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Anyone interested a addon plugin that enable you to use 7000 plugins on modern digital scope


ycui7
 

I am working on a project that generating all the necessary power for a 7000 plugins, so that you can use some 7000 plugins on modern digital oscilloscope.

https://groups.io/g/TekScopes/album?id=246549

The addon board will be installed on the back of 7000 plugins, generating +/-50V, +/-17V, and +/-5V. It also has capability yo convert the plugin's differential output to single-ended signal for consumption by modern digital scope.

Power will be provided by 20V USB-PD and converted to all requried voltage for 7000 plugins.

The current targeting 700 plug-ins are:
7A13
7A22
7S14 (requires two addon boards)
7S12 (requires two addon boards)


Anyone interested in this?


Leo Potjewijd
 

I would be.
Looks like a pretty neat design, too.
What would you make available?


Ed Breya
 

What are you going to do about the plug-in edge connector? Have you found a standard type that will work?

Ed


Ke-Fong Lin
 

Hi Yang and Ed,

Yang, I'm definitely interested. My "target" plug-ins would 7A22 differential amplifier and 7L5 spectrum analyzer.
About the 7L5, it is 2 "slots" and would require support for "horizontal" signal. Any plan for that?
Also, does your PCB support read-out?
I've also a 7000 extender project but only for repair/calibration purpose.
Your is much more elaborate, I'd be delighted if I can use my 7L5 "standalone".

Best regards,


 

HI Yang,
WOW What a great idea! Congratulations on coming up with a wonderful project that will let everyone take advantage of some great Tek plugins.
At least at first, to prove your concept is sound, pick the 7A22 to interface to. It has the lowest bandwidth and should be the least challenging.
I think your only challenge will be with the 7A13 because the bandwidth is 110MHz which requires a high speed buffered output to the modern digital scope.
If you succeed with these initial four plugins many more will become possible as well.
I assume there is no plan to include the on-screen readout but without it this is still a great idea.
For a future version I would like to suggest merging two boards together so they can share one power connector for the dual width 7S14 and 7S12.

Dennis Tillman W7PF
TekScopes Moderator


Ed Breya
 

Unfortunately, it's not as simple as just providing power and an output interface. A lot of EMC cleanup will likely be needed for these desirable plug-ins to attain their normal performance. The main issues will be SMPS noise on the local supplies and even worse, the common-mode and ground currents that tend to spew forth and go all over the place. I'd suggest prototyping up a rig with the 7A22 first, then hook it all up in a realistic measurement situation and see what comes out.

I'd think the most susceptible to problems will be 7A22, 7A13, and 7L5, with their high sensitivity, and the likely noise frequencies being right where they like to work. The higher SAs like 7L12 and up, and the samplers like 7S14, are likely much less problematic, especially if you can live with a little spurious content at the lower frequencies. Without knowing any more detail, one thing I'd suggest is to have provision to remove the corner screws from the plug-in back, and add metal spacers and screws to bond the board ground plane with the frame. I see there are holes at the board corners, so maybe this is already in the plan.

What I can picture as an immediate use as-is, with no concern for EMC, is in servicing plug-ins on the bench, fixing the usual Ta problems and such, where you just need to get it alive again. Imagine just sticking a little box on the back of the plug-in (or two or three on the big ones), fed by a little cord from a brick, instead of the usual extender rigging always in the way and ready to fall off. This of course doesn't make it fully operate, but I think it would address most problems, which are power related, at least in my experience.

I'm still curious about what edge connector is used. I don't recall ever hearing if there's a standard off-shelf type that would work. Does anyone know?

Ed


Ed Breya
 

Oops - I think I just realized the answer to my edge connector question must be yes, since people have been building 7K extenders for some time. I have some original Tek ones, so never needed to look at these others.

