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.

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.
<p>Thanx...How do we modify to slow and smooth the color changes without deceasing the brightness?</p>
<p>Can I do this with a common cathode instead of common anode rgb led?</p>
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.<br>Also, do you have a clearer schematic? <br>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.
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?
No, the TTL 7404 will not function in this circuit. The CMOS version is required.
Ok cool. Thank you for answering my question. Ill get the correct chip. And thanks for a great instructable!
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Will a 74LS04 work?
Unfortunately, only the HC04 will work. The bipolar transistor versions of the 7404 have the wrong input impedence and operating voltage.&nbsp;
I can use a 4049 in place of the 74hc04 am I correct ?
In this application, provided you are careful about the voltages and pinouts (they're VERY different!), the 4049 can be substituted.
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?
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.
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?
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.
hallo again...<br>could that be the speed and the brightness controller is change with a dial/pot?
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.
hallo qs..<br>nice work again...<br><br>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?<br>it is hard to find that superflux led on my little town,<br><br>sorry for my english...
As long as they are 20mA LEDs in a &quot;Common Anode&quot; form, they will be fine.
Will this make a smooth slow transition between colors or does it quickly change colors?
This is a pseudo-random circuit so the light changes and times on are not fixed. <br>However, with the values used, the times are in the 1/4 to 1 second range.
Okay thanks
does the circuit reset itself and start the sequence again.
Yes, the lights cycle continuously.
why this circuit must have 12 pcs of 100-ohm resistor..??
The resistors control the brightness and cycle speed of each primary color.
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)?<br />
Very cool circuit, i like the way people use logic chips.<br />
Hey qs - little confused - does this circuit actually change colors as a function of time?&nbsp;&nbsp;Or is it a fixed color you program via setting the jumpers?&nbsp; The hex inverter oscillators I've seen are a fixed so I&nbsp;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.<br />
The hex inverters form 3 separate oscillators each controlling a primary color LED, making them shuffle through all color combos automatically.<br /> <br /> The jumpers change the brightness of each&nbsp;primary to&nbsp;adjust&nbsp;the combined colors.
&nbsp;Each oscillator runs at a fixed frequency? &nbsp;The color changes are due to the oscillators running out of phase?<br /> <br /> Sorry - almost there to getting it!<br />
could you send me two separate pics of the schematic and board?
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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