Cautionary Tales of Power

When doing an LED electronics project, there seem to be three big “P”s that have to be tackled:
1. Pixels (which ones, how many, what configuration?),
2. Programming (what do I want, and how can I do that?), and
3. Power (how much, from where, and how do I distribute it?)

And people (by which I mean: perpetual newbies like me) tend to do them in that order: first wire up some pixels, then program them, then figure out how to power it all for real.

And of course, this often leads to a problem where you get stuck between steps 2 and 3, where you have your creation sort of up and running on the lab bench — but now there’s this little problem of how to power it, and you have to go back and rethink and rework other parts of the project to accommodate the power situation.  So it’s worth planning for power from the start — which is easy to say, but hard to do!

What could possibly go wrong? (A list)

So what happens if you don’t plan for power? Well, here are some power problems that I have personally had. How many of these can you diagnose just from the description?  (“Failure to plan” is a nice catch-all phrase here if you get stuck.)

  • Hrm, now how do I get power all the way up there?
  • Gee, that’s a long run of wire… but if I use fat wire, it’ll be expensive and heavy and cumbersome. Nah…
  • I’ll use skinny wire, it’s much cheaper… Hey, why is it only reading 4v at the far end? And does anyone smell something burning?
  • OK, I switched to thicker wire, and I’ll just re-use the power connectors from before. Holy cow now the connectors are getting hot!
  • Fine, I’ll switch to these big thick nonpolarized connectors. Huh, that’s odd, it’s not working now. Does anyone smell something burning?
  • For this other wearable project, I’ll use a simple battery holder and regular alkaline batteries… hey… why are the colors so ‘warm’.. no blue? And now no green, too…
  • OK, switching power to one of those ’emergency phone chargers’ that takes AAs and puts out 5v from a USB socket. Hey! Why are the batteries dying so fast?
  • OK, fine, I’ll switch to this lithium battery pack… hey, it said 5000mAh… so why did it stop powering my 5000ma project after only half an hour?
  • How come my WS2811 project works fine from my computer, but then flickers like crazy when I power it from this cheap USB wall power adapter?
  • For this big outdoor project, I’ll use this big, burly 12V lead-acid marine battery. Hey… how come it won’t hold a full charge after the first time I let the lights go all night?
  • Everything was working fine yesterday, before last night’s rain!
  • Everything was working fine yesterday in the cold and snow, so it should be working fine today now that it’s warming up, right?!
  • I think I’m going to switch microcontrollers.  The old one had a power regulator that could handle 12v input.  Hey… do you smell something burning?
  • Why is this power switch getting hot now? And why is it now totally stuck in the “on” position? And … do you smell something burning… again?

So: Plan For Power.

The lesson to learn here is that for basically any real project, calculate and plan the power first.  Before you wire up any pixels. Before you write any code. Just stop for a minute and think about how much power you’re going to need, and where it has to come from, and where it has to go.

Use on-line calculators that will help you figure out how much power you’re going to need, and what gauge wire you’ll have to use given how long your cable runs are going to be.  I also really like the “LEDstimator” app for iOS to help explore some “what-if” values for things like wire gauge.

And above all else… uh… wait… do you smell something burning?


FastLED for the Apple II: Hack to the Future!





The Details

Here are the details of “FastLED6502”:

I don't usually wear plaid.

FastLED6502 at Veracode Hackathon 7

How’s it work?


The Code


This is Crazy


Lanyard-mountable LED throwies







Fire2012: an open source fire simulation for Arduino and LEDs








“Five Elements” light sculpture

After months of work, “Five Elements”, my first full light sculpture debuted this weekend at a private event.  This quick video shows a short clip of each ‘element’; the actual five-element cycle is 12 minutes long, repeating each of the five elements five times each hour.  As with any “version 1.0”, I have a dozen ways I’d like to polish and keep improving it, but I’m happy with it as is, too.

It’s illuminated by 150 RGB LEDs and controlled by an Arduino Uno using the FastSPI_LED library and my own custom code.
The installation at the debut event used a very different diffuser which made the LEDs more visible.  While both were good, I think I prefer this diffuser overall.

Small Scale Solar power presentation

I gave a “learning lunch” presentation on Small Scale Solar power today.  We had a great audience, got great questions, and had fun doing it — despite the definite lack of sunshine to play with today.

The Short Version is this:

  1. Hook a solar panel to a charge controller to a battery.  (There are starter kits with everything.)
  2. Presto: 12 Volt DC power!
  3. Use your newfound power as-is, or step down to 5v USB, or up to 120VAC using an inverter.

60 Watts of solar panels

The slides don’t tell the whole story by themselves; that requires my own personal song and dance routine.  Nevertheless, here they are, with “lite” graphics for fast download: PDF.

Rejuvenating solar garden lights — with nail polish!



Solar garden lights, all 'frosted' over


Nail polish on solar cells?


Using nail polish to rejuvinate solar cells


Rejuvinated solar cells soaking up sunlight


Fully-recharged solar light glowing brightly!



Glowing bubbles?! Yes! …but no.




…nothing.  Blackness.




