Date   : Tue, 11 Aug 2009 20:42:34 +0100
From   : philpem@... (Philip Pemberton)
Subject: Tales of woe and stupidity

Rob wrote:
> Both transistors blew up!  Bits of plastic flew off across the room...
>  On reflection, I guessed that these big hulking relays probably drew
> a little more current than the cheap transistors in this kit were
> designed to switch ...

More likely the back-EMF from the relay coil went looking for a path to 
ground... and found the transistors.

Big coil = large back-EMF = big bang if you forget the snubber diode.


> So yes, I think they were right when they said it had "blown up".  The
> poor girl whose feet it had been beside must have been scared out of
> her wits.. And we never laughed again when a customer said that to us
> ...

I'll bet!

Ever seen a lithium-ion battery pack go up? They go up like miniature 
rockets. Nice to watch... from a safe distance.

Who needs model rocket motors, just use a Li-ion!


Actually, I'd rather like to see that Jeremy Clarkson show where he 
figured out a really quick way to cook Christmas lunch, and plate it up. 
Using a spud gun.

"Bit o' hair spray... There we go. Turn the gas on, and... we... retire 
to a safe distance..."

*BOOM*

:)

-- 
Phil.
philpem@...          
http://www.philpem.me.uk/