DX TV

[Brian Gaff]

In them old days when we were all analogue and all that, and I could see, I
used to enjoy getting distant tv transmitters. I think the first time an old
TV fitted with a vhf tuner that worked even in 625 mode I saw Sveridge's
Radio test card with that nice young lady on it was amazing. Of course back
then you could pick up the itv 405 regions on a modest rotatable aerial.
Now we are all digital, no longer use vhf for TV and multiplex loads of
channels into one on uhf, I have never found much to look for. I guess if
you lived on the downs and had a clear path to parts of Europe you might get
something, but co channel is now very bad and digital is now you see it now
you don't, Even fm radio is now so jammed with legal and illegal stations as
to be impossible to get much.
We never knew back then that we were living through an all too short golden
period of TV dx.
Brian

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[williamwright]

On 22/07/2022 09:14, Brian Gaff wrote:
> We never knew back then that we were living through an all too short golden
> period of TV dx.

Indeed.

Bill

[Ian Jackson]

In message <jk00q9...@mid.individual.net>, williamwright
<wrights...@f2s.com> writes

I think that the period from around 1950 to 1980 was a golden age for
all sorts of electronic hobbies. Loads of war surplus gear and a vast
quantity of components that you could work with. And you could also
really understand how things worked. These days, you can't get the bits
any more, or it's all done for you (or at least just modules that you
can connect together), or you simply can't do it any more.
--
Ian

[Jeff Layman]

+1

As a teenager I was often browsing around the electronic surplus shops
in Tottenham Court Road and Lisle Street in London. I guess other big
cities had shops of that sort too.

--

Jeff

[Tweed]

That’s just nostalgia. There’s now a semi infinite range of electronic bits
and bobs you can get from China via the likes of eBay. As to bemoaning
modules, presumably you’d also dislike ICs because they hide all those
hundreds of thousands of transistors. You can buy a Raspberry Pi Pico for
£6 and get right into the nuts and bolts of bare metal programming, drive
the i/o lines with I2C, SPI etc and hook up all sorts of external
peripheral chips. CAD packages have never been more accessible, with very
competent suites being free. PCBs can be manufactured for next to nothing
and returned within a week or two. You can buy a USB software radio stick
for peanuts and get into software defined radio.

[MB]

On 23/07/2022 08:40, Jeff Layman wrote:
> As a teenager I was often browsing around the electronic surplus shops
> in Tottenham Court Road and Lisle Street in London. I guess other big
> cities had shops of that sort too.

That's your excuse for being in Lisle Street :-)

[Jim Lesurf]

In article <tbdm9l$304mo$1...@dont-email.me>, Brian Gaff

<brian...@gmail.com> wrote:
> Even fm radio is now so jammed with legal and illegal stations as to be
> impossible to get much.

FM/VHF in London was jammed decades ago when I lived there - plus all kinds
of interference!. However where I live now the band is still in a decent
state. So it matters a lot where you are.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

[charles]

In article <tbgamv$3ogo2$1...@dont-email.me>,

what other reason could there be?

--
from KT24 in Surrey, England - sent from my RISC OS 4té
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

[The Other John]

On Sat, 23 Jul 2022 09:47:15 +0100, charles wrote:

> what other reason could there be?

Was that tongue in cheek? If not, it was reputed to be an area of loose
morals and even looser underwear! I never noticed these things as I was
more interested in the junk.

--
TOJ

[MB]

On 23/07/2022 10:35, The Other John wrote:
> Was that tongue in cheek? If not, it was reputed to be an area of loose
> morals and even looser underwear! I never noticed these things as I was
> more interested in the junk.

It was after all in Soho I seem to remember.

[The Other John]

On Sat, 23 Jul 2022 10:45:50 +0100, MB wrote:

> It was after all in Soho I seem to remember.

I thought Soho ended at Shaftesbury Avenue and Lisle Street is south of
that.

--
TOJ

[Brian Gaff]

Maybe it does, but the problem for me now is that there is a transmitter for
the local independent station on top of the Tolworth Tower block, so this
shoots intermediation spurii all over the bands. Its less than a mile away.
Likewise, Medium wave has one of the God stations for Premier very close
to here, completely dispensing the band.

