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'[EE]: Digital voltmeter from 1960'
2007\05\22@184526 by Peter P.

picon face
A real gem. Pity there is no schematic available:

 http://www.wps.com/projects/instruments/Cubic-V45/index.html

Peter P.


2007\05\23@085743 by Michael Rigby-Jones

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Fascinating instrument, a real gem as you say.  I'm not sure I agree with the authors suggestion that "Display technology has improved only slightly" though!

Regards

Mike


{Quote hidden}

>-

2007\05\23@102119 by Tony Smith

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> >A real gem. Pity there is no schematic available:
> >
> >  www.wps.com/projects/instruments/Cubic-V45/index.html
> >
> >Peter P.
> >
> Fascinating instrument, a real gem as you say.  I'm not sure
> I agree with the authors suggestion that "Display technology
> has improved only slightly" though!
>
> Regards
>
> Mike


What to do when Nixies haven't been invented yet.  Years ago I came across
Nixies, and figured I could emulate the display by, you guessed it, etching
numbers in glass, edge lit & stacked.  Worked nicely as a clock, and I was
suitably chuffed at my technical progress.

I was less chuffed when I discovered voltmeters like this, and even less
when I found out the Russians did it 30 or so years before that.

I've been meaning to make a 7 seg version, you only need 7 pieces of
glass/plastic per digit then.

Tony

2007\05\23@111207 by Michael Rigby-Jones

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{Quote hidden}

If you had enough sheets you could even make a dot matrix display :-)

Mike

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2007\05\23@114306 by Tony Smith

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{Quote hidden}

That thought had not occurred to me.  Probably a good thing.

Hmmm.

7 thin strips, a dot on each, being one vertical line.  5 strips for a
typical display, so 35 pieces.  A clock needs at least 4 displays, so that's
4 x 5 x 7, or 140 pieces.  With LEDs @ 20mA, that's pushing 3 amps.

It's hard to cut thin strips of glass, 5mm should be ok.  Assembled would be
35 x 25mm per 'number'.

Bi-colour can be done by having a LED at each end of the glass strip (window
glass is 3mm, for pictures it's 2mm).  Gosh, where would I find a 2 x 5mm
LED?

I'll add it to the pile.  Don't expect much progress  :)

Tony

2007\05\23@115330 by PAUL James

picon face

Tony,

You could reduce the current consumption by multiplexing the dots within
each digit, and
Multiplexing each digit.   Or you could have each digit on all the time
and just multiplex
Dots within each digit.  That would effectively be the same as 4 LED's.
Ie 4 Led's at @20ma
would be less than .1A.  Much more acceptable.


Regards,

       
Jim  

{Original Message removed}

2007\05\23@122313 by Richard

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I like to see the old technology but it is something you would really use?
It is easy enough to get or build a 6-digit voltmeter today.


{Original Message removed}

2007\05\23@141158 by Peter P.

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Richard <rgrazia1 <at> rochester.rr.com> writes:

> I like to see the old technology but it is something you would really use?
> It is easy enough to get or build a 6-digit voltmeter today.

Artsy and display objects are still using arcane display methods. Man-height
digits or starburst letters on a budget ? No problem.

Peter P.


2007\05\23@214016 by Jake Anderson

flavicon
face

> That thought had not occurred to me.  Probably a good thing.
>
> Hmmm.
>
> 7 thin strips, a dot on each, being one vertical line.  5 strips for a
> typical display, so 35 pieces.  A clock needs at least 4 displays, so that's
> 4 x 5 x 7, or 140 pieces.  With LEDs @ 20mA, that's pushing 3 amps.
>
> It's hard to cut thin strips of glass, 5mm should be ok.  Assembled would be
> 35 x 25mm per 'number'.
>
> Bi-colour can be done by having a LED at each end of the glass strip (window
> glass is 3mm, for pictures it's 2mm).  Gosh, where would I find a 2 x 5mm
> LED?
>
> I'll add it to the pile.  Don't expect much progress  :)
>
> Tony
>

you could probably hack something up with 5+7 sheets.
etch lines rather than dots and activate a horizontal + vertical line at the
same time to make the "dot" light up (brighter than the rest of the line).
scan through them and you should be done, It would be funky to see anyway.

2007\05\24@030355 by KPL

picon face
Actually I have old digital frequency counter from 70-ties, which is
still working fine and is even getting used sometimes, since my
pic-based counter is not finished:)
Nice tool, built completely on discrete components, no IC's. Nixie
indicators, even some kind of connector for remote control.
A bit frightening to see _that_ amount of cards inside, full of diodes
and transistors.
There is temperature controlled heated, insulated frequency source for
better stability.

--
KPL

2007\05\24@071444 by Tony Smith

picon face
{Quote hidden}

The problem is all the other lines light up too, not as bright as the main
one though.  That's why you have the 'one dot, one bit of glass' thing.

