Saturday, July 16, 2011

I Heart Parts

With freshly minted driver licenses at the ripe age of 16, my uncle handed my brother and I the keys to his 1992 Chevrolet pickup.  Tip-top shape; A+ condition, but after a few years of sweaty football clothes, windows down in the rain, mudding down a river, and a freak incident with ten bags of cereal, tampons and streamers, it shared an uncannily olfactoric relation to a post-apocalyptic locker room filled with moldy towels.

My neighbor at the time had one of those THE Sharper Image THE Ionic Breeze units that made his house smell clean, so we asked if we could borrow it to clean out the stink in the truck.  After plugging it in, we heard the spark of death, followed by an electrical engineer's nightmare: letting the magic smoke out.  Now the truck smelled like the aforementioned grime with a hint of that smell a power tool gets right before you know something bad is about to happen.

**Poof!**

After extensive apologies and a subsequent analytical post-mortem autopsy, we determined that THE Ironic Breeze required a ground plug to keep the high voltage Boost converter reference correct; UL allows lazy manufacturers to leak up to 1mA to ground as part of an onboard reference circuit, which almost certainly saved The Idiotic Brains team the hassle of designing one themselves.  Kids, don't break them ground tabs off your extension cords!

After covertly reapplying the "VOID IF REMOVED" label, we trekked out to THE Snarker Innit and exchanged the still-in-warranty THE Iconic Beat for a new unit.  On our way out the door, we noticed a miniaturized 12V cigarette lighter version, which we snatched up and used until it's untimely death the next time the windows were left down in the rain (a common occurrence; don't let me fool you into thinking we learned our lesson and rolled the windows up).  

Fast forward a couple years and you'll find my brother* and I driving our pickup north on I-25 towards Granby, Colorado, listening to music with the windows down, when all of the sudden THE Stupid Idiot lights up in flames, again releasing the magic smoke.  In a quick motion, I launched the flaming hunk of inferior engineering out the window and then we looked at each other and double-shrugged.  

*note: not 'bro', but my 'brother' (i.e. 'real life doppelganger')... fucking alpha male idiots

Within a week, the stench of truckenstein had returned, so we found ourselves on eBay browsing for a better unit.  A few days later, two AUTO Air units sat at our doorstep, waiting their turn for the gauntlet that was our venerable cigarette lighter.  And they kept working.  And working.  And working.  Rain, sleet and snow didn't phase them.   

And then we went to college and the beastly black truck sat mostly unused.  The smell faded, and when I sold it you would never guess it's former condition.  THE pseudo-Ionic Breeze units fell into disuse and eventually ended up in a drawer somewhere, waiting for that day when they could once again roam the roads spewing out ozonic fumes.  

When my dad's place flooded a few months back, they were two of the few things I kept from all the other crap I recycled, threw out, or gave away.  Today I found them again and decided to see if they still worked.  Rather than plug them into a car's cigarette lighter (I have no car), I kludged them up to a 2.35W solar panel and they instantly sprang to life, humming away in unison.


They sounded louder than I remembered, so I hooked them up to a volt meter and measured 18 Volts, which meant they weren't pulling enough current to keep the panel voltage around the 14V they would see in a running vehicle.

Since I didn't care about using the additional power, I rigged up four 1N4729A reverse-biased 3.3V zener diodes in series across the panel output. 


 In this configuration, no current will flow through the diodes until the voltage reaches 13.2 V (3.3 V * 4 diodes in series).  Unlike a normal diode, which will not allow current to flow through it in the reverse-biased direction until it catastrophically breaks down at a very large voltage, zener diodes will resist current flow until a predefined voltage, at which point they will allow current to flow in a controlled manner until the voltage lowers down to said voltage, at which point their resistance increases such that no current flows.  What this means is that the Zener diode will consume all of the power the panel can generate above 13.2 V.  Note that Voltage is not equivalent to power (i.e. Watts), but I'm foregoing an explanation for the current response curve of a solar panel at different Voltages... 

I felt it was a shame to leave these guys sitting in a box, so I reached back in my brain for a use and remembered these guys generate ozone as they purify the air.  Excited, I rigged the solar panel up to the roof and swung the ionizers down below the roofline to keep them dry.  "Why not generate some ozone and help mother nature out?" I thought.  You're welcome, Mother Earth.  After marveling in my shoddy work, I wondered just how much I was helping regenerate the ozone hole (I was ballparking 0.000000000000000000000001%), so I did some internet sleuthing and uncovered my new contraption's demise:

While ozone up in the atmosphere is good at preventing UV light from burning our buns, low-level ozone is designated as a level 4 OSHA health hazard, causing immediate, long term harm.  After a few more minutes of reading, I got the ladder back out and took down my attempt to green this wonderful planet.


Moral of the story: Knowledge is power.  People are stupid.  Power and stupidity = research.