Brian

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"Jim Lesurf" <no...@audiomisc.co.uk> wrote in message
news:5a0beb1...@audiomisc.co.uk...

[Brian Gaff]

That is a whole other subject of course. The advent of surface mount
components put all the joy out of electronics. OK so I lost my sight just
around those times, but the shock of taking the top off a cd player and
finding a tiny pcb and a little switch mode psu inside and no adjustments
for the mechanical bits, was just too much.

Brian

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"Ian Jackson" <ianREMOVET...@g3ohx.co.uk> wrote in message
news:cw50EYHN...@brattleho.plus.com...

[Brian Gaff]

Yes but did they also have all those ladies propositioning you as well an a
lot of Chinese!

Yup, well, I guess front 1966 to mid 80s I was old enough to go to such
shops for electronic parts, but because my father worked for a TV company we
would get all sorts of things to play with, so modifying TVs to get 819
lines and having to have a completely separate if and tuner for the sound
was quite achievable, even intercarrier sound offsets could be done by a
second IF with a tunable oscillator to pretend to be the vision carrier for
the other IF. I think the weirdest experiences toward the end of the 50s
was getting weak audio signals at the low end of band 1 from Australia, as
they used like we did, AM sound down at around 41.5 ish MHz. Had to be a
good sunspot year though and you would have no chance if they did it now due
to the noise generated by our modern gear.

Brian

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"Jeff Layman" <Je...@invalid.invalid> wrote in message
news:tbg8l1$3o1ha$1...@dont-email.me...

[Brian Gaff]

With respect that is hardly the same is it? The low level understanding of
how things worked was the thing back then. Now for all the items you
mention, you are relying on other peoples designs and merely putting them
together. If for example they decide to put a monitoring chip into your Pi
and then monitor what you are doing you would have no idea at all.

Brian

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"Tweed" <usenet...@gmail.com> wrote in message
news:tbgafi$3ofh9$1...@dont-email.me...

[Brian Gaff]

I already cracked that joke in this thread and previously, don't be silly we
liked to rummage in drawers but only looking for rare components.

Brian

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"MB" <M...@nospam.net> wrote in message news:tbgamv$3ogo2$1...@dont-email.me...

[Brian Gaff]

Gw Smith, Laskys, yes the original, and in other streets Proops of course
for all their novelties.
We used to have in Kingston a shop called Southern Surplus, and the floor
was rotting but it was piled high with gear from the forces, redundant stock
and returns etc, much fun to be had.

Brian

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"charles" <cha...@candehope.me.uk> wrote in message
news:5a0c6c57...@candehope.me.uk...

[Brian Gaff]

I managed to get an old Antex insulator there, and modified it for phased
crossed dipoles with a phasing harness and 50 ohm stub, and then cut some
ally tubing got from London Metal Warehouses when you could just walk in
measure and pay for it.

Brian

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"The Other John" <nom...@here.org> wrote in message
news:tbgfcn$3pkbc$1...@dont-email.me...

[Brian Gaff]

Just around the corner of course was Denmark Street where Dick James Music
used to have his office where all the aspiring young stars sent their
acetates. Loads were found when they cleared it out some years ago.
Cilla, the Beatles, seems such a short time ago, and the quality was crap,
now demos are either sent via email or sold off as very polished tracks
directly by the artists.

Brian

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"MB" <M...@nospam.net> wrote in message news:tbgg0d$3pr11$1...@dont-email.me...

[Brian Gaff]

That is probably the modern gentrification definition.
There war so many jokes at the time though. Brian

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"The Other John" <nom...@here.org> wrote in message

news:tbggqt$3q17b$1...@dont-email.me...

