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In-Reply-To: <731EB49F88B309428FFDDD2423F810E441C377@HERMES4.ds.leeds.ac.uk>
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 <731EB49F88B309428FFDDD2423F810E441C377@HERMES4.ds.leeds.ac.uk>
Date: Sun, 30 Nov 2008 11:05:56 +0100
From: "John RABSON" <john.rabson@wanadoo.fr>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: RE: SDR for 136k / 500k
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Chris, Mike,

Many thanks.  I intended to send directly to Jim, but forgot to change the T=
o: field.  Yes, the colours are as you describe.

Regarding getting the polarity the wrong way round, in the mid-1960s one of=20=
my colleagues was called upon to design a power supply with 12 V output at s=
ome amps.  The output capacitance required was a quarter of Farad made up of=
 25 x 1000 =B5F capacitors connected by busbars.  The prototype came back fr=
om the workshop and he plugged it in.

At point he realised two things: (1) the workshop had got every one of the c=
apacitors wrong way round and (2) the mains switch for his bench was located=
 behind the unit under test.  He walked quickly toward the big red button at=
 the end of the lab but didn't get there quickly enough.  There was a coloss=
al bang and we had a well-decorated ceiling.

73
John F5VLF

*********** REPLY SEPARATOR  ***********

On 29/11/2008 at 09:12 Chris Trayner wrote:

>Hi John,
>
>
>You saw Jim's reply, but
>
>> a grey stripe with a 0 on it and this is adjacent to the shorter of the
>two leads.  If I recall correctly, this is the negative lead,
>
>Is it a rather oval 0?
>The tradition seems to be a grey minus (rounded rectangle) within a black
>oval within a grey band on a black background.
>A case of not quite making up their minds what the colour scheme is? ;-)
>
>You may also find some (for want of a better term) crease lines on the
>exposed metal end of the can. I think these are purposely weak so that if
>it goes it blows there, with little containment (in the explosives sense).
>I can vouch for this, as from time to time one of our students puts one
>wrong way round on the 15V line. They go off with a very satisfying bang!
>... followed by other students crowding round the bench to see what had
>happened. The end of the can shears along the crease lines and the bits
>peel back like petals, allowing fluffy stuff to be ejected fairly
>harmlessly.
>
>73,
>Clank