The "Two Transistor challenge" - taking things a bit too far?
 

In article , Brian Reay
wrote:

On 18/02/14 20:31, Jerry Stuckle wrote:

There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost
nearly
a week's wages for the average working man, and so it was good
economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of
switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or
"build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to
you?) can
be operated with only 12V on the anode.

No unusual at all.

Not only were a number of valves for the car radio (and possibly other)
markets available, I recall designs which use 'ordinary' valves with
6.3V AC heaters and a voltage doubler and rectifier to provide the "HT".
I recall a one valve design in Radio Constructor, which I build. It was
the 'cover article'. The design called for an Eddystone Box, far too
expensive, so I used a tin box from some short bread.


I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode :)

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At first
glance it sounds crazy - but it made for a very simple and efficient way
to couple the output of the magnetron to the waveguide.


No reason why it shouldn't be done. I can imagine some of the more
"technically challenged" struggling with it but there are always those
who insist that all who have been designing kit for years have got it
wrong.

Indeed it is rather similar to what was done with TV and monitor CRTs,
to interface the screen with people's living rooms at an appropriate
potential!

--

Percy Picacity

The "Two Transistor challenge" - taking things a bit too far?
 

On 2/18/2014 4:29 PM, Percy Picacity wrote:
In article , Brian Reay
wrote:

On 18/02/14 20:31, Jerry Stuckle wrote:

There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost
nearly
a week's wages for the average working man, and so it was good
economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of
switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or
"build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to
you?) can
be operated with only 12V on the anode.

No unusual at all.

Not only were a number of valves for the car radio (and possibly other)
markets available, I recall designs which use 'ordinary' valves with
6.3V AC heaters and a voltage doubler and rectifier to provide the "HT".
I recall a one valve design in Radio Constructor, which I build. It was
the 'cover article'. The design called for an Eddystone Box, far too
expensive, so I used a tin box from some short bread.


I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode :)

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At first
glance it sounds crazy - but it made for a very simple and efficient way
to couple the output of the magnetron to the waveguide.


No reason why it shouldn't be done. I can imagine some of the more
"technically challenged" struggling with it but there are always those
who insist that all who have been designing kit for years have got it
wrong.

Indeed it is rather similar to what was done with TV and monitor CRTs,
to interface the screen with people's living rooms at an appropriate
potential!


Hmmm, they must have done it differently over there. I've been bitten a
number of times by not being careful around the anode lead on a CRT.
The cathode is nearer ground potential because it's exposed on the back
of the tube.

You'd think being bitten by 25KV the first time would teach me a lesson.
But some people never learn :)

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

The "Two Transistor challenge" - taking things a bit too far?
 

On Tue, 18 Feb 2014, gareth wrote:

"Michael Black" wrote in message
news:alpine.LNX.2.02.1402181359580.14557@darkstar. example.org...
On Tue, 18 Feb 2014, gareth wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost nearly
a week's wages for the average working man, and so it was good economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the tens
of MegaHertz are now ten-a-penny, so what is achieved by competitions
such as the "Two Transistor Challenge" where it is the costs of switching
(manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they were
about "build a whole receiver using the same transistor type", or "build a
receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to you?) can
be operated with only 12V on the anode.

That's not new. There were some articles in the various hobby electronic
magazines in the fifties and sixties about running them at low voltage,
"starved circuits".

Of course, that was about the time when new tubes came along that could be
run off low plate voltage, a sort of last gasp before transistors took
over. You'd see such tubes in car radios in a very specific time span,
tubes for the RF stages, maybe in the IF but those might have been
transistors, and then the audio stage. That period when tubes weren't yet
really good at radio frequencies.

Or the COllins R392, that used 28v plate voltage.

The best "starved circuit" was an article by John W. Campbell (of science
fiction fame) in CQ in the late fifties. It was about running a CRT at
relatively low voltage in an oscilliscope. It drove up sensitivity so you
could do away with amplification for many purposes (and thus the scope was
broadband) but you lost deflection and I think brightness. The scheme
came out of Bell Labs, he mentioned some specially built CRTs for the
purpose that included magnifiers.

Michael

The "Two Transistor challenge" - taking things a bit too far?
 

On Tue, 18 Feb 2014, Brian Reay wrote:

On 18/02/14 20:21, Brian Howie wrote:
In message , Brian Reay writes

For the 'everyday' user, RPN was not popular and calculators offering,
almost, algebraic, entry became more popular. I think the first
calculator to offer true algebraic entry (ie following BODMAS/BIDMAS
convention) was Texas. Even today some cheap calculators don't follow
the convention. One of the many things I warn pupils of when I teach
calculator use.


I used a National Semiconductor 4640 RPN calculator for about 30 years.
So much so that I can't use a "normal" calculator. I've still got it but
it needs the charger socket and the batteries replaced.

