J. P. Gilliver <G6JPG@255soft.uk> wrote:

[...]
> I don't think I've ever heard of the zigzag type of multiplier ever
> being used with thermionic rectifiers (you'd need several such,
> obviously), so I think they only became practical with solid-state
> rectifiers.

Look up high voltage accelerators in Philips Technical Review. They
used thermionic rectifiers in Cockroft-Walton multipliers with the valve
heaters supplied by H.F. energy circulating through the capacitors.
Very clever.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Angus Robertson - Magenta Systems Ltd <angus@magsys.co.uk> wrote:

> > I once had to "maintain" an Italian gadget that projected film or
> > TV images onto a layer of oil and the reflection was displayed on a
> > cinema screen.
>
> Probably the Swiss https://en.wikipedia.org/wiki/Eidophor
>
> Only way to get bright cinema sized TV screens until LED walls, LCD and DLP
> projectors came along.

The Eidophor was famed for causing a who-does-not-do-what union dispute
in the BBC. Nobody wanted to work it, the video technicians union
claimed it was lighting and the lighting union claimed it was video.

One of the problems was the ionic bombardment of the cathode, which
could fail randomly (often just before transmission). Spare cathodes
could be swung into place without running down the vacuum, but the whole
cathode assembly would then have to be replaced before it could be used
again. Opening up the tube, replacing the cathodes and then pumping
down to vacuum again took several hours - with the possibility of leaks
each time.

Nobody wanted the responsibility of it failing on transmission.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <kk6s7gFaskvU4@mid.individual.net> at Thu, 17 Aug 2023
16:21:22, Andy Burns <usenet@andyburns.uk> writes
>J. P. Gilliver wrote:
>
>> Andy Burns writes:
>>
>>> Angus Robertson wrote:
>>>
>>>> Probably the Swiss https://en.wikipedia.org/wiki/Eidophor
>>>
>>> Or a G.E Telaria
>>
>> Weren't there some systems that used lasers, and either a mirror-drum
>>or coil-controlled mirrors?
>
>Probably came later, these two are 1940/50's and 1970/80's
>
>> (Or was the Telaria such?)
>
>It also used an oil film, Mike Harrison got hold of one and tore it
>down as he does with lots of other "electric stuff".
[]
Ah. I thought a system had been tried with lasers and a spinning drum
with (presumably) 576 very precisely-angled mirrors. Maybe it was mooted
but modulating the lasers proved problematical.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Look at those early black-and-white episodes of /Coronation Street/;
like Ibsen in an flowered pinny. - Iam McMillan, RT 2020/2/22-28

On 16/08/2023 08:25, Ashley Booth wrote:
> J. P. Gilliver wrote:
>
>> As it's the only such prog. for decades, I don't want to criticise it
>> too much. This week's does feature some actual electronics - a valved
>> wireless, and an '80s boombox (as well as a food mixer that has more
>> electronics than I expected).
>>
>> But basic TV presentation? This component has failed, here's the
>> replacement - out of focus? hardly any close-ups? A whole second to
>> look at them, if we're lucky? Also, the odd block diagramme wouldn't
>> go amiss - not enough to frighten the children/horses, but none at
>> all is too few. The voice commentary actually isn't bad at explaining
>> things (to a near-zero knowledge audience anyway), but would
>> certainly benefit from some visual aids. (It has good AD.)
>>
>> One wonders who the prog. is actually aimed at. I'm sure a lot of it
>> is entertainment only - here are some funny men (they have all been
>> men so far, I think) who fix things as a sort of strange hobby;
>> however, it does give some information on how things work. But not at
>> people like us.
>
> I'm amazed at the prices. ?500 for an old boom box!!

I was impressed by the prices for the Commodore+Spectrum combo in the
previous episode. They were expecting £100's but got £10. Except they
didn't, as there was £5 for the new switch for the Commodore. So £5 profit.

I've never seen a portable player that plays LPs. I remember the ones
that played 7" singles (vertically) around 1970. And there were ones in
cars. Then Musicassettes came in and everyone used them in their "ghetto
blasters".

I'm not sure who this programme is intended for either. Just a nostalgia
trip I think. I liked the way they summarised the functions of
capacitors in radios as coupling, decoupling, smoothing and tuning.
(Wow! coupling /and/ de-coupling!)

