Monday 24 August 2015

breadboard - Only one LED is working on this traffic light circuit


I have a problem with my traffic light circuit. I've made sure of the wiring and everything seems right but for some reason only the yellow LED is lit constantly without it flashing and the other 2 LEDs are not even working. It's my first circuit so I feel a bit lost.


Here are some pictures of my circuit:



I didn't use the 0.1uf


enter image description here


Here's the circuit diagram that I'm using: BTW I didn't use the 0.1uf since I didn't have any enter image description here


I've got it from this website here




Edit


After receiving your answers, I have corrected the breadboard errors. Now only the red LED is lit. Here are two new pictures:


pic1


pic2



Answer




It looks like you are misunderstanding the way a breadboard is wired internally. Check out this link for information.


Here is an image, taken from that link:


breadboard


One issue you have, as an example, is the resistor connected to your green LED. Both leads are plugged into a single node, and therefore it doesn't act to bring power to your LED (or do anything at all).


To see what I mean, look at this next image. All the holes marked by the green line are connected, and the blue holes are also connected. However, there is no connection through the red line. The green and blue lines aren't connected to each other.


example




Edit:


Regarding your modified circuit, the breadboard corrections look good. Here's what else I see:





  1. You'll need to connect all the power busses together (and the ground busses). Often, this simply requires putting a wire from the V+ rail on one side to the V+ rail on the other side, and again for the ground busses. However, as RJR points out (see his comment below) it appears that your breadboard has multiple power busses along each edge ("V3", "V4", etc). If these are, in fact, not connected to each other, then you'll have to do it with wires.




  2. The diode from pin1 of the 4017 appears backwards.




  3. You'll want to check the polarity of your LEDs. I can't tell from the pictures if they are oriented correctly.





Good luck!


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