Ed


nonIonizing EMF
 

On Thu, May 7, 2020 at 05:51 PM, Ed Breya wrote:


Oops - I think I just realized the answer to my edge connector question must
be yes, since people have been building 7K extenders for some time. I have
some original Tek ones, so never needed to look at these others.
Yep, I had a moment where I was wondering with the Tektronix D14 design (?) and started reading into more regarding anticipation if I might need for the 5000 and 7000 series mainframes. Wound up updating the JAMA Wiki last winter or so also to have a reference since isn't something I do often and better to make public not just for my memory. https://en.wikipedia.org/wiki/Japan_Amusement_Machine_and_Marketing_Association#Other_Origins

I still haven't read into the TDS-8000's connectors and pinouts... yet.

I am working on a project that generating all the necessary power for a 7000 plugins, so that you can use some 7000 plugins on modern digital oscilloscope.
Seems interesting... though I haven't even DQ'd & IQ'd my 7904 yet. ;-|) Just got the motivation to make another farm building though... with a bunch of stuff and am working on the layout to include my Tektronix gear not only rackmounted. I need some bench space and shelving, my other ones are getting messy.


 

Hi Yang,

I think that you have a great idea of using the refined functionality of 7000 series plugins so that they benefit from unique features of a digital scope, like the ability to store nearly unlimited waveforms and do all sorts of computations on them.

The most natural and complete interface to a 7000 series plugin is a 7000 series oscilloscope. I assume that where there are 7000 plugins, there must be a 7000 scope nearby. I also imagine that most if not all of these scopes have outputs that are the vertical signal and the gate of the time base being used.

I did a little experiment, using two channels on a 7A26 vertical unit plugged into my 7704 scope. I connected the VERT SIG output on the 7704 to a single channel of my 547 scope. then I connected the +GATE signal of the 7704 to the external trigger of the 547, and... voila! After a few adjustments I could see the two channels alternating on the 7704 exactly replicated on the 547. (I like more the trace on the old 547, so maybe should I leave the two scopes like that?)

A sweep change on the 7704 had to be matched by a sweep change on the 547, otherwise one could see strange things, but this was the only adjustment necessary. The vertical gain in the 547 only needed to be adjusted once to match the 7704, and then any changes in the 7A26 plugin, even changing from alternate to single channel, were followed by the other scope.

Could this be a way to implement your original idea without having to build any additional hardware?

Regards,
Ernesto


 

On Thu, May 7, 2020 at 05:45 PM, Yang Cui wrote:


I am working on a project that generating all the necessary power for a 7000
plugins, so that you can use some 7000 plugins on modern digital oscilloscope.
For this, it may be worthwhile to have a look at the 7704A. This model consists of a lower acquisition module and an upper display module with a single plugged connector in between: after unplugging the connector, the upper module may be lifted off completely.
The lower unit contains the power supply and interface circuits, including the channel switches.

Tek developed the P7001 digitizer/processor/memory to put in between both, resulting in an early analog 'scope with digital storage, see <https://w140.com/tekwiki/wiki/P7001>.

In fact, some years ago I've played with the idea of building a digitizing and LCD-display top module for a 7704A acquisition unit. I didn't have a 7704A at the time and the idea of cannibalizing one quickly killed my plan. But the idea of having one complete mating connector (to be taken from the display module) was very appealing.
The 7904A, 7854 and 7104 have a similar construction but don't have the complete modularity with just the one connector.

Raymond

Raymond


ycui7
 

Thanks All for the response.

The current status is:

1. The DC DC converter can only put out 10W at the moment and the controller chip overheat, the requirement is 16.5W. This partly due to the limitation of off-the-shelf transformer.
2. TI's official footprint for the differential to single-ended conversion amplifier is wrong, the part cannot be soldered, thus bandwidth testing has to wait.

A new revision is being made and waiting for delivery. The new revision uses bigger magnetics and discrete low Rdson transistors to reduce heat generation.

The DC DC conversion is isolated push-pull topology running at 1 MHz. I do not know what the noise performance will be, but they are marketed as low noise topology in linear tech's datasheet.