--
Max Demian

Max Demian <max_demian@bigfoot.com> wrote:

[...]
>I liked the way they summarised the functions of
> capacitors in radios as coupling, decoupling, smoothing and tuning.
> (Wow! coupling /and/ de-coupling!)

That's always been a difficult one to explain to beginners. If it goes
to earth, it can decouple two circuit that share the same power supply
because it couples the voltage variations to earth.

It is a bit like a nut and bolt, it can fix two items together so that
movement of one is transferred to tha other - or it can stop one of them
moving if the other one happens to be firmly fixed.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <uc05pm$200ln$1@dont-email.me> at Mon, 21 Aug 2023 18:10:15,
Max Demian <max_demian@bigfoot.com> writes
[]
>I'm not sure who this programme is intended for either. Just a
>nostalgia trip I think. I liked the way they summarised the functions

Except I'd say it gives _slightly_ too much technical detail for just
that.

>of capacitors in radios as coupling, decoupling, smoothing and tuning.
>(Wow! coupling /and/ de-coupling!)
>
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Old soldiers never die - only young ones

In message <1qfttdw.1v3yvhizoejzcN%liz@poppyrecords.invalid.invalid> at
Mon, 21 Aug 2023 18:49:07, Liz Tuddenham
<liz@poppyrecords.invalid.invalid> writes
>Max Demian <max_demian@bigfoot.com> wrote:
>
>[...]
>>I liked the way they summarised the functions of
>> capacitors in radios as coupling, decoupling, smoothing and tuning.
>> (Wow! coupling /and/ de-coupling!)
>
>That's always been a difficult one to explain to beginners. If it goes
>to earth, it can decouple two circuit that share the same power supply
>because it couples the voltage variations to earth.
>
>It is a bit like a nut and bolt, it can fix two items together so that
>movement of one is transferred to tha other - or it can stop one of them
>moving if the other one happens to be firmly fixed.
>
Good analogy.
>
Another concept is the relativity of signals. I can't remember where I
was confused and what enlightened me: I think it was that US circuits
(or "schematics") tended much more to _not_ draw a line along the bottom
of the signal flow path, instead just liberally sprinking earth or
ground symbols. I think it might have been a car wiring diag. that
caused me to see the light. (When car wiring tended to actually _use_
the chassis more.)
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Old soldiers never die - only young ones

J. P. Gilliver <G6JPG@255soft.uk> wrote:

> In message <1qfttdw.1v3yvhizoejzcN%liz@poppyrecords.invalid.invalid> at
> Mon, 21 Aug 2023 18:49:07, Liz Tuddenham
> <liz@poppyrecords.invalid.invalid> writes
> >Max Demian <max_demian@bigfoot.com> wrote:
> >
> >[...]
> >>I liked the way they summarised the functions of
> >> capacitors in radios as coupling, decoupling, smoothing and tuning.
> >> (Wow! coupling /and/ de-coupling!)
> >
> >That's always been a difficult one to explain to beginners. If it goes
> >to earth, it can decouple two circuit that share the same power supply
> >because it couples the voltage variations to earth.
> >
> >It is a bit like a nut and bolt, it can fix two items together so that
> >movement of one is transferred to tha other - or it can stop one of them
> >moving if the other one happens to be firmly fixed.
> >
> Good analogy.
> >
> Another concept is the relativity of signals. I can't remember where I
> was confused and what enlightened me: I think it was that US circuits
> (or "schematics") tended much more to _not_ draw a line along the bottom
> of the signal flow path, instead just liberally sprinking earth or
> ground symbols. I think it might have been a car wiring diag. that
> caused me to see the light. (When car wiring tended to actually _use_
> the chassis more.)

Drawing circuit diagrams so they explain what is going on is as much an
art as a science. Suppose you have a sensitive amplifier where earth
circulating currents could introduce spurious signals between sections
that are both nominally connected to 'earth', so the earth line is
really part of the signal path.

I tend to represent this either with diagonal earth connections to one
single point or with a separate section of earth line for that section
of the amplifier, offset vertically and joined to the rest with a
thinner vertical line. I have also seen it done by lettering or
numbering the 'floating' earth points, but the intention is not
immediately obvious at a glance and it takes time and effort to compare
numbers.

