this is a basic traffic light timer that can be used for a model city or just as a little project to show off.

to change the delay on the traffic light you can use the trimpot. if you what to have an even longer delay you can use a 100uf capacitor.

it is important to note that the led connecters are very close together and that will make it harder to solder.

i made this project to practice pcb design and populating a pcb.

the way it works is that the trimpot changes the rate the capacitor charges which will ether speed up or slow down the rate at which the lights change. the 555 chip will advance the 4017 decade counter chip by one with the outputs of it going to the leds. the green led is connected to 4 of the outputs so it will be lit longer and is protected with diodes.

the list of components are in a zip folder

for any one interested i used a schematic that i found online