[Jeff Layman]

Remember that at the time (early 60s) transistor devices were in their
infancy, so may things were still made with valves. There was still a
lot of ex-WW2 electronic equipment around, and much of it was available
for very little money. It was fun to try to get old equipment working,
but I failed miserably with a USAF VHF radio - a BC-624 (this would have
helped at the time:
<http://www.radiomanual.info/schemi/Surplus_NATO/SCR-522A_SCR-542A_user_AN16-40SCR522-2_1944.pdf>.
But even that doesn't have the circuit diagram.). I also tried to get an
old Cossor 3339 oscilloscope working, but could not get it to scan.
Today, you'd get a module, often with unmarked or anonymised ICs, or
buried under a blob of epoxy resin. What fun is there buying from eBay,
other than you not knowing exactly what you might be getting from a
Chinglish description?

In the Electronics Surplus shops you could look at and pick up all sorts
of equipment that you had no idea of what it was or what it did, and
often the shop owner didn't either. It was a journey of discovery, and
/you/ did the thinking, not someone else doing it for you with a
ready-made kit.

--

Jeff

[Tweed]

There a lot of room for thinking, there’s endless small developer kits with
microcontrollers and even FPGAs if you really want to exercise the brain
cells. The world has moved on.

[Sn!pe]

"French Lessons, fourth floor; ring and walk up".

--
^Ï^ My pet rock Gordon just is.

~ Slava Ukraini ~

[Java Jive]

On 23/07/2022 12:45, Brian Gaff wrote:
>
> Just around the corner of course was Denmark Street

Which IIRC had a musical instrument shop where I got a zither repaired.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

[Roderick Stewart]

On Sat, 23 Jul 2022 12:51:51 -0000 (UTC), Tweed
<usenet...@gmail.com> wrote:

>> But even that doesn't have the circuit diagram.). I also tried to get an
>> old Cossor 3339 oscilloscope working, but could not get it to scan.
>> Today, you'd get a module, often with unmarked or anonymised ICs, or
>> buried under a blob of epoxy resin. What fun is there buying from eBay,
>> other than you not knowing exactly what you might be getting from a
>> Chinglish description?
>>
>> In the Electronics Surplus shops you could look at and pick up all sorts
>> of equipment that you had no idea of what it was or what it did, and
>> often the shop owner didn't either. It was a journey of discovery, and
>> /you/ did the thinking, not someone else doing it for you with a
>> ready-made kit.
>>
>
>There a lot of room for thinking, there’s endless small developer kits with
>microcontrollers and even FPGAs if you really want to exercise the brain
>cells. The world has moved on.

Not quite all of it. Somebody must be designing those blob circuits,
so there's probably about a dozen people in the entire world somewhere
who still know how stuff actually works. Goodness knows how the next
generation of youngsters are going to learn it though.

Rod.

[Jim Lesurf]

In article <tbg8l1$3o1ha$1...@dont-email.me>, Jeff Layman

<Je...@invalid.invalid> wrote:

> As a teenager I was often browsing around the electronic surplus shops
> in Tottenham Court Road and Lisle Street in London. I guess other big
> cities had shops of that sort too.

We had a local trader wih three shops. One mainly sold radios and hi-fi of
the period. The other two sold electronics of all kinds. Usually had a
table outside with carboard boxes/trays of assorted loose components.
Valves to resistors, etc.

[Tweed]

It is reputed that no one person knows in fine detail how a modern Intel
microprocessor works. However, there’s lots of fields where no one person
knows how something works in detail.

The problem with getting old is that you know how difficult everything is,
so it is very hard to get motivated to learn new stuff. Happily the
youngsters aren’t weighed down with this knowledge and thus take easily to
new things.

The real issue is not the inability of the young to learn engineering, but
rather the pathetic pay rates for electronic engineers and the poor long
term career prospects if you want to remain in the technical side rather
than migrating to flying a desk in management. Dyson was attempting to
justify his outsourcing to the Far East on the grounds he couldn’t recruit
decent engineers in the UK. Having looked at the salaries he was offering
in their job adverts it was hardly surprising he couldn’t recruit.

[Ian Jackson]

In message <tbj1nq$gm4k$1...@dont-email.me>, Tweed <usenet...@gmail.com>
writes

>
>It is reputed that no one person knows in fine detail how a modern Intel
>microprocessor works. However, there’s lots of fields where no one person
>knows how something works in detail.

