I am the IEEE Project Coordinator at my university and I am trying to teach beginners to electronics the concept of bread-boarding and how to use the 555 timer.
Now I consider myself a pretty knowledgable person in electronics and this is why I'm kind of annoyed.
I was going to show them this circuit , BI-POLAR LED DRIVER Circuit but for some reason it just isn't running. I have it wired up like the image but it just won't run!
Have you tried swapping parts out or even swapping out the breadboard? I know from my school days that students often put bad parts back in the parts drawers. It shouldn't take long to completely start over with new parts.
What?! Really? Maybe I'm not as good a breadboarder as I thought I was.
I should point out that I don't have a bi-color led like the thing says, so I'm just using two leds set up like the diagram.
Interesting....
When I connect up the 2nd led in the backwards direction with the resistor going to GND. the whole circuit turns off. I thought that those two resistors might just be shorting out the whole circuit.
This is a little different situation isn't it? The LEDs might be in parallel, but they are never on at the same time since they are reversed, so this wouldn't apply, right?
So with a 5v supply maybe 12 at a push what is the best way to power 256 ir led's? all with the same signal a pwm signal. After much head scratching and taking apart a 60 led torch to find all led in parallel and one resistor, i decided on a constant currant led driver and to put them in groups of around 700ma(what the driver is rated at). Now the led are rated at 20ma maybe more for pulsing, i have them running at around 10ma. My thought was an i think i'm wrong now was that at that currant there would be no heating and no thermal runaway.
funkyguy4000:
Interesting....
When I connect up the 2nd led in the backwards direction with the resistor going to GND. the whole circuit turns off. I thought that those two resistors might just be shorting out the whole circuit.
Is that whats going on?
If you moved the top 220R resistor to go to Gnd, then there is no power reaching pins 2 and 6.