Make: Online : PIC USB color changing light

PIC USB color changing light

Ian at DIY Life made a nice tutorial video on RGB color mixing with LEDs on the PIC platform. His circuit throws in a handful of extras, like mic input. While perhaps simpler to do on the Arduino with a BlinkM, this project looks like a good PIC starter. His whiteboard circuit diagram drawing lapse is pretty neat, too. - Link.

Related:
BlinkM - Link.
DIY ambient orb - Link.

Comments

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Posted by: computerwiz_222 on January 26, 2008 at 7:54 PM

why the capacitors on the 7805 and 7812... I usually just hook it up pin 1 input, pin 2 ground, pin 3 out... Is this for reference to ground, I am fairly new to electronics so please enlighten me!

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Posted by: Becky Stern on January 26, 2008 at 9:25 PM

You can do that, and it will normally be fine, but sometimes power supplies can be "noisy," supplying uneven current, so these capacitors, called "decoupling" capacitors, help even out the power: http://en.wikipedia.org/wiki/Decoupling_capacitor

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Posted by: ian on January 27, 2008 at 12:18 AM

I did the same thing for a long time. One day I took a look at the datasheet for a 7805 and it recommended decoupling caps. I've done it ever since. In general, it's standard practice to put a 0.1uf cap between any IC power pin and ground.

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Posted by: John Honniball on January 27, 2008 at 3:32 AM

The reason for the capacitors is "because the data sheet says so", but some people like to break rules like that. In fact, the capacitors are there for a good reason, and it's not just a ploy by the data sheet writers to sell more capacitors! The 7805 (and similar) regulators contain a high-gain amplifier as well as a voltage reference and a power transistor. The high-gain amp can oscillate under certain circumstances, at a very high frequency. It all depends on the inductance of the supply leads. The capacitors make sure it can't oscillate, and thus ensure reliable operation.

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