Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!stc!axion!news
From: BCOLLINS@zaphod.axion.bt.co.uk (Bill Collins)
Newsgroups: sci.electronics
Subject: Re: Zap, fry, and sizzle
Message-ID: <1990Feb26.172532.21678@axion.bt.co.uk>
Date: 26 Feb 90 17:25:32 GMT
References: <1990Feb24.225351.8797@chinet.chi.il.us>
Sender: news@axion.bt.co.uk
Reply-To: BCOLLINS@.axion.bt.co.uk
Organization: British Telecom Research Labs
Lines: 32

From article <1990Feb24.225351.8797@chinet.chi.il.us>, by darus@chinet.chi.il.us (james wygralak):

> 
> Another note of caution: Beware of shrapnel from exploding capacitors.
> 

Way back in my schooldays, when I was first playing with radios, I bought
an ex-army communications receiver, which needed an external power supply.
Since the original ran off a vehicle battery, I knocked up a "cheap and
cheerfull" power supply from my spares box to run it from the mains.

All worked well until the fatefull day when I disconnected the power supply
to use the LT heater output for another use. I forgot that off-load, the
voltage on the HT output would rise from its normal 200v to about 400v ...
(I had used a simple voltage dropper arrangement from a higher voltage
transformer)

Unfortunately, Murphy's Law decreed that the (large) smoothing capacitor
was only rated at 250v ...

After a while there was an almighty explosion, and the end cap blew off
the capacitor with such force that it dented the tin-plate chassis that
it was mounted in. It also created lots of evil-smelling smoke and covered
the room in tiny scraps of waxy tin foil. This is not to be recommended :-) :-)

(Since I had the receiver in my bedroom, my parents were none too pleased
about it either ... )



Regards,
	Bill.