Searcing for a cheap LED breathing IC solution

[vinodstanur]

Hi,
I want to do an LED breathing circuit as a part of a project without any microcontroller. I have many designs , one is a dual opamp based triangular wave generator, another one is a 555 + single transistor based circuit and few more circuits based of 3 or 4 transistors and all are working fine.
But my question is, is there any simpler solution for this rather than putting 8 or 10 discrete components just for making an LED breath? (Breathing of LED means increasing and decreasing the intensity periodically)
I mean, I am expecting a cheap and single chip solution other than a programmable microcontroller. Is there any thing like that?8-O

 

[BradtheRad]

If you want it to be unpredictable, there are noise-generating circuits. I believe they amplify Brownian motion in a diode or transistor or capacitor.

I once had an electrolytic capacitor whose charge went up and down slightly, for no reason, just sitting there. I think it was old and stressed. Chemical action between the foils created a small changing voltage. This sort of thing would make an ideal noise generator for your project.

OTOH you will get predictable breathing from a slow oscillator (eg., classic astable).

You can introduce chaotic action by combining two oscillators at different frequencies. Or use the famous Chua chaotic circuit.

It appears that you can get a continual pulse train from >fewer< components, but you need >more< components to obtain unpredictable action.

 

[vinodstanur]

If you want it to be unpredictable, there are noise-generating circuits. I believe they amplify Brownian motion in a diode or transistor or capacitor.

I once had an electrolytic capacitor whose charge went up and down slightly, for no reason, just sitting there. I think it was old and stressed. Chemical action between the foils created a small changing voltage. This sort of thing would make an ideal noise generator for your project.

OTOH you will get predictable breathing from a slow oscillator (eg., classic astable).

You can introduce chaotic action by combining two oscillators at different frequencies. Or use the famous Chua chaotic circuit.

It appears that you can get a continual pulse train from >fewer< components, but you need >more< components to obtain unpredictable action.

Hi,
I am a bit confused since you are talking about noise generator...
What I am trying to make is a some thing similar to a sinewave or if not possible, a triangular wave or still if not possible a capacitor charging and discharging..... I need to make an LED increase brightness and then decrease and then it continues it... I can make it using discrete components (opams, transistors, 555 ic etc etc etc) but I am searchign for a single chip solution like some chinese chips playing a complete song from a CHIP ON BOAD or similar setup... But it should be available online in bulk....

 

[crutschow]

The only thing that I can think of, that would take fewer parts than the discrete designs mentioned is a microprocessor. The Chinese chips you mentioned are likely some form of microprocessor.

 

[BradtheRad]

Arrange a 555 timer IC as a pulse generator. You can tap for a triangle waveform at the capacitor.

 

[crutschow]

If you want it to be unpredictable, there are noise-generating circuits. I believe they amplify Brownian motion in a diode or transistor or capacitor.
...................................

Typically it's the thermal or shot noise in the device that's amplified. Brownian motion occurs in a liquid and is mechanical motion due to the thermal motion of the molecules in the liquid, not electrical. An ideal capacitor by itself has no thermal noise.

 

[BradtheRad]

Typically it's the thermal or shot noise in the device that's amplified. Brownian motion occurs in a liquid and is mechanical motion due to the thermal motion of the molecules in the liquid, not electrical. An ideal capacitor by itself has no thermal noise.

Yes, you are right. It was my mistake to generalize the various random effects as Brownian motion.

 

[kam1787]

How many LEDs do you hope to drive?

Supply voltage?

 

[vinodstanur]

It seems like there is no such single chip solution, so I am going with discrete components...

Thanks