Where 'floating' earth points can be a great help is along the + line at
the top of the diagram. That saves a lot of vertical lines from
decoupling capacitors down to the earth line, threading their way
between signal lines and components. Alternatively they can be shown
connected to a short section of earth line near the top, with one
vertical down to the main earth line.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

On 16/08/2023 11:32, Brian Gaff wrote:

> No that was right. Last week with the Spectrum, they did not mention quite
> why ram chips fail. It was because Uncle Clive bought duff chips with only
> half the chip working and then put links in the pcbs to use the good half.
> This tended to mean that the quality of the working bit could be said to be
> suspect. Certainly most of the ones I had had some stock faults. Ram was the
> main one, Then I think it was TRY, which was a little psu to make the p-5v
> from the +5 coming out of the regulator, If this failed badly it could take
> a ram chip with it, and failed to power add ons like vtx 500 modems and the
> like. The ULA often was damaged if things were pulled off the port while it
> was powered up, along with tr4.

Some Spectrums had an IC soldered upside down on top of another chip.
Commonly referred to as the "dead cockroach" model.

> On the tech level of the show, yes I agree. They never said what he did to
> clean up the vintage radios volume control, as from experience there was no
> other course but to replace it, since the leaky capacitors around there
> would have put DC on it and that is a good way to wear it out.

A spot of switch cleaning fluid usually does the trick.

I thought DC through the volume control just caused the crackling rather
than damaging the track, usually found with combined on/off/volume
controls, as there will be a current flowing through the control to
charge the coupling capacitor just after switching on.

> I was surprised the double sided record deck was fine after a new stylus a
> clen up and new belts. Its been my experience with another one of those that
> the thing tends to have major issues with tracking a whole album due to crap
> engineering in the various components in pararell tracking arms or worn
> bearing in the pivoted arms. Brian

I'm surprised such a thing (a ghetto blaster that plays LPs) existed
after compact cassettes were common (and mostly good quality, especially
the ones you recorded yourself).

--
Max Demian

>On 16/08/2023 11:32, Brian Gaff wrote:
[]
>> main one, Then I think it was TRY, which was a little psu to make the p-5v
>> from the +5 coming out of the regulator, If this failed badly it could take
>> a ram chip with it, and failed to power add ons like vtx 500 modems and the
[]
Reminds me of two power supply decisions:

1. The Oric (and I presume the Oric Atmos), mostly TTL logic so needed a
+5 supply: the power supply they provided used a -5 regulator. I don't
know why: I can only guess that the common 7905 regulator was cheaper
than the 7805. It was fine with the basic computer, but got interesting
when you added peripherals, such as the disc drive, which had a beefier
supply, which also powered the computer. (Having said that, I don't
remember it ever actually going wrong.)

2. (Earlier - same company, Tangerine [the Oric said Tangerine on the
PCB].) When the Tangerine came out, the ASTEC modulator (most home
computers then used a domestic TV as monitor, and had to provide RF as
few TVs had baseband input) - little tin box, common on virtually all
home computers! - was initially only available with a 6V rail. Since the
rest of the computer ran on 5V, it would have been tedious to provide a
separate supply just for that - so they designed in a little circuit,
using IIRR the dot clock of 6 MHz (I think the computer ran on 0.75 MHz)
and a teeny inductor: my first experience of a switch-mode supply (only
about 3 components). (FWIW, it seemed to work fine.) [ASTEC subsequently
made the boxes to run on 5V.]

That reminds me - I did hear that one of the other machines around then
(Nascom was it?) was laid out with computer layout software - but that
knew nothing of RF, and they included the modulator in what they gave
it; of course, it never worked, and they had to bodge in an ASTEC tin
box anyway. Whether this is true or not I've no idea.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

.... a series about a grumpy old man who lives in a phone box is unlikely to
have been commissioned these days. 798 episodes later ...

