Topics

In Defense of the 7A19 + Ode to the 555 Triple Nickel


 

Hi Andy,
Thank you for that link to the article on Trigger Circuits by Dennis Feucht. It turns out he worked at Tek from 1967 to 1985. The article was a quick read and it was the first time I read about how the various trigger implementations were done. I always took for granted the time base mode switch options (AUTO, NORM, and P to P AUTO) until I read this and learned how they work. So it was nice to see them explained. He created another trigger mode he named AUTO-LEVEL which I don't think I have ever used.
It turns out he loves his Tek 555 "Triple Nickel" dual beam scope and he even wrote a clever poem to it which I included below for all our members who love their 555's.

The Jim Williams chapter on Vertical Amplifiers was written by a close friend of mine with a very impressive career at Tek. He has17 patents from Tek. He designed many different (superb) things like the 067-0681-01 Tunnel Diode Pulse Generator, The 7A11 250MHz FET Input Vertical plugin, The 25pSec Push Pull Pulse Generator (I have one of 20 he made), The 485 vertical amplifier, the 7A29 1GHz Vertical Plugin.

Dennis Tillman W7pF

Dennis Feucht's "Ode to the 555 Oscilloscope"

You've heard the story of the bandwidth race,
Where ‘scopes and counters were setting the pace;
Well that story is true, I'm here to say;
I was using a 555A.
It's got a graticule, all lit up,
That front-panel claptrap makes it look tough.
It's got plug-ins, uses ‘em all;
Has snappy risetime, and also fall.
With a dual-beam display at reasonable cost,
And forty-eleven knobs, you can really get lost;
It's got a dual-delayed timebase, but I ain't scared,
The trace is sharp; the probes are fair.
Pulled out a new project late one night,
The test equipment was burning bright,
I started driving a wideband amp,
To see which stage I needed to damp.
When all of a sudden in the blink of an eye
A jumble of waveforms passed me by,
And I said, “Wow, that's a marvel to me!”
Pretty soon a square-wave was all I could see.
Now the waveform time-scale made no sense;
The scope display looked like a picket fence.
I slowed it down and was glad to know
That it wouldn't alias like a DSO.
Now the boss was ribbing me for being behind,
So I thought I'd make the probes unwind;
Took the volts per div knob, and man alive!
I cranked it up to a setting of five.
Powered the wideband amp again,
And drove it with a function gen,
Set the amplitude knob to three or four,
The levels were hitting the ceiling and floor.
Smoke was coming from out of the load
When I set the trigger to hf mode;
The power bandwidth was looking right;
Nearly approaching the speed of light.
I tweaked the circuit here and there,
Replaced a cap and transistor pair;
Got the speed I needed with room to go;
Manufacturing would be glad to know.
The task was finished, the specs first-rate,
The customers called, said the amp worked great;
I got a promotion, moved out of L.A.,
And I credit success to that '55A!

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Andy Warner
Sent: Monday, June 01, 2020 9:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In Defense of the 7A19

Doesn't speak to HP vs Tek triggering circuits, but does provide some interesting basic insight into the process and considerations:
https://www.planetanalog.com/oscilloscope-trigger-generators-precision-synchronizers/

Like most things on a 'scope (or good engineering in general), if they are done well, as users we don't have much reason to think that the implementation may be complex and subtle.

A case in point is Chapter 7 of "The Art and Science of Analog Circuit Design" edited by Jim Williams. This chapter is titled "Signal Conditioning in Oscilloscopes and the Spirit of Invention", authored by Steve Roach, then of HP. Read that and you gain a whole new respect every time you see the trace you want on the screen of a scope.
Also recommended is Chapter 14 of "Analog Circuit design", also edited by Jim Williams (can anyone detect a theme here) - "Good Engineering and Fast Vertical Amplifiers" by John Addis of Tek.

On Mon, Jun 1, 2020 at 11:22 AM Dave Daniel <kc0wjn@...> wrote:

Well, if you can get a schematic for the HP ‘scope, you might be able
to figure out why the HP trigger circuit works differently than a
Tektronix trigger circuit by comparing them. Perhaps Dennis can tell
us the model number of the HP ‘scope that was used in the demo.

I, too, need to re-read the Tektronix books now that I am retired.

DaveD

On Jun 1, 2020, at 11:55, Michael W. Lynch via groups.io <mlynch003=
yahoo.com@groups.io> wrote:

Dave,

I am going to re-read this once again, if only to clarify how the
TEK
Trigger Circuit operated.

I was mainly concerned with how HP did it versus TEK. Obviously a
"TEK
Concepts" document will not go into how HP out performed the TEK Circuit.