I recall having to contact my works parent company about problems I
having getting one of their products to work. The reply was "The guy who
designed it is dead, and the guy who might possibly have some idea has
left town".
>

>

--
Ian

[Jeff Layman]

I know exactly what you mean!

The pharmaceutical company I worked for had a foamed product which was
made in the USA by one guy. Before he retired, they had him write a
detailed description of the process for his replacement to follow. The
new guy tried several times, but the product did not foam correctly.
They got the old guy back and asked him to make a batch while they
watched. Towards the end of the process (where it kept going wrong for
the new guy), with the old guy peering into the reaction vessel, he
"pressed the button" and it worked perfectly. They asked the old guy how
he knew when to press the button to enable the process to work. His
answer? "It looked right".

There's no substitute for experience!

--

Jeff

[Roderick Stewart]

On Sun, 24 Jul 2022 09:00:42 -0000 (UTC), Tweed
<usenet...@gmail.com> wrote:

>The problem with getting old is that you know how difficult everything is,
>so it is very hard to get motivated to learn new stuff. Happily the
>youngsters aren’t weighed down with this knowledge and thus take easily to
>new things.

The trouble is that although most modern electronics is very
complicated it's still based on fundamental principles. Much of my own
knowledge of these pronciples was gained by practical experience, but
the knowledge that today's kids will be able to gain by practical
experience will mostly be from things that are already built, so how
will they cope when it becomes necessary to design and build new
things from scratch?

Rod.

[Tweed]

Has the maker movement that involves the Arduino and Raspberry Pi passed
you by?

[tony sayer]

In article <tbglhq$3r8f9$1...@dont-email.me>, Brian Gaff
<brian...@gmail.com> scribeth thus

>Maybe it does, but the problem for me now is that there is a transmitter for
>the local independent station on top of the Tolworth Tower block, so this
>shoots intermediation spurii all over the bands. Its less than a mile away.
> Likewise, Medium wave has one of the God stations for Premier very close
>to here, completely dispensing the band.
> Brian
>

Well if you think that is the case then write and complain to Ofcom!

If your sure their TX system is at fault;!...
--
Tony Sayer


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

Give him a keyboard, and he will reveal himself.

[tony sayer]

In article <tbg8l1$3o1ha$1...@dont-email.me>, Jeff Layman

<Je...@invalid.invalid> scribeth thus

>On 22/07/2022 21:33, Ian Jackson wrote:
>> In message <jk00q9...@mid.individual.net>, williamwright
>> <wrights...@f2s.com> writes
>>> On 22/07/2022 09:14, Brian Gaff wrote:
>>>> We never knew back then that we were living through an all too short
>golden
>>>> period of TV dx.
>>>
>>> Indeed.
>>>
>> I think that the period from around 1950 to 1980 was a golden age for
>> all sorts of electronic hobbies. Loads of war surplus gear and a vast
>> quantity of components that you could work with. And you could also
>> really understand how things worked. These days, you can't get the bits
>> any more, or it's all done for you (or at least just modules that you
>> can connect together), or you simply can't do it any more.
>
>+1
>

>As a teenager I was often browsing around the electronic surplus shops
>in Tottenham Court Road and Lisle Street in London. I guess other big
>cities had shops of that sort too.
>

Even here in Cambridge we had H. Gee in Mill road who sold no end of
stuff, used to spend most all of my pocket money there in the Sixties!

Few years ago it burnt down, there were thousands of cassette player
belts in there, pitiful to see it all go up and its still in its burnt
state!..


https://goo.gl/maps/NLAN4KHUKqDM3Hz26

[tony sayer]

In article <tbgmn8$3rhq4$1...@dont-email.me>, Brian Gaff
<brian...@gmail.com> scribeth thus

>Gw Smith, Laskys, yes the original, and in other streets Proops of course
>for all their novelties.
> We used to have in Kingston a shop called Southern Surplus, and the floor
>was rotting but it was piled high with gear from the forces, redundant stock
>and returns etc, much fun to be had.
> Brian
>

Up in Lincolnshire Birketts of the street is still there after all those
years!

https://goo.gl/maps/g8Vvdrh8qGdjMuWh8



Is it was it Johns radio in Leeds?, still around?...

