There are some clear plastic pens around, being given away as premiums, They contain Red, Green and Blue LEDs that slowly turn ON and OFF, creating amazing color combinations.
What sort of LED controls can fit into such a small space?
Thanks for any help in finding out how this is done.
Bob snipped-for-privacy@yahoo.com
If I were wanting to do that I would use a hex pack schmitt invertor and feedback R with C down to deck but these pens probably use a small ASIC that is made by the millions under a bit of expoy.
I believe that you can buy (probably only a million at a time) a LED with integrated color changing. All you do is supply power.
Can buy one-off. Electronic Goldmine's had them for a while. See:
$3.25 per. Good price if you don't need to specify how the effect looks, and considering the cost and size of building a similar effect.
Can't imagine anything I'd want to use this for. Maybe wait until the price goes below $1.00 and make a ball of about 25 of them, and give to the nearest college student.
Easy enough, just obtain a cheap LCD car clock and replace the backlight bulb with suitably modified LEDs (RGB) connected to a colour changing circuit usign a PIC, like at :-
Naah, I was meaning each individual segment at once. There's got to be a market.
As others have said, it's probably an ASIC, but you can get microcontrollers in
8 pin SMT packages that can be programmed easily to achieve this result. You just need three PWM outputs and some code that cycles in values for the 'compare' of the PWM counter for each LED. The hardest part is getting a nice color effect because you are dealing with human perception. If you cycle from brown to gray to white it's not gonna look good.
LED "readerboards" have been doing this on a per-pixel basis. Red/yellow/orange/green for decades. Now that we have blue, the full spectrum is available.
Greenweld have some colour cycling pens for 3.95 each :)
-A
I've just bought one from
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