As Dennis has suggested, It is quite possible that HP tuned their
circuit to work really well in a situation where the TEK scope
performed much less accurately.

There is a good chance that we may never know the answer to this.

Thanks!

--
Michael Lynch
Dardanelle, Arkansas




--
Andy





--
Dennis Tillman W7pF
TekScopes Moderator


John G
 

For anyone else that knew this sounds familiar, it's a great take off of Commander Cody and His Lost Planet Airmen song Hot Rod Lincoln.


 

That is exactly what he had in mind when he wrote it.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John G
Sent: Monday, June 01, 2020 3:52 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In Defense of the 7A19 + Ode to the 555 Triple Nickel

For anyone else that knew this sounds familiar, it's a great take off of Commander Cody and His Lost Planet Airmen song Hot Rod Lincoln.





--
Dennis Tillman W7pF
TekScopes Moderator


Dave Daniel
 

Dennis,

I didn't notice that this was written by Dennis Feucht. Dennis published a book, "Handbook of Analog Circuit Design".

Many years ago, I tried to find a copy of this book. I finally found a used copy by contacting Dennis directly, who either provided me a copy or led me to  a copy (I forget which).

Do not search for "feucht" on the internet.

Dennis is also heavily into model rocketry, something I experimented with when  was in high school.

Dennis' original revision contains a number of errors. He has since re-published an updated copy of the book, available as a five-volume set or, apparently, a new hardback edition. It is terse and approaches analog design  from a unique perspective, t is a good book to have.

I communicated with Dennis around the time that he re-published his five-volume set and convinced him to send to me PDF copies of the volumes, which I still have and still use as a reference. I promised Dennis that I would never release copies of those PDFs.

For anyone interested in analog design, I highly recommend Dennis' book(s).

DaveD

On 6/1/2020 6:01 PM, Dennis Tillman W7pF wrote:
Hi Andy,
Thank you for that link to the article on Trigger Circuits by Dennis Feucht. It turns out he worked at Tek from 1967 to 1985. The article was a quick read and it was the first time I read about how the various trigger implementations were done. I always took for granted the time base mode switch options (AUTO, NORM, and P to P AUTO) until I read this and learned how they work. So it was nice to see them explained. He created another trigger mode he named AUTO-LEVEL which I don't think I have ever used.
It turns out he loves his Tek 555 "Triple Nickel" dual beam scope and he even wrote a clever poem to it which I included below for all our members who love their 555's.

The Jim Williams chapter on Vertical Amplifiers was written by a close friend of mine with a very impressive career at Tek. He has17 patents from Tek. He designed many different (superb) things like the 067-0681-01 Tunnel Diode Pulse Generator, The 7A11 250MHz FET Input Vertical plugin, The 25pSec Push Pull Pulse Generator (I have one of 20 he made), The 485 vertical amplifier, the 7A29 1GHz Vertical Plugin.

Dennis Tillman W7pF

Dennis Feucht's "Ode to the 555 Oscilloscope"

You've heard the story of the bandwidth race,
Where ‘scopes and counters were setting the pace;
Well that story is true, I'm here to say;
I was using a 555A.
It's got a graticule, all lit up,
That front-panel claptrap makes it look tough.
It's got plug-ins, uses ‘em all;
Has snappy risetime, and also fall.
With a dual-beam display at reasonable cost,
And forty-eleven knobs, you can really get lost;
It's got a dual-delayed timebase, but I ain't scared,
The trace is sharp; the probes are fair.
Pulled out a new project late one night,
The test equipment was burning bright,
I started driving a wideband amp,
To see which stage I needed to damp.
When all of a sudden in the blink of an eye
A jumble of waveforms passed me by,
And I said, “Wow, that's a marvel to me!”
Pretty soon a square-wave was all I could see.
Now the waveform time-scale made no sense;
The scope display looked like a picket fence.
I slowed it down and was glad to know
That it wouldn't alias like a DSO.
Now the boss was ribbing me for being behind,
So I thought I'd make the probes unwind;
Took the volts per div knob, and man alive!
I cranked it up to a setting of five.
Powered the wideband amp again,
And drove it with a function gen,
Set the amplitude knob to three or four,
The levels were hitting the ceiling and floor.
Smoke was coming from out of the load
When I set the trigger to hf mode;
The power bandwidth was looking right;
Nearly approaching the speed of light.
I tweaked the circuit here and there,
Replaced a cap and transistor pair;
Got the speed I needed with room to go;
Manufacturing would be glad to know.
The task was finished, the specs first-rate,
The customers called, said the amp worked great;
I got a promotion, moved out of L.A.,
And I credit success to that '55A!