[Jeff Layman]

On 24/07/2022 21:40, tony sayer wrote:
> In article <tbgmn8$3rhq4$1...@dont-email.me>, Brian Gaff
> <brian...@gmail.com> scribeth thus
>> Gw Smith, Laskys, yes the original, and in other streets Proops of course
>> for all their novelties.
>> We used to have in Kingston a shop called Southern Surplus, and the floor
>> was rotting but it was piled high with gear from the forces, redundant stock
>> and returns etc, much fun to be had.
>> Brian
>>
>
>
>
> Up in Lincolnshire Birketts of the street is still there after all those
> years!
>
> https://goo.gl/maps/g8Vvdrh8qGdjMuWh8

That's 3 years old.

John Birkett died three months ago. Anyone know if the shop is still open?

--

Jeff

[Roderick Stewart]

On Sun, 24 Jul 2022 13:39:24 -0000 (UTC), Tweed

<usenet...@gmail.com> wrote:

>Roderick Stewart <rj...@escapetime.myzen.co.uk> wrote:
>> On Sun, 24 Jul 2022 09:00:42 -0000 (UTC), Tweed
>> <usenet...@gmail.com> wrote:
>>
>>> The problem with getting old is that you know how difficult everything is,
>>> so it is very hard to get motivated to learn new stuff. Happily the

>>> youngsters aren?t weighed down with this knowledge and thus take easily to

>>> new things.
>>
>> The trouble is that although most modern electronics is very
>> complicated it's still based on fundamental principles. Much of my own
>> knowledge of these pronciples was gained by practical experience, but
>> the knowledge that today's kids will be able to gain by practical
>> experience will mostly be from things that are already built, so how
>> will they cope when it becomes necessary to design and build new
>> things from scratch?
>>
>> Rod.
>>
>
>Has the maker movement that involves the Arduino and Raspberry Pi passed
>you by?

Arduinos and the like are full of ready made electronics. I'm sure
they can teach a lot about digital logic, but possibly not so much
about the behaviour of electrical signals in cables or through the
air. You just plug one ready made circuit module to another using
ready made cables with the plugs already attached, and assume that the
signals will just arrive where they should, unharmed. No need to worry
about impedances or balancing or matching. No need to calculate things
like component values or power dissipations. Just rely on the makers'
specifications and assume everything will work.

Rod.

[Tweed]

But that’s the beauty of things digital. You are worrying about where kids
start. They aren’t going to start by worrying about the things you list,
and probably never have. Those that get their interest piqued might go on
to study engineering. There you will learn about the darker arts. You are
forgetting all the things you never learnt as a hobbyist with war surplus.
Nothing digital, no programming, no coding for FPGAs etc, no digital signal
processing. Electronics has changed over the years.

[Jim Lesurf]

In article <280qdh1pf6vgvkp82...@4ax.com>, Roderick Stewart

<rj...@escapetime.myzen.co.uk> wrote:

> Not quite all of it. Somebody must be designing those blob circuits, so
> there's probably about a dozen people in the entire world somewhere who
> still know how stuff actually works. Goodness knows how the next
> generation of youngsters are going to learn it though.

IEEE Spectrum magazine has a "DIY" project in each issue. However it almost
always now involves something like a Raspberry-Pi-alike along with some
soldering and use of a computer controlled 'maker'/ 3D 'printer' to produce
mech parts. So the knowledge base and kit required to get started are tab
above what a teenager looking through boxes of 2nd hand valves might have
had.

e.g. recent issue's example was a Knipkov (spelling?) Disc video camera
where the disc was 'printed' to have square holes!

[David Wade]

On 24/07/2022 11:19, Ian Jackson wrote:

> In message <tbj1nq$gm4k$1...@dont-email.me>, Tweed <usenet...@gmail.com>
> writes
>
>
>>
>> It is reputed that no one person knows in fine detail how a modern Intel
>> microprocessor works. However, there’s lots of fields where no one person
>> knows how something works in detail.