RPN can't be beat for long chain calculations.


True.

Either way, RPN as the user interface has become a 'niche' market. Do HP
still offer RPN?

Yes, but they are still higher priced, so you'd be going out of your way
to buy one. I seem to recall seeing one in a flyer that could be switched
between RPN and "normal", which I suppose has advantages. But, if you have
both, I suspect the pull is towards "normal".

I have a minor collection of early scientific pocket calculators. Some
TI, including the one that could be hooked to a printer (and the printer).
And some HP, but the batteries don't keep a charge.

I should get one of the HP going, not only are they RPN, but they have LED
readouts, astonish people with the ancient technology. Just as soon as I
figure out how to get that battery clip back on my TI LED watch from 1977.

Michael

The "Two Transistor challenge" - taking things a bit too far?
 

Michael Black wrote:

What I find intriguing is the realisation that valves ("tubes" to you?) can
be operated with only 12V on the anode.

That's not new. There were some articles in the various hobby electronic
magazines in the fifties and sixties about running them at low voltage, "starved circuits".

Of course, that was about the time when new tubes came along that could
be run off low plate voltage, a sort of last gasp before transistors took
over. You'd see such tubes in car radios in a very specific time span,
tubes for the RF stages, maybe in the IF but those might have been
transistors, and then the audio stage. That period when tubes weren't
yet really good at radio frequencies.

Or the COllins R392, that used 28v plate voltage.

The best "starved circuit" was an article by John W. Campbell (of science
fiction fame) in CQ in the late fifties. It was about running a CRT at
relatively low voltage in an oscilliscope. It drove up sensitivity so
you could do away with amplification for many purposes (and thus the
scope was broadband) but you lost deflection and I think brightness. The
scheme came out of Bell Labs, he mentioned some specially built CRTs for
the purpose that included magnifiers.


Indeed Michael.

Anyone active on the home brew scene must have seen projects using valves
with low HT supplies, they were quite common and popular in the UK. I
expect someone with access to back issues of Radio Constructor could turn
up a couple per volume. RC was a popular, if slightly old style, magazine
which seemed to include more valve projects than the other magazines of the
day. Sadly, it is no more.

I think some valves were developed for use in 'Walkie Talkies' which were
baseless (ie were wire into circuit via flying leads not plugged into
sockets) and were designed to operate with a low HT.

There were also valves for hearing aids which were, I suspect, similar.

The "Two Transistor challenge" - taking things a bit too far?
 

On Tue, 18 Feb 2014 15:31:18 -0500, Jerry Stuckle wrote:

I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode :)

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At first
glance it sounds crazy - but it made for a very simple and efficient way
to couple the output of the magnetron to the waveguide.

Microwave ovens still do that. At least, my Toshiba does.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

The "Two Transistor challenge" - taking things a bit too far?
 

Michael Black wrote:
On Tue, 18 Feb 2014, Brian Reay wrote:

Either way, RPN as the user interface has become a 'niche' market. Do HP
still offer RPN?

Yes, but they are still higher priced, so you'd be going out of your way
to buy one. I seem to recall seeing one in a flyer that could be
switched between RPN and "normal", which I suppose has advantages. But,
if you have both, I suspect the pull is towards "normal".

HP calculators were always the most expensive, at least in the UK.

I think Casio probably have the bulk market sewn up. Anything you can't do
with one of their £8 scientifics (other than perhaps function plotting) is
probably something to do on a package.

I have a minor collection of early scientific pocket calculators. Some
TI, including the one that could be hooked to a printer (and the printer).
And some HP, but the batteries don't keep a charge.

I should get one of the HP going, not only are they RPN, but they have
LED readouts, astonish people with the ancient technology. Just as soon
as I figure out how to get that battery clip back on my TI LED watch from 1977.

I suppose I have an informal collection as I probably have all of my old
calculators.
I never reduced myself to a digital watch.

The "Two Transistor challenge" - taking things a bit too far?
 

On Tue, 18 Feb 2014 20:00:32 +0000, gareth wrote:

What I find intriguing is the realisation that valves ("tubes" to you?)
can be operated with only 12V on the anode.

You're thinking of the American way to do things. European car
manufacturers were slow to change to 12V electrical systems, so they used
tubes that worked with 6V on the plate. An example is the EF98, http://
http://www.mif.pg.gda.pl/homepages/f...030/e/EF98.pdf.

I've seen data sheets with even lower voltage ratings but I can't put my
finger on one right now.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.

The "Two Transistor challenge" - taking things a bit too far?
 

