Traffic light Circuit

Thread Starter

daskywalker

Joined Mar 28, 2010
13
Here I am again, with the traffic light project I am constructing below:

http://www.bowdenshobbycircuits.info/traffic.gif

So now I have to write a detailed report on the role of each component in the diagram. I know the 555 timer provides the one-shot pulse and you can adjust the pulse duration with the capacitor and resistors. I am not sure why the transistors before the LEDs are there.
I also know that the diodes act as some kind of logic gate. Anyone know how it affects the counting sequence of the LEDs?
I guess the counting sequence of the 4017 counter is on their datasheet right?

Next part. I was thinking about adding a switch so that when switched on both sets of lights will flash yellow ONLY. Do I need to add a separate counter for that or can I put the switch between the 555 timer and the decade counter, so that the 555 timer pulse goes straight to the yellow LEDs?

Many thanks.
 
Last edited:
Top