# Alternating 3 LED project

I am making a Halloween costume for my son and it needs some light. Basically he's a character from the Mario Bros universe that carries a traffic light on a fishing pole (Lakitu in Mario Kart). I am trying to figure out a way to light the traffic lights red, green, and yellow lights using leds in a single circuit that would turn them on and off independently. Just something simple that goes red, then yellow, then green, then back to red over and over. Is there something to build or a circuit diagram? I really have never done any wiring like this ever, so the easier the better. Thanks for your help.

• A micro controller? Two 555? Oct 8, 2018 at 20:03
• What country are you in? "... goes red, then yellow, then green ..." Shouldn't that be the green, yellow, red? Oct 8, 2018 at 20:03
• @transistor it's a race light. They go red to green. Oct 8, 2018 at 20:35
• @Passerby: Ah-ha! That explains it. "Traffic light" probably isn't the right term then. I never had a Mario game. We had wooden blocks, Lego, bikes and Matchbox cars and, maybe, Scalextric or a train set. Oct 8, 2018 at 20:40
• I added a gif. The light has changed over a few games, so the specific colors and sequence probably doesn't matter. The general idea is the same. Oct 8, 2018 at 20:54

This is very simple LED chaser circuit

Use a 74HC4017 for more drive current.

What you do is use multiple LEDs for each color.
Only one will be on at any given time.

LED1-4 Red
LED5-6 Yellow
LED7-10 Green

You could do something more like this:

Yellow 1 LED 1-2
Yellow 2 LED 3-4
Yellow 3 LED 5-6
Green LED 7-10

If you want high driver current add a buffer driver or inverting buffer

Here's one that's a bit of trouble to make.

Figure 1. Source: MarvinSafe.

Instead, I recommend that you make a manually switched circuit with a 4-way slide switch. This could easily be mounted in the pole of the lights.

Figure 2. A 4-way slide switch. This one is dual-pole: the near set of contacts and far set of contacts are duplicates. We only need on set for this project.

simulate this circuit – Schematic created using CircuitLab

Figure 2. A thumb-operated 4-way slide-switch wiring.

The current requirement depends on your LEDs. When you buy them figure out what their rated current is and you can calculate the appropriate value for R1 using many of the online calculators. For some theory see my article Ohm's law and resistor calculation.

If you need more LEDs for brightness then connect them in parallel. Usually this is a bad idea but for this simple temporary application it would be fine.

• Why would the CD4017 be difficult? The manual switch is the opposite of what op wants anyway. Oct 8, 2018 at 20:47
• "I really have never done any wiring like this ever, so the easier the better." 19 components, breadboard / stripboard, IC sockets, soldering, anti-static precautions, etc. It's not complicated if you have the equipment, time and access to parts but it all has to be packaged too. My Figure 2 is very low-tech and may do the job and puts the child in control! Oct 8, 2018 at 21:06
• The 4017 IC lights only one LED color at a time unless you add a bunch of diodes to make AND gating. Oct 9, 2018 at 0:45
• @Audio: My Figure 1 shows a bunch of diodes to make AND gating. Oct 9, 2018 at 6:46