Zener noise / oscillations

If only!

The only monitor I designed incorporated width modulation using a Darlington series regulator controlling the voltage to the HO stage, with feedback derived from beam current. Rock steady size with a raster half height peak white, half black. That used a diode-split FBT.

Consumer designs (yecch!), using transistors, used a cheapo arrangement of a resistor in series with the supply, so the scan decreased with increased current draw, compensating for the increase in deflection sensitivity when the HV went down with increased beam current. Not perfect, but good enough for consumer TV.

Triplers were superseded by diode split windings, sometime in the 1980s.

Tube HO drive looked like a pulse with a (small) ramp sitting on top. That went away when tubes did. Transistor drive is just a rectangular pulse. Don't forget, also, that the output device (tube or transistor) is on only during the second half of the forward scan. The first half is supplied by the stored energy in the inductance circulating via the efficiency diode, both for tubes and transistors.

The thyristor HO scheme, developed by Siemens, was *really* weird, with a separate commutating coil. but still using Blumlein's inductive flyback principle for the actual scan. I had the original application notes, but they've long gone.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse
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Freudian slip?

;-)

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Reply to
Fred Abse

All my 7000 series have green P31 phosphors, with blue filters. Background looks blue. Even the 7104, with an MCP CRT. I do have a 7603 storage that only ever gets used with spectrum analyzer plugins. That has a P31 phosphor, with a yellow (ish) filter, similar, I suppose to yours.

I guess I'm just so used to blue filters, I assume everything uses them.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Aren't all "Zeners" above ~5.6V actually avalanche diodes?

Reply to
krw

Somewhere around there.

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Reply to
Fred Abse

Yes, but everybody still calls them zeners.

--

John Larkin                  Highland Technology Inc
www.highlandtechnology.com   jlarkin at highlandtechnology dot com   

Precision electronic instrumentation
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Reply to
John Larkin

It makes a difference when you're discussing negative resistance, which accompanies avalanche breakdown, but not, AFAIK, zener breakdown.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)
Reply to
Fred Abse

Too tired to look at what I typed. I haven't slept more than four hours a night, in over a year. Sometimes I forget to hit the spell check button.

OTOH, I have seen more than one rectifier on fire. Big, stinking Selenium stacks with flames & sparks shooting out all over the place.

Reply to
Michael A. Terrell

radiation.

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That is (obviously) glass and not metal and is small; looks similar to their GV3A; the catalog easily available online (courtesy of Syd Levine of Analog Services) does not list the HV series.

Reply to
Robert Baer

There is NO transistor that can take 1500V reliably; and at $2 each? FURRgeddit sez the FURRy Baer.

Reply to
Robert Baer

Oh, i remember them well; to use _that_ effect is way off datasheet specs.

Reply to
Robert Baer

Misspelt: s/b RectumFier with preparation H.

Reply to
Robert Baer

Check; yellowish phosphor and orangish graticule. I invert colors to be more readable and less ink to print; can convert then to B&W for "publication" if need.

Reply to
Robert Baer

Check. Helps to make for confusion.

Reply to
Robert Baer

Yea, did not look at very many

Reply to
Robert Baer

  • He wore THOSE??

Reply to
Robert Baer

On a sunny day (Mon, 30 Jul 2012 21:48:16 -0700) it happened Robert Baer wrote in :

I am sure I had some? google: transistor Vce 1500

Hundreds of links

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switching transistor Ic 5A-datasheet.html

The ones I had (or have, seen some recently in a box) are for TV horizontal output. Large current, fast switching, low beta. Probably not suited for low current stabilizer. But they do exist.

Reply to
Jan Panteltje

output.

This is the highest voltage one that Digikey has in stock (I think, anyway)

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Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

output.

Here's one I've never seen the likes of before. Vcs (not a typo!) 2200V

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Reply to
JW

output.

Cascodes!

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Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

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