How could any one know the fine detail at all levels, and in reality
they no longer need to. Just we we stopped writing commercial programs
in assembler code and now use high level languages for all

[David Wade]

On 24/07/2022 11:19, Ian Jackson wrote:

> In message <tbj1nq$gm4k$1...@dont-email.me>, Tweed <usenet...@gmail.com>
> writes
>
>
>>
>> It is reputed that no one person knows in fine detail how a modern Intel
>> microprocessor works. However, there’s lots of fields where no one person
>> knows how something works in detail.
>

They don't need to. Any complex chip is designed using high level logic
description languages so the functionality is fully documented and can
me learnt and understood by new designers.

[R. Mark Clayton]

On Friday, 22 July 2022 at 09:14:47 UTC+1, Brian Gaff wrote:
> In them old days when we were all analogue and all that, and I could see, I
> used to enjoy getting distant tv transmitters. I think the first time an old
> TV fitted with a vhf tuner that worked even in 625 mode I saw Sveridge's
> Radio test card with that nice young lady on it was amazing. Of course back
> then you could pick up the itv 405 regions on a modest rotatable aerial.
> Now we are all digital, no longer use vhf for TV and multiplex loads of
> channels into one on uhf, I have never found much to look for. I guess if
> you lived on the downs and had a clear path to parts of Europe you might get
> something, but co channel is now very bad and digital is now you see it now
> you don't, Even fm radio is now so jammed with legal and illegal stations as
> to be impossible to get much.

> We never knew back then that we were living through an all too short golden
> period of TV dx.

> Brian
>

Probably true. Certainly FM radio, where the capture effect means that despite a very well positioned dipole (following Bill's advice) I can receive stations on almost every channel, I can't receive anything distant because nearer stations stamp over it.

As for TV, with a steerable dish you can receive tens of thousands of channels from about a quarter of the globe.

[Jim Lesurf]

In article <6GRdf3Li...@bancom.co.uk>, tony sayer
<to...@bancom.co.uk>
wrote:

> Is it was it Johns radio in Leeds?, still around?...

That name rings a bell. IIRC we(1) bought a 100GHz IEP(?) frequency counter
from them second-hand.

(1) = my old research group. mumble decades ago.

[Jim Lesurf]

In article <tbj1nq$gm4k$1...@dont-email.me>, Tweed
<usenet...@gmail.com>
wrote:

> The problem with getting old is that you know how difficult everything
> is, so it is very hard to get motivated to learn new stuff.

My response hase been different. The more I have discovered, the keener I
have become to find out more. 'New stuff' is interesting - more so when you
can appreciate how impressive the way it was discovered is understood.

> Happily the youngsters aren't weighed down with this knowledge and thus
> take easily to new things.

...alas, that can mean 'learning' what they 'like' in the twitter-sense.
Which can often be nothing like genuine learning about 'stuff' that
requires some study and relates to mere reality. As access to reliable and
useful info has grown, so has a flood of dribble and fasionable 'likes'.

[Max Demian]

It's a matter of degree. Enthusiasts never had to make their own valves
or transistors.

--
Max Demian

[R. Mark Clayton]

I made my own diode, from a small lump of galena I found in the Ochils and literally created my own crystal set. Wound the coil too, but the capacitor was bought. It worked, but OTOH a factory made diode was a lot better.

[williamwright]

On 28/07/2022 20:23, R. Mark Clayton wrote:
> I made my own diode, from a small lump of galena I found in the Ochils and literally created my own crystal set. Wound the coil too, but the capacitor was bought. It worked, but OTOH a factory made diode was a lot better.

When my dad was in the RAMC and was in Italy in the war home-made
crystal sets were common. They used blue razor blades as detectors.

Bill

[NY]

"williamwright" <wrights...@f2s.com> wrote in message
news:jkguf6...@mid.individual.net...

> When my dad was in the RAMC and was in Italy in the war home-made crystal
> sets were common. They used blue razor blades as detectors.

What is special about the razor blades being blue? Were there different
types, colour-coded, with the blue ones found to be best as detectors
(diodes)? A quick google doesn't bring up any references to the phrase,
other that showing photos of razors with blue handles and references to
Gillette's "Silver Blue" blades which seem to be a brand name.

