Not sure how this circuit works?

[fuper]

Was checking out this project:

RGB LED Color Sequencer - without a Microprocessor

The author says that it cycles through various colors. It uses a hex inverter for form 3 oscillators, one for each led.

From looking at the schematics I cannot see how it would "cycle" through colors, namely because outside of setting some jumpers on the board, the frequency of the oscillator is fixed.

The only thing I can think is perhaps there is color variation due to the oscillators being out of phase?

My attempts to simulate the circuit in circuit maker have failed [frustrating!] so far so I thought I would ask.

 

[dougy83]

Do you have to be a member of that site to see the schem? Well I'm guessing that you're right enough about the oscillators being "out of phase" and creating the different colours. It's actually the frequencies of the oscillators will be different due to component tolerances therefore you'll get all the 8 possible colours displayed over some period of time.

 

[audioguru]

The three oscillators simply turn on a colour then turn off the colour at different frequencies. They do not gradually brighten and gradually fade, they just turn on and off.

Sometimes all three LEDs will be off. Sometimes only one colour will light. Sometimes two colours will light and add to make a 3rd colour. Sometimes three colours will light and add to make a 4th colour.

Since the oscillators are at different frequencies then the pattern will appear to be random without repeats. But if you look at a single LED you will see it turning on and off.

I made some Mood Lights that use triangle-wave oscillators to slowly brighten and slowly fade three colours at different frequencies. They add to make millions of slowly changing colours and brightnesses.

 

[fuper]

Instructables

Do you have to be a member of that site to see the schem? Well I'm guessing that you're right enough about the oscillators being "out of phase" and creating the different colours. It's actually the frequencies of the oscillators will be different due to component tolerances therefore you'll get all the 8 possible colours displayed over some period of time.

Ya you have to be a member. They don't spam thankfully. I'm not big on their website, its really slow for me.

I've attached the schematic.

it sounds like from other comments it is due to the different frequencies you get permutations. Not sure if its technically out of phase [might only apply to same frequency signals technically speaking]

Thanks again guys for sharing1

 

[fuper]

What kind of circuit was that?

The three oscillators simply turn on a colour then turn off the colour at different frequencies. They do not gradually brighten and gradually fade, they just turn on and off.

Sometimes all three LEDs will be off. Sometimes only one colour will light. Sometimes two colours will light and add to make a 3rd colour. Sometimes three colours will light and add to make a 4th colour.

Since the oscillators are at different frequencies then the pattern will appear to be random without repeats. But if you look at a single LED you will see it turning on and off.

I made some Mood Lights that use triangle-wave oscillators to slowly brighten and slowly fade three colours at different frequencies. They add to make millions of slowly changing colours and brightnesses.

I know a few basic circuits to build triangle-wave oscillations, using a 555 or a couple of opamps. Would something like that accomplish things?

I've found [perhaps helpful to other begineers] fiddling with music and or RGB leds is a great way to learn electronics. You get instant gratification and it really pushes you to learn.

 

[dougy83]

I know a few basic circuits to build triangle-wave oscillations, using a 555 or a couple of opamps. Would something like that accomplish things?

Yep. It would.

 

[audioguru]

A dual opamp makes perfect triangle-waves. Look in Google for Fading Red Eyes. The timing capacitor should be non-polar (two electrolytics back-to-back).