[Lab] Open Question: Dumbest Thing You've Done While Making

[Richard Guy Briggs]

On Mon, Jun 24, 2013 at 04:53:04PM -0400, Jason Cobill wrote:
> That's amazing! I had no idea the uO solar car generated that much current!
> What kind of motor was all that power being used to drive? I was under the
> impression it was a tiny motor running at high RPM and geared down for
> torque.

It was a Uniq Mobility 10kW motor.  That motor/controller combination
wasn't nearly as effective at shorting out the battery pack as a small
gold ring.  ;-)    Much of the competition was using Solectria motors at
that time.  Within about 5 years, pretty much the entire field had
switched over to in-wheel motors made by New Generation Motors (NGM), a
company founded by a number of George Washington University solar car
team members.

> Zot's a pretty cool nickname, though. ;)

It makes me think of the "BC" comic strip...  (I say this as I watch a
huge black cloud criss-crossed by jagged white lines completely fill my
large west-facing 4th-floor window at UQO on Tache in Gatineau.)

>    -Jason Cobill
> 
> On Mon, Jun 24, 2013 at 4:49 PM, Richard Guy Briggs <rgb at tricolour.net>wrote:
> > On Mon, Jun 24, 2013 at 04:00:51PM -0400, Jason Cobill wrote:
> > >    Experiments gone wrong? Tools gone out of control? What's the dumbest
> > > thing you should have caught before you nearly set your house on fire?
> > What
> > > did you learn from it?
> > >
> > >    Me first: I plugged in a table saw without checking the switch first -
> > > it was on. And it was covered in 2x4s and sheetwood scraps, which it
> > > proceeded to launch across the garage and nearly take out a window.
> > >    It _should_ have been off, but I _should_ have checked. So now I
> > check.
> > > Every. Time.
> >
> > Oh, this one's easy.  ;-)    I have two related to electricity.
> >
> >
> > 1)  When I was about 10 I had a power transformer that I had taken out of a
> > wood-cabinet vacuum tube TV set.  I had learned to solder when I was about
> > 8.
> > I knew which side was the primary and I wanted to test the secondaries.  I
> > knew
> > they would be high.  I had a cheap analog multimeter from Radio Scrap with
> > a
> > 750V rating.  I carefully attached and shielded the primary wires to a
> > standard two-prong plug.  I was sitting on my bed (so no danger of
> > grounding out, plus it was an isolated secondary).  I pinched one
> > secondary wire with the meter test lead, then grabbed the second test
> > lead and went to pinch it with the other secondary...  (It was about 350V.)
> >         I haven't done that ever again!  Now I used insulated leads.
> >
> >
> > 2)  In my last year of Electrical/Computer Engingeering at U of Ottawa,
> > I was working on the U of Ottawa solar rayce car RALOS-II, wiring up the
> > main power backplane of the car (I was the Electrical Systems
> > Co-ordinator) working on some low-voltage wires on one card that
> > happenned to be facing a high-voltage, high-current card connected to 7
> > car batteries in series (90VDC, 1000A?). As I pulled my hands away from
> > my work something sparked.  Naturally I pulled back, jamming my family
> > gold ring into the high-voltage card.  Once the sparks stopped, two of
> > my fingers were black.  After a quick throw of the main power switch for
> > the car to avoid any further incident, one of my teammates packed me off
> > to the hospital to clean things up.  On the way to the hospital, I was
> > babbling with all the wire cross-sectional diameters, materials and
> > resistances per metre still fresh in my mind, calculating that must have
> > been a 100kW arc welding burn.
> >         I was lucky.  I still have all my fingers, but one has an
> > interesting ring-shaped scar (that was 20 years ago this month) and the
> > bloodstone with the family crest in the ring cracked.  I thought of
> > getting it repaired, then decided to leave it as a reminder.  I was very
> > lucky it didn't instead hit the iron ring on the adjacent finger that I
> > had earned not 2 months prior.  Gold is a much better conductor, so it
> > didn't heat up much compared with the other parts involved.  The two
> > one-inch spade terminals on the card along with 1/2" PC board traces
> > vanished.  I had to check a second identical card to find out what was
> > there.  I earned the nicname "Zot" for that one...
> >         I now remove my rings when working with high voltage/current.
> >
> >
> > I still love electricity!  :D
> >
> >
> > >    -Jason Cobill
> >
> >         slainte mhath, RGB
> >
> > --
> > Richard Guy Briggs               --  ~\    -- ~\            <
> > hpv.tricolour.net>
> > <www.TriColour.net>                --  \___   o \@       @       Ride yer
> > bike!
> > Ottawa, ON, CANADA                  --  Lo_>__M__\\/\%__\\/\%
> > Vote! -- <greenparty.ca
> > >_____GTVS6#790__(*)__(*)________(*)(*)_________________
> >

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	slainte mhath, RGB

--
Richard Guy Briggs               --  ~\    -- ~\            <hpv.tricolour.net>
<www.TriColour.net>                --  \___   o \@       @       Ride yer bike!
Ottawa, ON, CANADA                  --  Lo_>__M__\\/\%__\\/\%
Vote! -- <greenparty.ca>_____GTVS6#790__(*)__(*)________(*)(*)_________________