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Andy Warner
Sent: Monday, June 01, 2020 9:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In Defense of the 7A19

Doesn't speak to HP vs Tek triggering circuits, but does provide some interesting basic insight into the process and considerations:
https://www.planetanalog.com/oscilloscope-trigger-generators-precision-synchronizers/

Like most things on a 'scope (or good engineering in general), if they are done well, as users we don't have much reason to think that the implementation may be complex and subtle.

A case in point is Chapter 7 of "The Art and Science of Analog Circuit Design" edited by Jim Williams. This chapter is titled "Signal Conditioning in Oscilloscopes and the Spirit of Invention", authored by Steve Roach, then of HP. Read that and you gain a whole new respect every time you see the trace you want on the screen of a scope.
Also recommended is Chapter 14 of "Analog Circuit design", also edited by Jim Williams (can anyone detect a theme here) - "Good Engineering and Fast Vertical Amplifiers" by John Addis of Tek.

On Mon, Jun 1, 2020 at 11:22 AM Dave Daniel <kc0wjn@...> wrote:

Well, if you can get a schematic for the HP ‘scope, you might be able
to figure out why the HP trigger circuit works differently than a
Tektronix trigger circuit by comparing them. Perhaps Dennis can tell
us the model number of the HP ‘scope that was used in the demo.

I, too, need to re-read the Tektronix books now that I am retired.

DaveD

On Jun 1, 2020, at 11:55, Michael W. Lynch via groups.io <mlynch003=
yahoo.com@groups.io> wrote:
Dave,

I am going to re-read this once again, if only to clarify how the
TEK
Trigger Circuit operated.
I was mainly concerned with how HP did it versus TEK. Obviously a
"TEK
Concepts" document will not go into how HP out performed the TEK Circuit.
As Dennis has suggested, It is quite possible that HP tuned their
circuit to work really well in a situation where the TEK scope
performed much less accurately.
There is a good chance that we may never know the answer to this.

Thanks!

--
Michael Lynch
Dardanelle, Arkansas



--
Andy




--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


Jim Ford
 

Yeah, I remember Dennis Feucht writing that it was sung to the tune of Hot Rod Lincoln. Back in EDN or Electronic Design or EETimes, somewhere I don't recall anyway.

Jim Ford

------ Original Message ------
From: "John G" <mnjgfl@...>
To: TekScopes@groups.io
Sent: 6/1/2020 3:51:58 PM
Subject: Re: [TekScopes] In Defense of the 7A19 + Ode to the 555 Triple Nickel

For anyone else that knew this sounds familiar, it's a great take off of Commander Cody and His Lost Planet Airmen song Hot Rod Lincoln.



Randy Newman
 

Hi Dennis. Just had to chime in on the 555 bandwagon. While it is not (by far) the fastest scope I own, it is in ways the most impressive, however it’s feature I most appreciate is it’s clear fine-line trace. Mine also has the purple-blue phosphor (which, if I remember correctly is the one especially suited to photographic use).
I have used 16GHz Tek DSO’s at work, which are cool, but still love my 555.


 

Hi Randy,
The trace sharpness was a hallmark of Tek scopes. The increased bandwidth, high writing rate, and very fast sweep speeds of the 7000 series necessitated higher acceleration voltages. 7000 CRTs would have to be so long (up to 7') they would be impractical unless a way could be found to solve this problem.
The solution Tek came up with was the Domed (Expansion) Mesh which unfortunately expands the beam width.
It was an engineering tradeoff.

The 7104 CRT does not use an domed mesh. It uses a scan expansion lens and a spot demagnification lens.
You can read more about all the tradeoffs that have to be taken into account here
https://vintagetek.org/wp-content/uploads/2017/11/Electronic-Design-Jan-18-1979.pdf
and here
https://vintagetek.org/wp-content/uploads/2017/11/Tekscope_1979_V11_N1.pdf

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Randy Newman
Sent: Wednesday, June 17, 2020 8:58 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In Defense of the 7A19 + Ode to the 555 Triple Nickel

Hi Dennis. Just had to chime in on the 555 bandwagon. While it is not (by far) the fastest scope I own, it is in ways the most impressive, however it’s feature I most appreciate is it’s clear fine-line trace. Mine also has the purple-blue phosphor (which, if I remember correctly is the one especially suited to photographic use).
I have used 16GHz Tek DSO’s at work, which are cool, but still love my 555.





--
Dennis Tillman W7pF
TekScopes Moderator