On Sun 03/09/2023 14:20, J. P. Gilliver wrote:
>> On 16/08/2023 11:32, Brian Gaff wrote:
> []
>>> main one, Then I think it was TRY, which was a little psu to make the
>>> p-5v
>>> from the +5  coming out of the regulator, If this failed badly it
>>> could take
>>> a ram chip with it, and failed to power add ons like vtx 500 modems
>>> and the
> []
> Reminds me of two power supply decisions:
>
> 1. The Oric (and I presume the Oric Atmos), mostly TTL logic so needed a
> +5 supply: the power supply they provided used a -5 regulator. I don't
> know why: I can only guess that the common 7905 regulator was cheaper
> than the 7805. It was fine with the basic computer, but got interesting
> when you added peripherals, such as the disc drive, which had a beefier
> supply, which also powered the computer. (Having said that, I don't
> remember it ever actually going wrong.)
>
> 2. (Earlier - same company, Tangerine [the Oric said Tangerine on the
> PCB].) When the Tangerine came out, the ASTEC modulator (most home
> computers then used a domestic TV as monitor, and had to provide RF as
> few TVs had baseband input) - little tin box, common on virtually all
> home computers! - was initially only available with a 6V rail. Since the
> rest of the computer ran on 5V, it would have been tedious to provide a
> separate supply just for that - so they designed in a little circuit,
> using IIRR the dot clock of 6 MHz (I think the computer ran on 0.75 MHz)
> and a teeny inductor: my first experience of a switch-mode supply (only
> about 3 components). (FWIW, it seemed to work fine.) [ASTEC subsequently
> made the boxes to run on 5V.]
>
> That reminds me - I did hear that one of the other machines around then
> (Nascom was it?) was laid out with computer layout software - but that
> knew nothing of RF, and they included the modulator in what they gave
> it; of course, it never worked, and they had to bodge in an ASTEC tin
> box anyway. Whether this is true or not I've no idea.

-5V was probably to work RS232 with +5V from elsewhere.

In message <ud273d$v8rq$1@dont-email.me> at Sun, 3 Sep 2023 16:01:01,
Woody <harrogate3@ntlworld.com> writes
>On Sun 03/09/2023 14:20, J. P. Gilliver wrote:
[]
>> 1. The Oric (and I presume the Oric Atmos), mostly TTL logic so
>>needed a +5 supply: the power supply they provided used a -5
>>regulator. I don't know why: I can only guess that the common 7905
>>regulator was cheaper than the 7805. It was fine with the basic
>>computer, but got interesting when you added peripherals, such as the
>>disc drive, which had a beefier supply, which also powered the
>>computer. (Having said that, I don't remember it ever actually going wrong.)
[]
>-5V was probably to work RS232 with +5V from elsewhere.

No, I can't remember whether it even _had_ a serial port - I think not.
What I mean is, it had a 7905 (-5V) regulator to supply the main +5V for
the computer. So ground wasn't, as it were.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

If you carry on hating, you're the one who's damaged.
- Sir Harold Atcherley, sent to the Burma/Siam railway in April 1943

J. P. Gilliver <G6JPG@255soft.uk> wrote:

[...]
> I don't think I've ever heard of the zigzag type of multiplier ever
> being used with thermionic rectifiers (you'd need several such,
> obviously), so I think they only became practical with solid-state
> rectifiers.

https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
ical-Review/40s/Philips-Technical-Review-1949.pdf

Page 123:
"Heating the Filaments of Valves in a Cascade Generator by Means of High
Frequency Current" by Tj. Douma & H.P.J. Brekoo.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <1qgojd0.8wdt9v1qiaif4N%liz@poppyrecords.invalid.invalid> at
Thu, 7 Sep 2023 08:56:22, Liz Tuddenham
<liz@poppyrecords.invalid.invalid> writes
>J. P. Gilliver <G6JPG@255soft.uk> wrote:
>
>[...]
>> I don't think I've ever heard of the zigzag type of multiplier ever
>> being used with thermionic rectifiers (you'd need several such,
>> obviously), so I think they only became practical with solid-state
>> rectifiers.
>
>https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
>ical-Review/40s/Philips-Technical-Review-1949.pdf
>
>Page 123:
>"Heating the Filaments of Valves in a Cascade Generator by Means of High
>Frequency Current" by Tj. Douma & H.P.J. Brekoo.
>
>
Most ingenious! I think only for professional equipment, though. Clever
to pass the h. f. up the same lines as the (presumably mains) frequency
being used to generate the EHT.

