two fading on and off leds. Out of phase?

[oram]

HI everyone.

I'm unsure of how to explain what i need.

I want a circuit that can osscilate two leds (fading on and off, is this sinewave?). However i want the two leds to be rising and falling at different times, so as one is rising the other is falling (is this out of phase?)

I've had a good look around the internet and haven't found anything that does what i want, or that i don't quite know how to word what i want accurately in the google search.

Any help, advice would be great.

Thanks

[David]

The answer to your questions is a broad yes. In circuit terms, I think the easiest way would be to use what is called a "long tail pair" of transistors with the LEDs in the collector circuits. Feed this with AC at your chosen frequency and you should have the effect you want.

I would recommend that you get some good books on circuit design - I have seen some good ones mentioned on this site.

[oram]

Hi David cheers for your reply. I've been looking at the long tail pair of transistor circuits and I don't quite understand them, or at leat the ones that looked like i might be able to figure out what components are needed. I am confused about the input on the base of the npn, is this from ac? (ground?)

Also the output ( collector?) I have been putting a leg of the led here (+)... but did not know where to put the other leg, is this where you asked me to put the led? I've tried many different configurations to see if i can figue it out but to no avail, as you say I need to get reading them books, maybe this is a bit beyond where i should be right now. Should i maybe begin with a single npn sinewave circuit first? I found this one....

http://members.shaw.ca/roma/twenty-three.html

Cheers

Darren

[David]

The long tail pair diverts a fixed current (set by the tail resistor and the input voltage) between the transistors, which is the effect you want, I think. put the LEDs between the V+ line and the collectors with (say) a 1k resistor also in series. Hold one base via 100k to about 1/2 V+ and vary the voltage applied via another 100k to the other base (Use a pot). Experimentation will be necessary!

Yes, do study the books. Electronics is a fascinating subject, but you must know how to use the different components.