Could still make a cool display though.  A gauge springs to mind.

If you do want to make some, use plastic rather than glass, much easier to
work with.  Plastic also comes with a protective covering, any tiny
scratches you make will show up.  Very annoying.  You also need to paint the
edges of the bits to stop the light leaking out into other panels.  Not hard
to do, just a bit tedious.

One tip I came across was to glue or epoxy the LED to the plastic.  You lose
a lot of light in the 'air gap' as it tends to bounce off the edge of the
plastic, not go inside like it's supposed to.  

Agilent have a very nice PDF on making light pipes on their website
somewhere.  Drilling holes in the LED to insert a fibre optic cable as close
to the die as possible is going a little too far though  :)

Tony

2007\05\24@152103 by Rich

picon face
Who is the manufacturer?
----- Original Message -----
From: "KPL" <kpl.listesspamspam_OUTgmail.com>
To: "Microcontroller discussion list - Public." <@spam@piclistKILLspamspammit.edu>
Sent: Thursday, May 24, 2007 3:03 AM
Subject: Re: [EE]: Digital voltmeter from 1960


{Quote hidden}

> --

2007\05\24@155518 by KPL

picon face
It was made in ussr. I do not have it nearby now, may be I can
photograph it if I will remember.
Actually almost all equipment that is affordable for amateurs here, is
old russian stuff. But quite often those are good tools.

Btw, is anybody using this technique nowadays, like heated frequency
sources? It would be much easier now, with peltier elements and some
kind of integral regulator. I have seen audio amplifier IC used for
this regulator somewhere.


On 5/24/07, Rich <KILLspamrgrazia1KILLspamspamrochester.rr.com> wrote:
> Who is the manufacturer?
> {Original Message removed}

2007\05\24@210535 by Rich

picon face
Crystal ovens have been used since at least 1940. Probably longer.

----- Original Message -----
From: "KPL" <RemoveMEkpl.listesTakeThisOuTspamgmail.com>
To: "Microcontroller discussion list - Public." <spamBeGonepiclistspamBeGonespammit.edu>
Sent: Thursday, May 24, 2007 3:55 PM
Subject: Re: [EE]: Digital voltmeter from 1960


{Quote hidden}

> --

2007\05\25@002827 by Harold Hallikainen

face
flavicon
face

> Btw, is anybody using this technique nowadays, like heated frequency
> sources? It would be much easier now, with peltier elements and some
> kind of integral regulator. I have seen audio amplifier IC used for
> this regulator somewhere.

I think crystal ovens are still a good idea for ultimate stability. You
can temperature compensate a crystal oscillator, but it's probably better
to just hold it at a constant temperature. I remember seeing a "clamp on
crystal oven" years ago that was, I think, made by CTS. It was a PTC
thermistor that attached to the crystal. Put a fixed voltage across the
thermistor and it self heated the crystal to a fixed temperature.

Another constant temperature device is the LM399H voltage reference. I
think it's good for something like 0.5ppm/K . It's probably one of the
most stable references around. It heats the reference diode to some
constant temperature.

Harold


--
FCC Rules Updated Daily at http://www.hallikainen.com - Advertising
opportunities available!

2007\05\25@151823 by Walter Banks
picon face


Tony Smith wrote:

{Quote hidden}

I spent a summer working at a government calibration lab in the 60's one of the
digital voltmeters in that lab had an interesting display. A motor drove a drum
with 4 strips of the numbers 0..9 on it. The drum was spun and a strobe
assigned to each digit illuminated the designed number when it passed the
display window. It actually worked quite well was reasonably accurate
but had an annoying hum when running.

w..



2007\05\29@201512 by Peter P.

picon face
Peter P. <plpeter2006 <at> yahoo.com> writes:

> A real gem. Pity there is no schematic available:
>
>   http://www.wps.com/projects/instruments/Cubic-V45/index.html

Are the schematics of these devices really gone ? The article says that the unit
used only 27 transistors. I am *dying* to see a DVM schematic that uses 27
transistors and is accurate to 5 displayed digits. Where would one look for such
paperwork ?

The device described by Walter Banks is also very interesting. The spinning drum
illuminated by a strobe was used before that for sonar and depth sounder display
afaik. The National sonar chip (I don't remeber the code, it was in the special
functions section in old catalogs) also expected to drive a similar display,
with a neon strobe.

Peter P.


2007\05\29@203754 by Jinx

face picon face
> The National sonar chip (I don't remeber the code, it was in the special
> functions section in old catalogs) also expected to drive a similar
display,
> with a neon strobe.

My 1988 NS Linear Book 3, now full of obsoleted parts, suggests
LM1812

www.chipdocs.com/datasheets/datasheet-pdf/National-Semiconductor/LM18
12.html

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