Hey guys, I'm stuck on this problem and was wondering if anyone could lend a hand or point me in the right direction. I need to design a traffic light circuit using one 555 timer and three LEDs so the lights flash in the sequence of green, yellow, red. Each light needs to stay on for 1 second, and then the cycle has to repeat itself. I have an idea of how to do this with three 555 timers, but have no idea how to do it with just one. Thanks in advance!

 

Get a decade counter. And connect the 4th output to the reset.

The first 3 outputs will be for the red, green, blue.

That's my guess.

 

Check out this page:

http://www.doctronics.co.uk/4017.htm

 

ahhh, thanks a bunch. that would work out great, but if can't get my hands on a counter do you suppose there would be another way to go about it?

 

You could use a Pic for sure...but I don't see how you could get a pic and not one of those things. There are sooo many internet companies selling these chips, or similar counters.

 

Howdy,

The URL that TrevorP gave above looks good, and the parts are easily obtainable. Also, someone else on this board was just recently doing the same thing. Search for "traffic light."

FYI,
Corey

 

If you can't get a 555, just use an astable multivibrator...it's only a couple of transistors, resistors and capacitors.

 

Hello...
I have virtually very limited knowledge in electronics although I can read schematics. Can anybody help me or point me to a source where I can find a schematic to build a down counter that counts from anynumber (2 digit) down to zero.

Any help would be greatly appreciated. Thanks.

John

 

Your request is not related to this thread's topic. Please don't hijack threads.

 

Well the simplest and cheapest solution would be the Picaxe 08M chip.

http://www.sparkfun.com/commerce/pro...oducts_id=8308

Software to program the chip from a windows PC is free for downloading and uses a simple Basic language. No hardware programmer is required, just a comm cable and two resistors. This Pic chip can drive the Leds directly, so it's truly a one chip solution, plus LEDs and a battery or power supply of course.

Lefty

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