Valves Book
 

On Sun, 12 Dec 2004 19:01:34 -0000, "Stimpy"
wrote:

Keith G wrote:

*My 'shooting friend' (and jeweller) offered to get me a 'windmill'
for them to keep them wound, at the time, would you believe? (Not
that there were as many as 8 of them at the same time....!! :-)

Oddly enough I was discussing this with a friend this morning. He's looking
for just such a 'windmill'... Any ideas where he could find one?

There's always loads of them on eBay. Use 'watch winders' in the
search field. This morning, there are 31 hits in the UK alone.

They're useful if you have a perpetual calendar watch, but otherwise
of dubious value. I don't use one myself, I just wear each of my five
decent mechanical watches at least once a month.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Valves Book
 

"Don Pearce" wrote in message
...


Apropos of the actual power supply. WIth valve voltages, during
development, I always had biggish resistors wired across the main
electrolytics to ensure that they discharged fairly quickly after
switchoff - about a couple of seconds was my target. These came out
for the final design, of course.

Many old studio amps had these bleeder resistors permanently installed.
220k seemed typical. They dissipated only a couple of watts, which was
negligible in the overall scheme of things, and discharged the 'lytics
well within the time it took the service man to remove the amp from
its rack, and take of the bottom plate.


Iain

Valves Book
 

"Jim Lesurf" wrote in message
...

I have always been much more slow-and-cowardly.

That's the only approach:-)
Whatever your level of experience, Be afraid, very afraid.
It is conducive to longevity:-)

I have a 220V neon across my variac which fires at 70V
- the danger threshold.


If kit has mains, or above
about 50Vdc I am inclined to keep shutting everything down when I want to
move probes about, etc. Slower. But you get time to think about what comes
next, and may live longer to do more thinking. :-)

SS amps do not take kindly to the open end of a croc clip lead making
electrical contact in the wrong place. They tend to fail the smoke
test immediately. Valve amps, despite their much higher
operating voltages, seem to be a little more forgiving.

One of the first pieces of bech equipment I built for myself was a
discharge box on which is mounted a 50W 10k resistor, with a
voltmeter in parallel and a switch to put them in and out of circuit.
It has screw tags (no croc clips!) and is across the reservoir capacitor
all the time the amplifier is open on the bench. After switching off
the amp and switching on the box, the B+ across the electrolytic
drops to a very low potential in a matter of seconds.


I also tend to prefer bench supplies when developing or testing an amp,
and
only connect to the working PSU when doing more protracted tests. Bench
supplies give more safety options, and can also be useful for checking
other effects, etc.

Yes indeed. I bought a 350V 1A Farnell supply just recently for GBP50.
A good investment I thought. It can supply 2A at 6.3V for heaters, and
this supply remains uninterrupted regardless of the state of the HT supply.
The HT has a variable control plus a selector to increase the potential
in steps of 50V, and with HT off, one can safely poke about, assuming
there are no large caps downstream.


y other advice tends to be "pause and think again, and try to work
out what devious ways the kit in front of your has just devised to try and
kill you." This is also what tea breaks are for.

"Valve amps look so innocent and appealing" (quote, my wife:-)

Hmm:-)

Kunniottaen
Iain

Valves Book
 

Stewart Pinkerton wrote:

Oddly enough I was discussing this with a friend this morning. He's
looking for just such a 'windmill'... Any ideas where he could find
one?

There's always loads of them on eBay. Use 'watch winders' in the
search field. This morning, there are 31 hits in the UK alone.

Nice one... thanks

Valves Book
 

"Stewart Pinkerton" wrote in message
...
On Sun, 12 Dec 2004 18:10:37 -0000, "Keith G"
wrote:

When I gave it to him I was buying Rolexes (8 in total*, including a
'yellow
metal'** Day/Date for about a third of today's RRP....) and gave most of
them away and/or traded them up, the only remaining example being the
Submariner that my oldest son still has.

snip

**Not even Rolex have got the brass arsehole to describe them as 'gold'

Actually, they do. The bi-metal ones have to be described as 'yellow
metal' because of the steel/gold combination, they call it 'Rolesor'
these days, but the solid ones were always described as gold, 18ct in
the UK, but they also made 14ct for the US and Asian market (I'm not
sure if they still do), and way back in the '60s they even did 9ct.


Er, no - wrong again, the 'yellow metal'/gold one I had (the bog ordinaire
Day-Date Perpetual Oyster with 'President' bracelet, IIRC) was called
'yellow metal'. I was told by the aforementioned Malcolm Hammond that it was
actually an alloy (to resist rapid deterioration through wear and tear) and
the avoidance of the word 'gold' was to satisfy the various governments in
the countries where they were sold and the ensuant raft of different 'Trade
Description' requirements involving the (possibly sales-damaging) word
'alloy'. May have been BS, but that's what I was told - 'Gold Rolexes' are a
game - you don't really know, you don't really need to know......

(And as naff as 'butch' German cars, IMO.....)


You do not want to get clouted by some rich chav wearing one of these
18ct 'bling bling' monsters, they're fekkin' heavy! :-)


Yes, I know, I had one - I called it my 'quarter pounder' (I have mentioned
this before here a very long time ago) - about the same weight as a
Submariner, actually....

Anyway, I thought the whole point about Chavs is that all their bling and
'designer label' clothing is fake - no?

Valves Book
 

In article , Iain M Churches
wrote:

"Jim Lesurf" wrote in message
...

