess, the ground from one of your LEDs is activating your AND gate. take a look at the diagram i attached. that is my guess what is happening. but again, i could be completely wrong. im just letting you know what my guess is when it comes to this problem.
My take is slightly different from that of suicidalacorn's... I think that with either 01 or 10 and therefore activating the R xor G LEDs, there's enough of a "short" across the AND gate for it to read both its inputs as 1's.
(Which is what suicidalacorn was saying, on second thoughts, now that I see his annotated pic....)
So now do a proper one, showing each LED and the series resistor connected to each LED along with values.
In other words a schematic that people can understand.
What are you trying to achieve? You mentioned a traffic light. Do you mean that you only want one of the LED's on at a time or do you want the Yellow to light up when the Red AND Green are on?
You may want to use inverters as well if you want only one on at a time.
I remmember once trying to dirrectly drive a seven segment display with my Arduino and the segments were really dim I checked and found that I forgot to put