traffic lights??

Discussion in 'The Projects Forum' started by trad3mark, Sep 4, 2008.

May 11, 2008
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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?

2. ShaunManners Active Member

Feb 16, 2008
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Apr 5, 2008
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May 11, 2008
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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?

5. ShaunManners Active Member

Feb 16, 2008
72
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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

6. thingmaker3 Retired Moderator

May 16, 2005
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May 11, 2008
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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?

Mar 24, 2008
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