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homemade stoplight

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Tallon Karde

New Member
I have an old traffic light that I want to power with LEDs and an AC/DC 9-12volt plug-in converter. I know how to do that easy enough, but I want a device that will (when powered on) light the green lite for 8sec, switch to yellow lite for 8sec, switch to red lite for 8sec, then start over at the green lite. I want it to continue to loop until the unit is powered off. I would like to either purchase or build this, or a combination, which ever will be cheaper. I think it can be done with a 555 timer but I'm not sure how. Any ideas? thanks.
 

ke5frf

New Member
You can use a 555 timer and a 4017 decade counter by feeding the 4th output to the reset pin. This will give you three drivers sequentially switched.

Don't know about your lamps. Tell us more about them, an old traffic light? A real one? This is AC or DC powered? You were a little vague. You'll probably need relays on the outputs of the decade counter.
 
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Mike_2545

Super Moderator
Well what-ever you do, dont do this :)
 

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Tallon Karde

New Member
Thanks for the reply. The stoplight is actually the real thing. it has ac bulbs and is wired to ac right now but I intend to remove the bulbs and make LED lights to put in place of the old style bulbs as this is an old light. I intend to convert it to a dc system with a "radio shack" ac/dc converter that plugs in to the wall. I wouldn't think that I would need relays but nothing is out of the question at this point...definitely dont want to recreate the picture. thanks
 

ke5frf

New Member
Thanks for the reply. The stoplight is actually the real thing. it has ac bulbs and is wired to ac right now but I intend to remove the bulbs and make LED lights to put in place of the old style bulbs as this is an old light. I intend to convert it to a dc system with a "radio shack" ac/dc converter that plugs in to the wall. I wouldn't think that I would need relays but nothing is out of the question at this point...definitely dont want to recreate the picture. thanks

Well then, build the circuit I described in the first post, directly driving the LEDs from the decade counter which will be triggered by the 555 timer.

As I said, the 4th output of the decade counter will need to feed back to the counter reset to resequence your LEDs.

This should be a simple circuit to implement, and plenty of circuit designs can be found by Googling "decade counter" and "555 timer."
 

Artificer

New Member
The counter (above) is your best bet, by far. Might I suggest 12 volts for supply, as most LED refit trailer light kits already have a light plate of approximately the correct size. Load is on the order of 180mA, requiring only a small driver transistor.
Try Projects of interest for photos of such a light fixture being modified.
Were you to wire two in series (corresponding opposites) the output would be viable, but not blinding, at 6 volts each.
 

Tallon Karde

New Member
solutions

got what I need to complete the circuit. thanks for the information. I will be using a 555 timer and the 4017 with mosfet drivers for my lights so that I can use enough LEDs to get the illumins I need. Should be simple enough if I get the load currents right so that I don't fry anything.
 
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