On Fri, 18 Dec 2015 15:43:43 -0800, dr.s.lartius wrote:

On Thursday, 17 December 2015 16:23:51 UTC, Johnny B Good wrote:
On Tue, 15 Dec 2015 13:31:43 -0800, dr.s.lartius wrote:


Some respondents wrote about buying a digital wattmeter - surely not
the type of advice for news:uk-d-i-y, since one can make a digital
wattmeter from the sort of electronic components that became
available a generation or more ago.

Human or technology 'generations'? :-)

Human.

Most DIYers think it's sufficient to buy their tools 'ready made'
rather
than design and build their own DMMs or digital watt meters, especially
when it's likely to cost more just to buy the parts than to buy a
suitable 'off-the-shelf' ready made test meter (£9.99 in the case of
the N67FU I recommended as suitable to making such measurements).
You're talking about "Extreme DIY", a branch of the hobby that most
contributors here would regard as a completely OTT approach to the
gentle art of DIY. :-)

Agreed. The components in question must have cost well over £9.99 in

And, then some! Inflation alone would make it the equivilent of £100 in
the early to mid 80s but it would likely have cost five to ten times more
again simply because the electronic components were so relatively costly
at that early stage of the game.

the money of those days, let alone the auxiliary equipment. But the
accuracy greatly exceeded that of the N67FU. But maybe I can get an
N67FU using someone else's shoe-leather.

Such extreme accuracy (better than a tenth of a watt) would simply be
wasted in such an application as this. I can be confident that, unlike
the 'affordable' sub ten quid 'energy monitors being sold by Aldi (the
infamous DEM1379) and a similar unit from "Machine Mart" a decade or so
ago which could show anything from zero to 20 watts on a 10 watt router
or cable modem load, the N67FU *does* correctly read[1] to within a tenth
of a watt, even on sub 2 watt smpsu wallwart loads since the readings
correlate to within a tenth of a watt as best as I can interpolate the 2
watt graduations on the mirror backed 100W scale of my trusty Metrawatt
analogue watt meter[2] when using a jeweler's loupe. Trust me on this, I
have the means to cross check without reliance on potentially suspect
electronic reference measuring kit. :-)

[1] After my disappointing experiences with cheap 'digital watt
meters' (which tarred all such 'affordable' digital energy monitors for
the next decade afaiwc), I was flabbergasted at the unexpected accuracy
of this energy monitor (aka digital watt meter) as I was, likewise with
its slightly more expensive cousin, the 2000MU-UK (an anglicised "Kill-A-
Watt" for those of the American persuasion). For once, it made a pleasant
change that the 2 or 3 quid each that I spent in my local flea market
*wasn't* a total and utter waste.

[2] I bought this rather nice watt meter at a radio ham rally nearly
thirty years ago. The 35 quid asking price almost put me off (I couldn't
haggle the trader down) but I knew I was looking at something almost
unique in the world of electrical measuring instruments so I 'squandered'
my 35 quid without too much 'soul searching'.

I knew such watt meters were pretty scarce but only discovered, after
googling for more info on this meter just a few years back, that they are
in fact, as rare as "rocking horse ****"(tm).

Gone at last, were the days when I could only guess at the power
consumption of various electrical and electronic mains powered
'appliances'. However at that time, I didn't realise just how useful a
diagnostic aid it was going to become in the art of diagnosing and
repairing desktop and laptop computers when I eventually quit my 'day
job' to build, sell and repair PCs 'full time'.

--
Johnny B Good