On 19/02/2014 09:32, gareth wrote:
"AndyW" wrote in message
...

(but then I enjoy retro-tech like making Baird televisors)


Mirror-drum, or Nipkow disk?

Nipow disk. I built my first one while at school using plans in Hobby
Electronics using my sister's 'The Partridge Family Album' LP, I thought
that it was the best use that it could be put to; she disagreed.

One of my later ones used a 'conveyer belt' instead of a disk which
produces a square screen.

LED or nitro-benzine as the polariser?

Polariser?
I used a neon as my light source, I didn't have any polarisation.
My later ones use LEDs at light sources and produce a much better
quality of image.

Andy

"AndyW" wrote in message
...
On 19/02/2014 09:32, gareth wrote:

LED or nitro-benzine as the polariser?
Polariser?

To my eternal regret, because I disposed of them 38 years ago, I had a
pile of "Amateur Wireless" from the 1930s within which were designs
for mirror-drum scanners, and the modulation was not by a neon light
but with a constant light source which was then modulated by a series
of polarising filters, with one being variable to rotate the polarisation.

ISTR (38 years ago!!!) that the liquid used was nitro-benzene

On 20/02/2014 11:51, gareth wrote:
"AndyW" wrote in message
...
On 19/02/2014 09:32, gareth wrote:

LED or nitro-benzine as the polariser?
Polariser?

To my eternal regret, because I disposed of them 38 years ago, I had a
pile of "Amateur Wireless" from the 1930s within which were designs
for mirror-drum scanners, and the modulation was not by a neon light
but with a constant light source which was then modulated by a series
of polarising filters, with one being variable to rotate the polarisation.

ISTR (38 years ago!!!) that the liquid used was nitro-benzene

OK I follow you now. I had a quick google and found out about
nitrobenzene and modulating polarisation. Never heard of it before. Live
and learn.

My original set up was as simple and agricultural as they come, vinyl
LP, scrap motor from a cassette player, Neon attached to am amplifier
behind the 'screen' and a camera made from a lens and an LDR recording
onto a cassette player - the bandwidth was low enough to record on audio.

My latest televisor was made from a circle of black plastic spinning on
a hand fan with a very small torch behind it modulated by the sound from
a small mp3 player. It all folds up and fits in a pocket.

Andy

On Wed, 19 Feb 2014, AndyW wrote:

On 18/02/2014 10:58, 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 is something challenging about restricting your resources.
My most memorable receiver I ever built was made from a toilet roll tube,
wire, a crystal earpiece, tinfoil and paper hand-rolled capacitor and some
galena crystal as a detector.
I think I got more satisfaction out of that that I ever did from a digitally
programmable oscillator based beast.

I think that's something that may be lost.

People lament that in this day and age, it's difficult to attract the
young to the hobby, because how can it compete with the Internet?

And you don't compete with it, you show off things that are unique.

A simple project for a beginner is identical to what it was forty or fifty
years ago, a first project and when it actually gets working, what an
accomplishment. It's not because the simple project is comparable with the
electronic wonders of the 21st century, it's that you built it and it
worked.

Michael

On 19/02/2014 16:30, Michael Black wrote:


A simple project for a beginner is identical to what it was forty or
fifty years ago, a first project and when it actually gets working, what
an accomplishment. It's not because the simple project is comparable
with the electronic wonders of the 21st century, it's that you built it
and it worked.

Absolutely true. One of my foundation types constructed a simple bit of
circuitry to comply with the course.
He rang me afterwards in a state of excitement - "It works - it bloody
works!" he exclaimed.

Les.

On 19/02/2014 16:30, Michael Black wrote:
On Wed, 19 Feb 2014, AndyW wrote:

On 18/02/2014 10:58, 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 is something challenging about restricting your resources.
My most memorable receiver I ever built was made from a toilet roll
tube, wire, a crystal earpiece, tinfoil and paper hand-rolled
capacitor and some galena crystal as a detector.
I think I got more satisfaction out of that that I ever did from a
digitally programmable oscillator based beast.

I think that's something that may be lost.

People lament that in this day and age, it's difficult to attract the
young to the hobby, because how can it compete with the Internet?

