Instructables

RGB LED Color Sequencer - without a Microprocessor

Picture of RGB LED Color Sequencer - without a Microprocessor
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Display the color combinations of color LEDs without using a microprocessor.

Using a single logic chip which costs under 50-cents, you can make a simple color cycle display for RGB LEDs. The multiple taps along the top are used to 'program' the display for sequence and brightness.
 
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Step 1: The parts

You will need:

RGB LED - I used one purchased here. This is a common anode version, so if you have a different configuration, you must adjust the connections.
1 x 74HC04 Hex Inverter IC chip (p/n 771-74HC04N, by NXP is 30-cents at Mouser)
3 x 0.1uF capacitors
R1 - 10M-ohm resistor
R2 - 6.8M-ohm
R3 - 3.3M-ohm
R - 12 pcs of 100-ohm resistor for the Programming tree. I used 120-ohm resistors which I got free.
2 x "AA" batteries and suitable holder.

Perfboard, wire, supplies, etc.

I've also used sockets for the IC and the LED, which I've found to be quite sensitive to heat.

Step 2: Assembly

Picture of Assembly
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Here is a diagram showing the parts and how they are wired.

The yellow lines are jumpers connecting pins 2&13; 4&11 and 6&9 on the underside. The 0.1uF capacitors are similarly connected under the socket (pin 1&12; 3&10 and 5&8). Make sure the wires do not touch.

The Jumper wires can be inserted anywhere on the 'programming panel' to adjust the brightness and speed of the color changes.

Step 3: The final touch...

Picture of The final touch...
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Now, slip a length of heat-shrink tubing over the LED as a light diffuser, and you are done!

Light on!

More LED circuits are here on my website.
ddolbi11 year ago
Hi, how can you change the frequency of the colour sequence? Say, I want the whole cycle to be completed in 15 seconds until it starts a new cycle.
Also, do you have a clearer schematic?
I am confused about where the other ends of the jumper wires go (the end where it is not connected to the leds), and the four resistors that are in series for each of the 3 circuits. . Do you need each node between the resistors to go to a pin? Because they don't seem to be used
What is the name of that 12 hole/pin socket above the resistors? I cannot find it online.
EET19821 year ago
I have a few DM7404N's. I believe these will work in place of 74HC04's am I right? If you are using only 3 volts, that voltage would be inbtween the min and max voltages. What do you think?
qs (author)  EET19821 year ago
No, the TTL 7404 will not function in this circuit. The CMOS version is required.
EET1982 qs1 year ago
Ok cool. Thank you for answering my question. Ill get the correct chip. And thanks for a great instructable!
kameu4 years ago
Will a 74LS04 work?
qs (author)  kameu4 years ago
Unfortunately, only the HC04 will work. The bipolar transistor versions of the 7404 have the wrong input impedence and operating voltage. 
sgleason1 qs2 years ago
I can use a 4049 in place of the 74hc04 am I correct ?
qs (author)  sgleason12 years ago
In this application, provided you are careful about the voltages and pinouts (they're VERY different!), the 4049 can be substituted.
sgleason1 qs2 years ago
Alright thank you, i know that the 4049 pinouts are different, but what do you mean about voltage, do you use 5volts, because the 4049 can handle that, and what is the point of the 3 different resistors, i was going to use 3 10m ohm resistors, what will it change?
qs (author)  sgleason12 years ago
The 4049 can handle higher Vs but the 3v to the LEDs is at the absolute low end of its operating range. The 3 resistors are chosen to maintain a constantly changing cycle of colors. If they are too close (or the same), the color variations will be EXTREMELY slow, probably in the minutes.
sgleason1 qs2 years ago
alright i just stiched this together using 2 10mohm resitors, the only thing is they are all channging at a desirable rate, but they only change on and off, they dont fade, when i put more or less capacitance in they just stay lit, how would i get the fade effect?
qs (author)  sgleason12 years ago
Ahh, in the circuit, there should be a 500uF (up to 3000uF, 6v or greater) caps going from the Cathode of each of Red, Green and Blue to the Anode. So you would need three such capacitors ... Sorry, the images got changed and I never noticed.
thebanano3 years ago
hallo again...
could that be the speed and the brightness controller is change with a dial/pot?
qs (author)  thebanano3 years ago
You could replace 3 of the 100-ohm resistors with a 1k pot (you'll need 3 pots, 1 for each color), but the effects are not much better.
thebanano3 years ago
hallo qs..
nice work again...

by the way, i want to know that, if can i use 3 (rgb) single 3 mm led for replacing the led that you are using?
it is hard to find that superflux led on my little town,

sorry for my english...
qs (author)  thebanano3 years ago
As long as they are 20mA LEDs in a "Common Anode" form, they will be fine.
Will this make a smooth slow transition between colors or does it quickly change colors?
qs (author)  Electroinnovation3 years ago
This is a pseudo-random circuit so the light changes and times on are not fixed.
However, with the values used, the times are in the 1/4 to 1 second range.
Okay thanks
just smile3 years ago
does the circuit reset itself and start the sequence again.
qs (author)  just smile3 years ago
Yes, the lights cycle continuously.
skyhell20093 years ago
why this circuit must have 12 pcs of 100-ohm resistor..??
qs (author)  skyhell20093 years ago
The resistors control the brightness and cycle speed of each primary color.
KDFAN4 years ago
How could you wire it so that you could connect multiple LED's in a row. Would you have to connect more BLC (Basic Logic Chips)?
mischka4 years ago
Very cool circuit, i like the way people use logic chips.
fupersly4 years ago
Hey qs - little confused - does this circuit actually change colors as a function of time?  Or is it a fixed color you program via setting the jumpers?  The hex inverter oscillators I've seen are a fixed so I cannot figure out from the description how the device would change frequency of the R,G,B leds over time in order to cycle through colors.
qs (author)  fupersly4 years ago
The hex inverters form 3 separate oscillators each controlling a primary color LED, making them shuffle through all color combos automatically.

The jumpers change the brightness of each primary to adjust the combined colors.
fupersly qs4 years ago
 Each oscillator runs at a fixed frequency?  The color changes are due to the oscillators running out of phase?

Sorry - almost there to getting it!
could you send me two separate pics of the schematic and board?
qs (author)  Sagar Gondaliya5 years ago
Schematic added, step (2) above...
Cool little project. Basic logic chips are fun to work with, and a great way for people to get started in electronics. Also, I have to say that that picture with the sketch overlay looks awesome, and really helps to explain it in a way that just a picture of the board and just a sketch might not.
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