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Re: burning smell

On Sun, Mar 30, 2003 at 05:29:49PM +1000, Ross Cottrell wrote:
> Nathan E Norman wrote:
> >On Sat, Mar 29, 2003 at 12:57:44AM -0800, Vineet Kumar wrote:
> > 
> >
> >>* Pigeon <jah.pigeon@ukonline.co.uk> [20030327 21:15 PST]:
> >>   
> >>
> >>>On Fri, Mar 28, 2003 at 02:23:22PM +1100, Matthew Palmer wrote:
> >>>     
> >>>
> >>>>On Wed, 26 Mar 2003, Pigeon wrote:
> >>>>
> >>>>       
> >>>>
> >>>>>>>If you leave it for a few hours after disconnecting the power, you
> >>>>>>>should be safe. The power supply should have resistors to discharge 
> >>>>>>>the
> >>>>>>>capacitors when they're switched off.
> >>>>>>>             
> >>>>>>>
> >>>>>It SHOULD have, but often does not. If it does, less than a minute is
> >>>>>all you need. If it doesn't, a few days might not be enough. So check
> >>>>>it with a voltmeter.
> >>>>>         
> >>>>>
> >>>>Misparsed as "check it with a volunteer".  Might be a problem if you're 
> >>>>at
> >>>>home or in a small company where a missing luser might be noticed...
> >>>>       
> >>>>
> >>>In electronics labs etc, if someone suddenly says "Catch!" and lobs
> >>>something at you, don't catch it. It's probably a capacitor with a
> >>>nice hefty charge in it.
> >>>     
> >>>
> >>Pigeon, dude ... you've got to find some less hostile friends! ;-)
> >>   
> >>
> >
> >Actually, I think that many people in electronics labs are just this
> >way.  They're very friendly people otherwise :-)

Yeah, it goes with the territory - an interest in hair-raising
(literally or otherwise) technologically-based stunts.

We had considerable fun at the plant-hire company I worked at with the
4kV probe on the portable electrical appliance insulation tester. One
bloke saw stars after testing the minimum safe distance between the
probe and his tongue.

We also got up to other tricks like taping two bolts end-to-end into a
short metal tube with the charge out of a nail gun cartridge in
between the ends of the bolts and dropping this contrivance end-on
onto the concrete floor. Also chasing each other around the racking in
games of what was effectively don't-touch-the-floor tag, except that
instead of touching someone to tag them we shot them with an air pistol.

> >Full disclosure; my dad taught me this trick when I told him we were
> >going to do some experiments at school.

Theoretically or practically? :-)

> When I was a kid, about the time when my father was first teaching me about
> electronics, I charged up an electrolytic capacitor using a hand-cranked 
> 'Megger'
> (Megohm-meter) and managed to zap myself with it.  I must have fallen to 
> the
> floor from the shock; I have no idea how long I was out - all I remember is
> picking myself up from the floor.  A decade or so later I was designing
> offline switching power supplies.
> After my father died, I inherited his electronic/electrical gear, but 
> strangely
> there were no Meggers among the stuff he left behind.  I wonder what 
> happened
> to them.  The nicest thing he ever said to me was "you have that 
> engineering nouse";
> this was after he'd outlined a problem he was having and I'd described a 
> simple
> solution for him.  He's been dead ten years now.

I think it was on my sixth birthday that my father gave me a "sparking
machine": a wooden baseplate on which were mounted a battery,
microswitch, condenser, ignition coil and spark plug. The HT
connection to the spark plug was of the old-fashioned type which
exposed the live parts. Other kids who came to the house used to get
conned into holding the HT connection while I pressed the button.

> Know of any Electronic CAD systems that run on GNU/Linux, preferably Debian?

The source code for Spice can be downloaded from Berkeley, but it
requires considerable hacking to get it to compile, and further
hacking to prevent it segfaulting continually due to calling free() or
fclose() more than once on the same pointer. Unfortunately, I don't
have a working version at the moment. (I'm using PSPICE for DOS which
is really just as good apart from having to run DOS... Anyone know of
a utility to convert models between PSPICE and Spice formats?)

There's a "pcb" package in Debian, which I've looked at briefly and it
seems (a) awkward to use (b) stunted (c) short on documentation (d)
unsuited to 800x600 screen resolution. So I'm still in DOS here too...
There's also a schematic editor "geda", which I haven't looked at as I
can't get out of the habit of drawing schematics on paper, and
probably won't until human interface technology - especially monitors
- gets a lot better than its current state.


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