The bandwidth is not a major concern. TI has quite a portfolio of very high speed opamps. They perform pretty well in the past for me.

For dual slots plugins, my plan is to take two boards and you connect the output to you digital scope by X-Y mode.

If the project can get good traction, I can make a dual slot version to better serve the community. The dual slot version will be a single pcb with an even bigger DC DC converter (33W). Considering the dual slot audience is low speed output signal for both sampling and spectrum analyzer plugins, I could even include ADC and PC data acquisition, such that the addon board will be fully standalone. Of course, once I put fpga and adc on the board, it make sense to get the readout included. But that would be quite down the road. (I do have a existing board design that capable to readout >16bit signal at 2MS/s with working FPGA firmware).


 

Raymond,

The 7704A is really an interesting instrument where the two halves are interconnected by a single edge connector with a couple of coax connectors attached. I also played with the idea of running it with the two halves separated, but I don't think the length of the connector will allow for much separation. I speculated with the idea of doing it if I ever have to debug the main board connecting to the plugins and the small vertical and horizontal interface boards.

The P7001 is an intelligent ad-on, well suited for the era of the beginning 70s, when digitizing was done before the advent of fast flash converters. Today, with 12-bit converters running at tens of giga-samples/sec, that technology is a little old.

I like the aesthetics of my 7704A as it stands today, I hate to see it extended with some box sandwiched between its two halves. And it works so well now! The vertical out and sweep gate outputs preserve most of the internal bandwidth. So what better way to digitize the signals than send them to a small inexpensive digital scope?

If I had the need to digitize the output of a spectrum analyzer like the 7L13, I would buy the little Siglent Technologies SDS1202X-E 200 mhz Digital Oscilloscope that Amazon is trying so hard to sell me for $359 plus tax. I place it besides the bigger 7704A, and interconnect the two with two coax cables. This digital scope has a 200 Mhz bandwidth, a huge overkill for the logic analizer output, but well matched with the 200 Mhz of the 7704A. So with a slow sweep and 1 Ghz samples, it can get good x-axis resolution. The vertical resolution of 8 bits is a little cheap though. (but I don't know the equivalent digital resolution of the 7704 CRT screen).

I think that old and new technologies can coexist very nicely.

Ernesto


ycui7
 

Hi Ernesto,

I have multiple 7000 series scopes. My 7613, 7633 scopes have a 10-20 mV low frequency noise on the vert signal output, I could not figure out why and give up on the idea sending vertical output to digital scope for recording. The 10-20 mV low frequency noise kills the noise floor of my measurement.

My 7834 does not have that problem, but it dead a week ago. So, now I have no way to send my 7000 series plugins collection's signal to digital scope anymore. Over the time, I find it is just so much pain and effort to maintain these old scopes, so that I can get good noise performance. That is partially why I started this project.


 

On Fri, May 8, 2020 at 08:24 AM, Yang Cui wrote:


Over the time, I find it is just so much pain and effort to maintain these old
scopes, so that I can get good noise performance. That is partially why I
started this project.
Using the acquisition part of a 7704A, as I mentioned in an earlier message, of course is out of the question as a general solution. That's why I like your idea and project.
I have a few Tek-7000 backplanes with their connectors in good condition and others (in the group) may as well, so in case you'd consider allowing for the original backplane connectors as an option on your PCB layout, I'd be all for it... I've unsoldered a number of them, not a big deal - with the right equipment.

Did I mention I'm interested in purchasing a few of your "add-on boards"? Put me on your list for two single units and one double...

Raymond


 

On Fri, May 8, 2020 at 07:18 AM, Ernesto wrote:


I like the aesthetics of my 7704A as it stands today, I hate to see it
extended with some box sandwiched between its two halves.
The P7001-equipped 7704A does indeed stand out (pun intended) and looks strange in the beginning but it grows on you, especially in the vicinity of standard-height 7000's.
Of course, speed and intelligence are very limited but nice things are possible when connecting it to an external computer. Mine has the GP-IB interface.