Because I am a bit of a geek I get asked to run Jamboree on the Internet
for my local scout group in October (been doing it for about 10 years now).
When we have computers set up for text chat, chat rooms, voip, skype
video chat and multi participant video conferencing the kids are simply
not interested in talking on the radio. They can get crystal clear
communication and don't really care about some faint HF chat.

It is sad but to compete radio has to offer something new or different.
I would like to get them to build simple qrp sets and use WSPR to see
how far they can reach and also see how far they can communicate on qrp
with morse (albeit with some help).
They simply cannot make an internet capable computer and OS but they can
make a QRP set like a pixie on a breadboard in an hour and be picked up
around the world on WSPR.
Catch that buzz and then it is a short step to (very slow) morse
communication and hopefully getting them hooked.

And you don't compete with it, you show off things that are unique.

A simple project for a beginner is identical to what it was forty or
fifty years ago, a first project and when it actually gets working, what
an accomplishment. It's not because the simple project is comparable
with the electronic wonders of the 21st century, it's that you built it
and it worked.

I was asked to run a technology based badge for some scouts and had them
making crystal radios, some of them swore blind that it could not work
because there were no batteries despite building it themselves and hand
winding the coils.
The reaction by many is pure amazement that a bundle of wire and junk
can receive a radio station, it remind me of the buzz I first got as a
kid making a crystal set from plans in the eagle annual (I'm not old
enough to get one from new, I bought it in a jumble sale in the 70s)

The buzz is still there if you get them young enough and pre internet chat.

Andy

On 2014-02-18, 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?


I remember my first home build radio: a earphone with just a 1N34 diode
in
parallel, an outdoor antenna and a good ground. Lots of listening hours of
a nearby AM 1230 KHz transmiter.

With a single FET regenerative receiver I could listen shorwave radios
from all over the world.

I like to work with very simple electronic equipment: I am reading and
replying to this news group with a 20 MHz 80286, 1 MBy memmory and all
programs in a 1.44
diskette (no Hard Drive).

Alejandro Lieber
LU1FCR
Rosario Argentina

--

SDF Public Access UNIX System - http://sdf.org

On 2/26/2014 11:09 AM, Alejandro Lieber wrote:
On 2014-02-18, 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?


I remember my first home build radio: a earphone with just a 1N34 diode
in
parallel, an outdoor antenna and a good ground. Lots of listening hours of
a nearby AM 1230 KHz transmiter.

With a single FET regenerative receiver I could listen shorwave radios
from all over the world.

I like to work with very simple electronic equipment: I am reading and
replying to this news group with a 20 MHz 80286, 1 MBy memmory and all
programs in a 1.44
diskette (no Hard Drive).

Alejandro Lieber
LU1FCR
Rosario Argentina


I can understand this. Back in Junior High (middle school nowadays), my
parents got me an electronics projects kit. It used a 1T4 for the
active element; a D cell provided filament voltage and a 45V battery
(looked like a long 9V battery) provided the plate voltage.

I built all kinds of things from the examples, including regen
receivers. I spent hundreds of hours with it - probably one of the best
money my parents spent to keep me out of trouble . It was advanced
enough to keep me occupied, yet simple enough that it taught me a lot
about how more advanced (at least to me, at the time) circuits work.

I still like the simple electronics. However, simple receivers like
that just won't work for me now. Something about the 5KW AM transmitter
in my back yard...

There is a lot to be said for simplicity!

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

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

"Jerry Stuckle" wrote in message
...

I still like the simple electronics. However, simple receivers like that
just won't work for me now. Something about the 5KW AM transmitter in my
back yard...

The same for me 50 years ago. Home town was Portishead, and the TXs of
the international shipping Portiishead Radio were half a mile away across
the valley!

On 2/26/2014 12:32 PM, gareth wrote:
"Jerry Stuckle" wrote in message
...

I still like the simple electronics. However, simple receivers like that
just won't work for me now. Something about the 5KW AM transmitter in my
back yard...

The same for me 50 years ago. Home town was Portishead, and the TXs of
the international shipping Portiishead Radio were half a mile away across
the valley!




What 1/2 mile? I'm talking 50 yards (at the most) from my house to
their nearest tower.

My back yard (a pretty standard U.S. city lot from the 60's) directly
abuts their transmitter field. Their ground plane wires run right up to
the fence.

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

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