Of course, in a TV set the signal being rectified is moderately h. f.
(compared to mains, anyway). The only case I've come across in a TV set
was a little (11"?) dual-standard portable, which had a little D (2V)
valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
(IIRR) turns of thicker wire wound round the LOPT core to drive its
heater. (Very simple valve - about the shape and size of a gherkin; just
a single pin sticking out the top for the EHT, I can't remember what it
had at the base.) I replaced it with a solid-state stick - can't
remember why, I think it became intermittent. (The stick gave a brighter
slightly smaller picture - I presume higher voltage, so brighter and
deflected less.) I never worked on (the EHT part of, anyway) any bigger
set, so I don't know if any used multiple valve rectifiers in a
multiplier arrangement; I'd have thought that would be a complex and
error-prone thing to design and keep going in a domestic setting
(compared to doing it with solid-state stick rectifiers when those
became available), but I could be wrong.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Another lively meeting of thr 1922 Committee - the secret gathering of BBC
presenters that gets its name from the fact that no one is sober after
twenty-past seven. - Eddie Mair, RT 16-22 April 2011

J. P. Gilliver <G6JPG@255soft.uk> wrote:

>... The only case I've come across in a TV set
> was a little (11"?) dual-standard portable, which had a little D (2V)
> valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
> (IIRR) turns of thicker wire wound round the LOPT core to drive its
> heater.

They were usually EY51 (6.3v heater). They had no base, so the
heater/cathode wires were soldered to the terminals of the LOPT with big
rounded solder blobs to reduce corona discharge. Possibly a DY51, with
lower heater requirements, would have been used in a portable set.

EY51s were also used in the tripler of the Philips projection
television, immersed in oil and sealed in a metal can. This is
described in a series of articles beginning on p.69 of:
https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
ical-Review/40s/Philips-Technical-Review-1949.pdf

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

Liz Tuddenham <liz@poppyrecords.invalid.invalid> wrote:

Corrected URL:

>...This is
> described in a series of articles beginning on p.69 of:

> https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
> ical-Review/40s/Philips-Technical-Review-1948.pdf

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <1qgot8k.yqnxuj1vn138mN%liz@poppyrecords.invalid.invalid> at
Thu, 7 Sep 2023 12:37:09, Liz Tuddenham
<liz@poppyrecords.invalid.invalid> writes
>J. P. Gilliver <G6JPG@255soft.uk> wrote:
>
>>... The only case I've come across in a TV set
>> was a little (11"?) dual-standard portable, which had a little D (2V)
>> valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
>> (IIRR) turns of thicker wire wound round the LOPT core to drive its
>> heater.
>
>They were usually EY51 (6.3v heater). They had no base, so the
>heater/cathode wires were soldered to the terminals of the LOPT with big
>rounded solder blobs to reduce corona discharge. Possibly a DY51, with
>lower heater requirements, would have been used in a portable set.
>
Could have been DY51. From what I remember, it had a plastic base
(possibly just that took wires - I don't think I ever removed the valve
from it to see) and was just floating inside the LOPT can (prevented
from moving by the stiffness of the EHT lead[s]), with the plastic base
having some thickish wires coming out of it that went a couple of times
round the LOPT core - no soldering.
>
>EY51s were also used in the tripler of the Philips projection
>television, immersed in oil and sealed in a metal can. This is
>described in a series of articles beginning on p.69 of:
>https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
>ical-Review/40s/Philips-Technical-Review-1949.pdf
>
>
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