Raymond


Michael W. Lynch
 

Yang,

This is a very interesting project. I hope you can work out the minor details. Thank you for your efforts.

--
Michael Lynch
Dardanelle, Arkansas


 

On a second thought, I have another choice in merging the 7000 plugins with the capabilities of a digital scope.

I plan to keep my 547, 7704A and Ernesto101 scopes for the rest of my life, regardless of the expected advances in technology. The only case they now fall short is if I want to capture a waveform for further analysis or display, like to send pictures of them to my grandchildren (if they are interested in electronics) or if I need to write a paper for an electronics journal or give a class on the subject.

Now on a second thought, I would buy the OWON XDS2102A 100MHz 12 bits High Resolution ADC Digital Oscilloscope 12bit ADC decode XDS2102A scope, $399 + tax at Amazon. Twelve bits is already a decent vertical resolution that would not degrade the image quality of a CRT oscilloscope. And 100 MHz bandwidth is PLENTY for my modest uses. I have found out that the VERT SIG output of the 7704A has only 80 Mhz bandwidth anyway. I have no idea of the quality of "OWON" scopes, probably good enough for a retired hobbyist, and I have not bought it yet so I have time to inquire. (Maybe in 20 years I will be able to buy a fancy Tektronix digital on ebay for that same money, haha).

So with two lab oscilloscopes (the 547 and the 7704A) able to connect to an inexpensive digital scope I will have all the visual needs covered. No cameras, no storage CRTs, no digitizing plugins, etc.

Ernesto


nonIonizing EMF
 

On Thu, May 7, 2020 at 08:45 AM, Yang Cui wrote:


I am working on a project that generating all the necessary power for a 7000
plugins, so that you can use some 7000 plugins on modern digital oscilloscope.
Since somewhat related, I'll note a reference here from this EEVBlog "the 'best' tektronics 7000 series plugin scope" message thread and later comments regarding the Oregon Analog Tools ASM7 ( http://w140.com/tekwiki/wiki/Oregon_Analog_Tools_ASM7 ) and even better since a schematic is included, the NT-7000 ( http://w140.com/tekwiki/wiki/NT-7000 ):
https://www.eevblog.com/forum/testgear/the-best-tektronics-7000-series-plugin-scope/msg2558799/#msg2558799


 

Hi nonionizing,

it is notable the effort to interface the 7000 plugins by the ASM7 and NT-7000.
But I see only one advantage over the natural use of a 7000 oscilloscope: physical size.
I may be biased in this opinion, since I live in Houston Texas where space is in ample supply.
And conversely, there are many advantages in having a fully functional 7000 scope at the bench, on a convenient model 3 cart, with a small digital scope used occasionally when the need arises.

If given the choice, I would rather go with Yang Cui's interface, if it will be something small that one plugs onto the tool module, rather than an ASM7, NT-7000 where one has to place the plugin inside having the same or worse limited access for troubleshooting than in a 7000 scope.

Ernesto


boid_twitty
 

I'd advise against the choice of the Owon.

My experience with SDS8102v and SDS8202v has not been encouraging.
The vendor I purchased from has had so much trouble from customers
that they stopped distributing the brand.

Issues with firmware are legion, but simply trying to get the digital pots
to behave, or coax the gui into providing cursors while performing any
other kind of work will give any user serious regrets.

I was only interested in long record and battery operation. What's the use of a long record if the center display jumps all over the place when you try to move up or down the time of plot? What's the use of a battery-operated device if at low battery, it can't turn itself off without completely wiping the firmware? ( that's right - after hiccuping continuously at low battery power down, will not boot up again.).

Could have been an amazing product and maybe the newer models are, but don't count on it untill you hear good things from end users.

The company's 'discussion forum' is no more.

RL