[Roderick Stewart]

My first home made radio used a ready made diode, but I still remember
the thrill of realising I'd put such a thing together and it actually
worked, and not only that but I'd made it having seen the design and
description in a book and understood *how* it worked.

I could see from the schematic in the book that apart from an
earphone, the working of which I already knew, the radio proper
consisted of only three components - a coil, a capacitor and a diode -
and the rest was just wire. Seing how simple it was, I thought "Even I
could understand that", which is what inspired me to read the
explanation more carefully and have a go at building one.

Subsequently I messed about with lots of radio circuits, often winding
my own coils with whatever I had, and realised that at a pinch I could
have made my own tuning capacitors too, out of baking foil and paper
perhaps, and possibly a diode from a lump of coal or a couple of rusty
nails, so I could have made the whole thing from very basic components
and understood what every one of them did.

The first integrated circuits I used contained circuitry for things I
had already had experience of building using discrete components, so
there was no mystery about them; they just saved a bit of work. I had
even made logic circuits out of relays, where you could actually see
what they were doing, so no mystery about those either. I consider
myself lucky to have lived through the particular years of electronic
development that I did, because if I were a youngster today I'm not
sure if any of today's ready made mystery boxes that you just plug in
and expect to work would have inspired me in the same way.

Rod.

[Brian Gaff]

That is true, but its quite an investment and to some extent dependent on
the orientation of a convenient mounting place and a clear view to the
horizon at the equator.
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!

"R. Mark Clayton" <notya...@gmail.com> wrote in message
news:328aab7c-b34b-470b...@googlegroups.com...

[williamwright]

Google "World War II" + "crystal sets"

Bill

[NY]

"williamwright" <wrights...@f2s.com> wrote in message

news:jki3in...@mid.individual.net...

I've found various references to "blue razor blades" but none that explain
the significance of the colour blue. Were razor blades colour-coded in the
past, in a way that used to signify something - like modern green-top
plastic milk bottles are semi-skimmed and blue ones are full-fat (or is it
totally skimmed?). Or green hoses are unleaded petrol and black ones are
diesel? Were there other colours of razor blade at the time which didn't
work as well as detectors?

[williamwright]

On 29/07/2022 16:17, NY wrote:
> I've found various references to "blue razor blades" but none that
> explain the significance of the colour blue. Were razor blades
> colour-coded in the past, in a way that used to signify something - like
> modern green-top plastic milk bottles are semi-skimmed and blue ones are
> full-fat (or is it totally skimmed?). Or green hoses are unleaded petrol
> and black ones are diesel? Were there other colours of razor blade at
> the time which didn't work as well as detectors?

I do not know.

Bill

[David Woolley]

On 29/07/2022 16:17, NY wrote:

> I've found various references to "blue razor blades" but none that
> explain the significance of the colour blue.

I wondered, when I saw this, if they are talking about an interference
blue colour, due to a very thin oxide layer on the steel, rather than an
actual blue paint.

[R. Mark Clayton]

The blades would probably be steel, and blue is the colour steel goes when partly tempered. I doubt that this was significant other than these were what were available.

IIRC I used regular wire, but given the low band gap in lead sulphide as a semiconductor maybe it was something else.

[David Woolley]

On 29/07/2022 19:42, R. Mark Clayton wrote:
> The blades would probably be steel, and blue is the colour steel goes when partly tempered. I doubt that this was significant other than these were what were available.

As suggested in my response, I think this is actually the result of an
oxide layer of the order of the wavelength of light.

>
> IIRC I used regular wire, but given the low band gap in lead sulphide as a semiconductor maybe it was something else.

As I suspected, the razor replaces the crystal, not the contact, see
<https://www.etsy.com/uk/listing/707690484/cornell-ww-ii-foxhole-razor-blade>.
I suspect this is a rather controlled instance of the rusty bolt
effect, as mentioned in the caravan aerial thread.

[tony sayer]

In article <6P-dnStVPqKmE0P_...@brightview.co.uk>, Max
Demian <max_d...@bigfoot.com> scribeth thus

Made a valve once, many years ago and it worked albeit a simple
triode!...