WANTED, Dead AND Alive: Schrodinger's Cat

In article <FgN+IjZpKZ+kFwIR@255soft.uk>, J. P. Gilliver
<G6JPG@255soft.uk> scribeth thus
>In message <1qgojd0.8wdt9v1qiaif4N%liz@poppyrecords.invalid.invalid> at
>Thu, 7 Sep 2023 08:56:22, Liz Tuddenham
><liz@poppyrecords.invalid.invalid> writes
>>J. P. Gilliver <G6JPG@255soft.uk> wrote:
>>
>>[...]
>>> I don't think I've ever heard of the zigzag type of multiplier ever
>>> being used with thermionic rectifiers (you'd need several such,
>>> obviously), so I think they only became practical with solid-state
>>> rectifiers.
>>
>>https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
>>ical-Review/40s/Philips-Technical-Review-1949.pdf
>>
>>Page 123:
>>"Heating the Filaments of Valves in a Cascade Generator by Means of High
>>Frequency Current" by Tj. Douma & H.P.J. Brekoo.
>>
>>
>Most ingenious! I think only for professional equipment, though. Clever
>to pass the h. f. up the same lines as the (presumably mains) frequency
>being used to generate the EHT.
>
>Of course, in a TV set the signal being rectified is moderately h. f.
>(compared to mains, anyway). The only case I've come across in a TV set
>was a little (11"?) dual-standard portable, which had a little D (2V)
>valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
>(IIRR) turns of thicker wire wound round the LOPT core to drive its
>heater. (Very simple valve - about the shape and size of a gherkin; just
>a single pin sticking out the top for the EHT, I can't remember what it
>had at the base.) I replaced it with a solid-state stick - can't
>remember why, I think it became intermittent. (The stick gave a brighter
>slightly smaller picture - I presume higher voltage, so brighter and
>deflected less.) I never worked on (the EHT part of, anyway) any bigger
>set, so I don't know if any used multiple valve rectifiers in a
>multiplier arrangement; I'd have thought that would be a complex and
>error-prone thing to design and keep going in a domestic setting
>(compared to doing it with solid-state stick rectifiers when those
>became available), but I could be wrong.

Useful source the Valve museum. They have got the EY and DY wire ended
valves in there and I do remember Selenium rectifiers both mains voltage
and EHT could tell when they failed they simply stunk the house out!..

Http://www.r-type.org/exhib/aaa1233.htm

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

tony sayer <tony@bancom.co.uk> wrote:

> In article <FgN+IjZpKZ+kFwIR@255soft.uk>, J. P. Gilliver
> <G6JPG@255soft.uk> scribeth thus
> >In message <1qgojd0.8wdt9v1qiaif4N%liz@poppyrecords.invalid.invalid> at
> >Thu, 7 Sep 2023 08:56:22, Liz Tuddenham
> ><liz@poppyrecords.invalid.invalid> writes
> >>J. P. Gilliver <G6JPG@255soft.uk> wrote:
> >>
> >>[...]
> >>> I don't think I've ever heard of the zigzag type of multiplier ever
> >>> being used with thermionic rectifiers (you'd need several such,
> >>> obviously), so I think they only became practical with solid-state
> >>> rectifiers.
> >>
> >>https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
> >>ical-Review/40s/Philips-Technical-Review-1949.pdf
> >>
> >>Page 123:
> >>"Heating the Filaments of Valves in a Cascade Generator by Means of High
> >>Frequency Current" by Tj. Douma & H.P.J. Brekoo.
> >>
> >>
> >Most ingenious! I think only for professional equipment, though. Clever
> >to pass the h. f. up the same lines as the (presumably mains) frequency
> >being used to generate the EHT.
> >
> >Of course, in a TV set the signal being rectified is moderately h. f.
> >(compared to mains, anyway). The only case I've come across in a TV set
> >was a little (11"?) dual-standard portable, which had a little D (2V)
> >valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
> >(IIRR) turns of thicker wire wound round the LOPT core to drive its
> >heater. (Very simple valve - about the shape and size of a gherkin; just
> >a single pin sticking out the top for the EHT, I can't remember what it
> >had at the base.) I replaced it with a solid-state stick - can't
> >remember why, I think it became intermittent. (The stick gave a brighter
> >slightly smaller picture - I presume higher voltage, so brighter and
> >deflected less.) I never worked on (the EHT part of, anyway) any bigger
> >set, so I don't know if any used multiple valve rectifiers in a
> >multiplier arrangement; I'd have thought that would be a complex and
> >error-prone thing to design and keep going in a domestic setting
> >(compared to doing it with solid-state stick rectifiers when those
> >became available), but I could be wrong.
>
>
> Useful source the Valve museum. They have got the EY and DY wire ended
> valves in there and I do remember Selenium rectifiers both mains voltage
> and EHT could tell when they failed they simply stunk the house out!..

There was a story circulating in the late 1960s of a service engineer
who turned up to repair a television set. As the housewife opened the
door he took one sniff, walked back to the van and returned with a
selenium rectifier. He had diagnosed the problem without even entering
the house.