If kit has mains, or above about 50Vdc I am inclined to keep shutting
everything down when I want to move probes about, etc. Slower. But you
get time to think about what comes next, and may live longer to do
more thinking. :-)

SS amps do not take kindly to the open end of a croc clip lead making
electrical contact in the wrong place.

Nor do some valve circuits. :-)

Fortunately, in both cases this should not be a problem in normal
use.

They tend to fail the smoke test immediately.

Depends on circumstances. The problem with BJT's is the mix of secondary
breakdown, their willingness to die in your service, and a tiny actual
active device.[1] In some cases, though, using a bench supply with limiters
may help avoid immediate trouble. In the end, resistors will release the
magic smoke, though, at the command of either SS or valve... ;-

Valve amps, despite their much higher operating voltages, seem to be a
little more forgiving.

Depends on the circumstances. I've certainly seen smoke, flames, flashes,
and accompanying noises emerge from valve circuits pretty swiftly. Probably
not on the same timescale as secondary breakdown, but still faster than
anyone can leap to the power switch! :-) Hence on a 'human response time'
basis the difference may not always be that significant. And SS devices can
often be cheaper than large valves to replace.

If comparing the safety and reliability of SS devices and circuits with
valve ones, you would need to consider more factors. For example, the
higher sensitivity of valves to mechanical damage, ageing effects, etc.

However, if the design is a decent one, and the units are appropriately
used these things are more of a worry for the development engineer
than the end-user.


Slainte,

Jim


[1] Plus the innocent assumption of the designer that no-one has just
dropped a metal bar into the circuitry. :-) This makes me think of the
old BEAB/BS tests that used to include things like lowering a metal
jewellery chain into the set to see what it might find...

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Valves Book
 

On Mon, 13 Dec 2004 12:43:06 -0000, "Keith G"
wrote:


"Stewart Pinkerton" wrote in message
.. .
On Sun, 12 Dec 2004 18:10:37 -0000, "Keith G"
wrote:

When I gave it to him I was buying Rolexes (8 in total*, including a
'yellow
metal'** Day/Date for about a third of today's RRP....) and gave most of
them away and/or traded them up, the only remaining example being the
Submariner that my oldest son still has.

snip

**Not even Rolex have got the brass arsehole to describe them as 'gold'

Actually, they do. The bi-metal ones have to be described as 'yellow
metal' because of the steel/gold combination, they call it 'Rolesor'
these days, but the solid ones were always described as gold, 18ct in
the UK, but they also made 14ct for the US and Asian market (I'm not
sure if they still do), and way back in the '60s they even did 9ct.

Er, no - wrong again, the 'yellow metal'/gold one I had (the bog ordinaire
Day-Date Perpetual Oyster with 'President' bracelet, IIRC) was called
'yellow metal'.

Check the Rolex website. Aside from the bi-metal 'Rolesor' models, the
yellow (and white and pink) stuff is all called 18 carat gold.

I was told by the aforementioned Malcolm Hammond that it was
actually an alloy (to resist rapid deterioration through wear and tear)

Anything less than 22/24 ct gold is indeed an alloy, usually with
silver and/or copper, and increases wear resistance and general
hardness, but a 9ct gold chain is still sold as 'gold'.

and
the avoidance of the word 'gold' was to satisfy the various governments in
the countries where they were sold and the ensuant raft of different 'Trade
Description' requirements involving the (possibly sales-damaging) word
'alloy'. May have been BS, but that's what I was told - 'Gold Rolexes' are a
game - you don't really know, you don't really need to know......

Sounds like BS to me - the only place where 18ct is seen as
substandard is the Far East, including India.

(And as naff as 'butch' German cars, IMO.....)

You won't ever see me in a Beemer or a Merc, that's for sure!

You do not want to get clouted by some rich chav wearing one of these
18ct 'bling bling' monsters, they're fekkin' heavy! :-)

Yes, I know, I had one - I called it my 'quarter pounder' (I have mentioned
this before here a very long time ago) - about the same weight as a
Submariner, actually....

Musta been a fake then - should be a *lot* heavier than a steel
Submariner, one of which I wore for 14 years. The pukka 18ct President
bracelet alone weighs more than a Sub!

Anyway, I thought the whole point about Chavs is that all their bling and
'designer label' clothing is fake - no?

The rich ones don't know the difference anyway! :-)

And the trainers have to be sparkling white - to show that you stole
them today..................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Valves Book
 

"Stewart Pinkerton" wrote in message
...
On Mon, 13 Dec 2004 12:43:06 -0000, "Keith G"
wrote:


Yes, I know, I had one - I called it my 'quarter pounder' (I have
mentioned
this before here a very long time ago) - about the same weight as a
Submariner, actually....

Musta been a fake then - should be a *lot* heavier than a steel
Submariner, one of which I wore for 14 years. The pukka 18ct President
bracelet alone weighs more than a Sub!


That sounds like absolute ******** to me, but I have to admit I didn't spend
a whole lot of time 'weighing' my watches.....

(Who TF *does*...!!!???)

As to fake, er, I don't think so, especially as Malcolm Hammond bought the
damn thing back off me a year or so later for £500 *less* than I paid for it
with all the composure of a dog on chopped liver when I a) realised I didn't
like it at all (way too naff) and b) needed the proceeds quickly to finish
off a barn I was having built, which had gone over budget....



Anyway, I thought the whole point about Chavs is that all their bling and
'designer label' clothing is fake - no?

The rich ones don't know the difference anyway! :-)

And the trainers have to be sparkling white - to show that you stole
them today..................


You have a curiously detailed ('insider' ?) knowledge of the affairs of
Chavs.....(???)