[Max Demian]

On 31/07/2022 21:39, tony sayer wrote:
> In article <6P-dnStVPqKmE0P_...@brightview.co.uk>, Max

>> It's a matter of degree. Enthusiasts never had to make their own valves
>> or transistors.
>>
>
> Made a valve once, many years ago and it worked albeit a simple
> triode!...

How did you evacuate it?

--
Max Demian

[Java Jive]

That's ambiguous, and reminds me of the old joke:

Q: How do you know when you've passed an elephant?
A: You get a burning sensation and tears in yer eyes!

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

[Max Demian]

On 01/08/2022 12:41, Java Jive wrote:
> On 01/08/2022 11:24, Max Demian wrote:
>>
>> On 31/07/2022 21:39, tony sayer wrote:
>>>
>>> Made a valve once, many years ago and it worked albeit a simple
>>> triode!...
>>
>> How did you evacuate it?
>
> That's ambiguous, and reminds me of the old joke:
>
> Q:  How do you know when you've passed an elephant?
> A:  You get a burning sensation and tears in yer eyes!

When they test the fire alarms in the local supermarket the announcement
says, "Do not evacuate the store." I like to add, "...or your bowels."

--
Max Demian

[MB]

On 03/08/2022 12:38, Max Demian wrote:
> When they test the fire alarms in the local supermarket the announcement
> says, "Do not evacuate the store." I like to add, "...or your bowels."

I was watching someone on BBC News (?) talking to their reporter at one
of the football grounds in the last weeks. There was a fire alarm going
off and he said something like "it will only be a test". One of the
people in the studio told him quite firmly that they thought he should
leave NOW.

[Rink]

Op 23-7-2022 om 13:20 schreef Brian Gaff:
> Maybe it does, but the problem for me now is that there is a transmitter for
> the local independent station on top of the Tolworth Tower block, so this
> shoots intermediation spurii all over the bands. Its less than a mile away.
> Likewise, Medium wave has one of the God stations for Premier very close
> to here, completely dispensing the band.
> Brian
>


Which is probably caused in your receiver.
Because of too much signal.

Rink

[tony sayer]

In article <XfKdnXGW6Ph1NHr_...@brightview.co.uk>, Max
Demian <max_d...@bigfoot.com> scribeth thus

A wheeled vacuum pump! It was borrowed from an education establishment!,
it an it did work 'tho not as well as it might have, i didn't have any
"getter" to be fired off for those of you who aren't that old it was a
substance that soaked up the last of the air molecules in the valve when
they say a valve has gone "soft" it means that air has got into it!..

[tony sayer]

In article <tbkd99$r8hn$1...@dont-email.me>, Jeff Layman
<Je...@invalid.invalid> scribeth thus
>On 24/07/2022 21:40, tony sayer wrote:
>> In article <tbgmn8$3rhq4$1...@dont-email.me>, Brian Gaff
>> <brian...@gmail.com> scribeth thus
>>> Gw Smith, Laskys, yes the original, and in other streets Proops of course
>>> for all their novelties.
>>> We used to have in Kingston a shop called Southern Surplus, and the floor
>>> was rotting but it was piled high with gear from the forces, redundant stock
>>> and returns etc, much fun to be had.
>>> Brian
>>>
>>
>>
>>
>> Up in Lincolnshire Birketts of the street is still there after all those
>> years!
>>
>> https://goo.gl/maps/g8Vvdrh8qGdjMuWh8
>
>That's 3 years old.
>
>John Birkett died three months ago. Anyone know if the shop is still open?
>

If i remember I'll phone them up and ask?..

[Java Jive]

On 23/07/2022 12:45, Brian Gaff wrote:
>
> Just around the corner of course was Denmark Street where Dick James Music
> used to have his office where all the aspiring young stars sent their
> acetates. Loads were found when they cleared it out some years ago.
> Cilla, the Beatles, seems such a short time ago, and the quality was crap,
> now demos are either sent via email or sold off as very polished tracks
> directly by the artists.

Oh yeccchhh! Have you seen what's happened to it now?

https://www.theguardian.com/artanddesign/2022/aug/07/outernet-london-now-building-review-denmark-street-tottenham-court-road-redevelopment-soho