"Jerry Stuckle" wrote in message
...
On 2/18/2014 4:29 PM, Percy Picacity wrote:
In article , Brian Reay wrote:
On 18/02/14 20:31, Jerry Stuckle wrote:
There was a time, back inthe 1920s and 1930s, that any active device
(valves in them thar days, tubes for the leftpondians) would cost
nearly
a week's wages for the average working man, and so it was good
economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the
tens
of MegaHertz are now ten-a-penny, so what is achieved by
competitions
such as the "Two Transistor Challenge" where it is the costs of
switching (manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes they
were
about "build a whole receiver using the same transistor type", or
"build a receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to
you?) can be operated with only 12V on the anode.

No unusual at all.

Not only were a number of valves for the car radio (and possibly other)
markets available, I recall designs which use 'ordinary' valves with
6.3V AC heaters and a voltage doubler and rectifier to provide the "HT".
I recall a one valve design in Radio Constructor, which I build. It was
the 'cover article'. The design called for an Eddystone Box, far too
expensive, so I used a tin box from some short bread.

I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode :)

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At
first
glance it sounds crazy - but it made for a very simple and efficient
way
to couple the output of the magnetron to the waveguide.

No reason why it shouldn't be done. I can imagine some of the more
"technically challenged" struggling with it but there are always those
who insist that all who have been designing kit for years have got it
wrong.

Indeed it is rather similar to what was done with TV and monitor CRTs,
to interface the screen with people's living rooms at an appropriate
potential!

Hmmm, they must have done it differently over there. I've been bitten a
number of times by not being careful around the anode lead on a CRT. The
cathode is nearer ground potential because it's exposed on the back of the
tube.

You'd think being bitten by 25KV the first time would teach me a lesson.
But some people never learn :)

I was a 1960s TV engineer in the UK. 15kV or so on the CRT anode was normal.
The viewer was protected by a thick layer of glass that also formed an
implosion guard. Colour CRTs had around 25kV on the anode, and in early
models with anode currents of 1mA or so the line output stage was lead
shielded to reduce X-radiation. Happy days.
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk

The "Two Transistor challenge" - taking things a bit too far?
 

On 2/18/2014 7:06 PM, FranK Turner-Smith G3VKI wrote:
"Jerry Stuckle" wrote in message
...
On 2/18/2014 4:29 PM, Percy Picacity wrote:
In article , Brian Reay wrote:
On 18/02/14 20:31, Jerry Stuckle wrote:
There was a time, back inthe 1920s and 1930s, that any active
device
(valves in them thar days, tubes for the leftpondians) would
cost nearly
a week's wages for the average working man, and so it was good
economical
sense to try and use it as many ways as possible simultaneously.
Times have changes, and active devices with performance into the
tens
of MegaHertz are now ten-a-penny, so what is achieved by
competitions
such as the "Two Transistor Challenge" where it is the costs of
switching (manual, relays) which would be the major outlay?
Not carping, just curious.

There have always been "contests" like that, though sometimes
they were
about "build a whole receiver using the same transistor type", or
"build a receiver without any ICs" after ICs had come around.

What I find intriguing is the realisation that valves ("tubes" to
you?) can be operated with only 12V on the anode.

No unusual at all.

Not only were a number of valves for the car radio (and possibly other)
markets available, I recall designs which use 'ordinary' valves with
6.3V AC heaters and a voltage doubler and rectifier to provide the
"HT".
I recall a one valve design in Radio Constructor, which I build. It was
the 'cover article'. The design called for an Eddystone Box, far too
expensive, so I used a tin box from some short bread.

I remember back in the 70's we had radar sets with ZERO volts on the
magnetron's anode (DC ground). Of course, there was -3KV or so on the
cathode :)

I haven't done anything with radar in well over 30 years, so I don't
know if they still do it or not. But I wouldn't be surprised. At
first
glance it sounds crazy - but it made for a very simple and
efficient way
to couple the output of the magnetron to the waveguide.

No reason why it shouldn't be done. I can imagine some of the more
"technically challenged" struggling with it but there are always those
who insist that all who have been designing kit for years have got it
wrong.

Indeed it is rather similar to what was done with TV and monitor CRTs,
to interface the screen with people's living rooms at an appropriate
potential!

Hmmm, they must have done it differently over there. I've been bitten
a number of times by not being careful around the anode lead on a CRT.
The cathode is nearer ground potential because it's exposed on the
back of the tube.

You'd think being bitten by 25KV the first time would teach me a
lesson. But some people never learn :)

I was a 1960s TV engineer in the UK. 15kV or so on the CRT anode was
normal. The viewer was protected by a thick layer of glass that also
formed an implosion guard. Colour CRTs had around 25kV on the anode, and
in early models with anode currents of 1mA or so the line output stage
was lead shielded to reduce X-radiation. Happy days.

Yup, same here. Except when you jig the chassis up for testing, the
anode lead is basically hanging in the air. Also, the CRT makes a great
capacitor - if you don't discharge it enough times before disconnecting
the anode lead, it can still set you back on your backside :)

--
==================
Remove the "x" from my email address
Jerry, AI0K

==================