ok, this should be a relatively simple circuit to make.

basically, the story behind this is that myself and a few mates have a competition every halloween (we all throw €20 in) to see who can come up with the most random costume. last year, the guy who won went as a washing machine. the year before that, another guy won for being the black sillhouette from the ipod adds. each year, the winner gets about €120, so it pays for the night out really. This year, i'm going as a set of traffic lights. I have everything for it EXCEPT, the lighting circuits.

The way i've decided to do it is with 3 seperate lighting circuits. one for red lights, one for amber, and one for green. The diameter of each circle to be illuminated is the same as a cd. so for each circuit, i'd need about 5 led's i guess, and all on a simple on-off timer, with about a 10-15 second delay between on off. i reckon i'll power each circuit with a 9v battery.

i couldn't design a circuit if my life depended on it. could someone help me out?

 

A quick google gives this:
http://www.kpsec.freeuk.com/projects/trafficlight.htm

you will need to adapt it slightly to cater for the number of LEDs you want to power though.

HTH
Cheers
Shaun

 

Hello,

I found also a schematic with hints how to connect leds or lamps.
http://home.cogeco.ca/~rpaisley4/20step.html

Greetings,
Bertus

 

that first one looks a little easier. If i just made the resistor before each led a bit less, i could put 5 leds in each, right (ie, 5 red, 5 amber, 5 green) and what kind of battery life would i get with 15 leds?

 

that first one looks a little easier. If i just made the resistor before each led a bit less, i could put 5 leds in each, right (ie, 5 red, 5 amber, 5 green) and what kind of battery life would i get with 15 leds?

Remember that the 4017 can only source a certain amount of current... I can't remember how much but I'm sure someone here will be able to tell you or failing that have a look for a datasheet.

either way, I'm not certain it would be able to supply enough current for all those LED's... you may need to add transistors on the outputs.

as for battery life... again I'm sure someone would do the calculations for you... but I would say a 9v battery (PP3) would deffinately be fine for a nights entertainment

Cheers
Shaun

 

The 4017 can source or sink only a tiny amount of current. Driver transistors are most definitely in order.

Regarding discharge curves on 9V batteries, have a look here: http://www.powerstream.com/9V-Alkaline-tests.htm As can be plainly seen, a lone 9V battery will simply not be up to the task. I suggest a pack alkaline or lithium metal cells instead: http://www.powerstream.com/9V-Alkaline-tests.htm

 

hmmm.... i see... well, to be honest with you, the simpler the circuit, the better, so i think if i could just go with red and green oscillating back and forth every 10 seconds or so. I've a vague recollection of doing that with a 555 timer. but i don't know how i'd go about putting 5 led's in there. anyone got a simple 555 oscilator circuit for led's lying around?

 

I was thinking about this, with 3 555's you can have a yellow, and timing too.