If you want to be reminded of the smell, try sniffing an anti-dandruff
shampoo which contains selenium sulphide.

--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

In message <5sr91xAuKy+kFw++@bancom.co.uk> at Fri, 8 Sep 2023 14:33:34,
tony sayer <tony@bancom.co.uk> writes
[]
>Useful source the Valve museum. They have got the EY and DY wire ended
>valves in there and I do remember Selenium rectifiers both mains voltage
>and EHT could tell when they failed they simply stunk the house out!..
>
>
>
>Http://www.r-type.org/exhib/aaa1233.htm
>
>
That looks like the one I had, though I think the base was in a white
plastic holder with the heater turns moulded into it. Interesting to see
its absolute maximum was only 15 kV.
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

It's quickly getting to a place where privacy will be cause for suspicion.
- Mayayana in alt.windows7.general, 2018-11-6.

In article <1qgr20m.xvm0yctbcnekN%liz@poppyrecords.invalid.invalid>, Liz
Tuddenham <liz@poppyrecords.invalid.invalid> scribeth thus
>tony sayer <tony@bancom.co.uk> wrote:
>
>> In article <FgN+IjZpKZ+kFwIR@255soft.uk>, J. P. Gilliver
>> <G6JPG@255soft.uk> scribeth thus
>> >In message <1qgojd0.8wdt9v1qiaif4N%liz@poppyrecords.invalid.invalid> at
>> >Thu, 7 Sep 2023 08:56:22, Liz Tuddenham
>> ><liz@poppyrecords.invalid.invalid> writes
>> >>J. P. Gilliver <G6JPG@255soft.uk> wrote:
>> >>
>> >>[...]
>> >>> I don't think I've ever heard of the zigzag type of multiplier ever
>> >>> being used with thermionic rectifiers (you'd need several such,
>> >>> obviously), so I think they only became practical with solid-state
>> >>> rectifiers.
>> >>
>> >>https://worldradiohistory.com/Archive-Company-Publications/Philips-Techn
>> >>ical-Review/40s/Philips-Technical-Review-1949.pdf
>> >>
>> >>Page 123:
>> >>"Heating the Filaments of Valves in a Cascade Generator by Means of High
>> >>Frequency Current" by Tj. Douma & H.P.J. Brekoo.
>> >>
>> >>
>> >Most ingenious! I think only for professional equipment, though. Clever
>> >to pass the h. f. up the same lines as the (presumably mains) frequency
>> >being used to generate the EHT.
>> >
>> >Of course, in a TV set the signal being rectified is moderately h. f.
>> >(compared to mains, anyway). The only case I've come across in a TV set
>> >was a little (11"?) dual-standard portable, which had a little D (2V)
>> >valve hidden inside the LOPT casing (DY91 rings a bell?); it had two
>> >(IIRR) turns of thicker wire wound round the LOPT core to drive its
>> >heater. (Very simple valve - about the shape and size of a gherkin; just
>> >a single pin sticking out the top for the EHT, I can't remember what it
>> >had at the base.) I replaced it with a solid-state stick - can't
>> >remember why, I think it became intermittent. (The stick gave a brighter
>> >slightly smaller picture - I presume higher voltage, so brighter and
>> >deflected less.) I never worked on (the EHT part of, anyway) any bigger
>> >set, so I don't know if any used multiple valve rectifiers in a
>> >multiplier arrangement; I'd have thought that would be a complex and
>> >error-prone thing to design and keep going in a domestic setting
>> >(compared to doing it with solid-state stick rectifiers when those
>> >became available), but I could be wrong.
>>
>>
>> Useful source the Valve museum. They have got the EY and DY wire ended
>> valves in there and I do remember Selenium rectifiers both mains voltage
>> and EHT could tell when they failed they simply stunk the house out!..
>
>
>There was a story circulating in the late 1960s of a service engineer
>who turned up to repair a television set. As the housewife opened the
>door he took one sniff, walked back to the van and returned with a
>selenium rectifier. He had diagnosed the problem without even entering
>the house.
>
>If you want to be reminded of the smell, try sniffing an anti-dandruff
>shampoo which contains selenium sulphide.
>
>
Yes it did stink how ever we were given a stock of silicon wire ended
diodes these could be wired across the old unit one end left
disconnected..

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.