A Rainbow LED

[xxxxxxxxxxxxxx]

Hi all, I have searched the net to no avail. I am after a circuit that will fade through all colours using an RGB LED. I cannot have a PIC Micro controller. I know that I can use op amps in a circuit, but I want it to be simpler... If anyone knows of or has any circuits or circuit ideas, they are greatly appriciated.

Thanks a lot!
mike

 

[Andy1845c]

Something like this?
https://www.led1.de/shop/index.php?cPath=48_26&language=en

 

[HarveyH42]

I don't think there is a better way. Op Amps give the best display (fuller spectrum, a little randomness). One chip (LM324), three capacitors (220 uf), and nine resistors, three transistors (2n3906).

 

[xxxxxxxxxxxxxx]

Your circuit sounds simpler than mine. Here it is:

 

[xxxxxxxxxxxxxx]

hey andy, thanks for the thought but i have to be able to control it

 

[audioguru]

I made some fading LED projects that shine brightly on the ceiling at night.
They use opamps as oscillators and as integrators to make the slow triangle waves.

Each oscillator is at a slightly different frequency from the other two so that the three colours appear randomly and at differing levels which makes every shade of every colour.
Occasionally they are all off making black, and occasionally they make pure white.

 

[xxxxxxxxxxxxxx]

Sounds really neat. Got a schematic by any chance?

 

[xxxxxxxxxxxxxx]

Hi again. Just found this on the net (attached) as you can see, i want to get rid of one of the LED segments, and the extra LED. I assume the quick alteration will work fine, and i also assume the extra LED is just acting as a diode/power indicator. Do you guys agree? Is there anything i've missed? Thanks a lot.

 

[audioguru]

Hi Mike,
My fading LEDs circuit is similar to the one Bill Bowden made on his website called Fading Red Eyes or something like that.

The circuit you posted is unusual because the Extra LED #5 is used as a voltage regulator for the 74HC14 IC. It should be a green, white or blue LED because a red LED has a voltage that is too low to power a 74HC14 IC.
The L339 IC has a minimum output current of only 6mA so if you get an LM339 at its minimum then the LEDs will be fairly dim.

 

[BeeBop]

I just caught a link in the micro section, to this:
**broken link removed**

Perhaps that is what you were looking for?

 

[lord loh.]

Those do not seem to offer any control over the RGB...

There seems to be an in built chip and oscillator.

 

[lord loh.]

sorry... i WAS QUOTING

Something like this?
https://www.led1.de/shop/index.php?cP...26&language=en

 

[xxxxxxxxxxxxxx]

yeah, im after somthing that i can completely controll, but no PIC

 

[xxxxxxxxxxxxxx]

Auidoguru,
Hmmm thanks. I didnt realize that. It doesnt sound too fantastic... should I stick with my original? (posted earlier)

 

[HarveyH42]

I attached a PDF of Bill Bowdens fading circuit. It explains how it works, and things you can change. You will need 6 op amps, if you want to control each RGB color individually, or to reduce part count and board size you can cross-fade two colors. I used 220 uf capacitors for a much longer fade.

It doesn't take long to breadboard, parts aren't too critical. So you can use what's on hand or experiment. You only need one voltage divider, and can be shared with the other 1 or 2 colors. Adding a pot to control the rate isn't needed, component tolerances will give you a slightly different frequency for every triangle generator, but might be nice if you want to make one color dominate.

 

[xxxxxxxxxxxxxx]

Thanks very much guys. It is now fully working on my breadboard. I cant show you a movie because the forum doesn't accept it... maybe a suggestion for the moderators...
best regards+ thanks again
-mike

 

[HarveyH42]

You can ZIP the movie, post in on YouTube and link to it. I think movies were omitted to save file space and bandwith, which keeps web costs down and improves access speed at the server.

 

[Hero999]

I can't see them allowing videos here due to the space restrictions so your best bet is to host it somewhare else, like YouTube.

If it's a short film then you could change the extension to .pdf then ask people to rename it when they download it.

In my opinion limiting the extensions that can be posted is a silly idea, file types should be identified by their content rather than extension.