EEVblog #1022 - Finding A $50 Oscilloscope On Ebay

[boffin]

Apparently any of us that did work 30 yrs ago -- with analog only (no storage) scopes -- weren't doing real electronics; if you are to believe a lot of people in this thread.

[Brumby]

I seem to recall doing a fair bit with just a 20Kohm/volt analog meter, a stick soldering iron with a pair of needle nosed pliers, sidecutters and a screwdriver....

Mind you, things have changed.

I didn't have a dozen microprocessor boards in a box on my shelf back then, like I have today...

[Smokey]

Apparently any of us that did work 30 yrs ago -- with analog only (no storage) scopes -- weren't doing real electronics; if you are to believe a lot of people in this thread.

I've said this all over the forum before.  Mad respect for anyone that was doing electronics back in the day.  You guys actually understood so much more stuff because you had to.  We have it easy now, partly due to cheap powerful gear like modern DSOs. 

Question.  What was the first good logic analyzer that came out? 

[Brumby]

The human brain.

[Smokey]

I said good logic analyzer.  Based on the news these days, the brain doesn't count.

[Fungus]

Apparently any of us that did work 30 yrs ago -- with analog only (no storage) scopes -- weren't doing real electronics; if you are to believe a lot of people in this thread.

a) You weren't working in a world full of digital devices so you didn't need storage nearly as much.
b) I've seen all the film camera attachments and stuff you used to use when you actually needed 'storage'.
c) I bet you'd have switched in a heartbeat if today's cheap DSOs were available.

[Brumby]

I said good logic analyzer.  Based on the news these days, the brain doesn't count.

It's only a matter of finding somewhere to plug the probes in....

[nctnico]

Apparently any of us that did work 30 yrs ago -- with analog only (no storage) scopes -- weren't doing real electronics; if you are to believe a lot of people in this thread.

I've said this all over the forum before.  Mad respect for anyone that was doing electronics back in the day.  You guys actually understood so much more stuff because you had to.  We have it easy now, partly due to cheap powerful gear like modern DSOs. 

No, it just took more time and self-build tools to measure something. I recall speaking to someone who debugged firmware using a bunch of comparators, adjustable address and LEDs on a board to capture a byte at a specific address.

Question.  What was the first good logic analyzer that came out?

It wouldn't surprise me if logic analysers have been available since the 50's or 60's. They are not that exotic.

[Fungus]

It wouldn't surprise me if logic analysers have been available since the 50's or 60's. They are not that exotic.

Weren't they built directly into the front panels of most early computers? All those flashing lights...

[b_force]

They were build with a piece of paper and a pencil 

[Tony_G]

Interesting historical view from the HP Memory project:

https://web.archive.org/web/20160304120925/http://hpmemoryproject.org/wb_pages/wall_b_page_12.htm

Using Wayback because the actual site seems to have been taken over by scammers/misconfigured/something as it kept redirecting me to those fake virus popup sites (URLs seem to be all pointing to HPMemory.org instead of HPMemoryProject.org)

TonyG

[Smokey]

Interesting historical view from the HP Memory project:
https://web.archive.org/web/20160304120925/http://hpmemoryproject.org/wb_pages/wall_b_page_12.htm
...

Sweet link.  That's pretty much what I was wondering.  That progression is pretty amazing.

[vk6zgo]

Apparently any of us that did work 30 yrs ago -- with analog only (no storage) scopes -- weren't doing real electronics; if you are to believe a lot of people in this thread.

a) You weren't working in a world full of digital devices so you didn't need storage nearly as much.
b) I've seen all the film camera attachments and stuff you used to use when you actually needed 'storage'.
c) I bet you'd have switched in a heartbeat if today's cheap DSOs were available.

 The number of times storage was really needed, I could count on the fingers of one hand.

The Polaroid camera attachments usually were used when checking waveform "specs", rather than to record some fleeting happening.
In fact, they often incorporated a "projected graticule" device which projected a transparency upon the CRT
face.
You fitted the waveform of interest into the reference marks on the image, checked its compliance, & if required,  took a picture .

Those of us who were quite "gung ho"about digital things were in for a horrible shock when the Tek & HP guys came round to demonstrate the first generations of DSOs, as they were virtually unusable for everyday Electronic work, which consisted of a combination of analog & some digital circuitry.

A lot of the stuff Techs do on a day to day basis is to do with signal integrity at a quite a basic level.

"Is the signal there at all ?

"Is it approximately the right level?"

"Is it breaking up, or will it do so if I wiggle the cable, tap the board, etc?"

"Is there a lot of hum on the signal?"

It is nice to be able to see "runt" pulses, read RMS values & all the rest, but this is of more importance to EEs developing stuff which hasn't actually worked yet, than to anyone fixing something which has worked.

Police Officers spend most of their time apprehending speeders, burglars, street drunks, & so on.
The  International Jewel Thieves don't come along very often.

[Tony_G]

Sweet link.  That's pretty much what I was wondering.  That progression is pretty amazing.

It's a good site and the admin just got back to me saying that he thinks it's corrected.

Personally, I just bought a 16902A & 16902B Logic Analyzers - I'm looking forward to get them and try them out.

TonyG

[boffin]

And for those looking for the mythical $50 scope; I offer you up this C$50 here in Vancouver on Craigslist right now

https://vancouver.craigslist.ca/bnc/ele/d/hitachi-oscilloscope/6325326081.html

[bjcuizon]

I believe someone on the forum is giving away 4 IIRC..
https://www.eevblog.com/forum/buysellwanted/free-oscilloscopes-for-beginners/

[guido]

I would like to hear your list, even a minority list, where an analog scope is better than a DSO.  Not just equivalent, or sufficient, but better.

As a prop in a TV program   Slow timebase, mucho intensity and a slow moving dot on the screen.

 

[Tony_G]

I would like to hear your list, even a minority list, where an analog scope is better than a DSO.  Not just equivalent, or sufficient, but better.

In general I agree but I did have a scenario for the list:

The reason I acquired an analog scope was for Z-Axis support. The DSOs that I tried (HP 54845A, 54622A, TDS 784D, one other which I can't remember but I borrowed from work) simply didn't display the trace correctly because the HP 8340B Sig Gen expected the Z-axis to work the way the old scopes did.

Sure it is a pretty specific scenario but it is one that I really ran into. I ended up buy a Tek 2235A to address it.

TonyG

[Smokey]

I would like to hear your list, even a minority list, where an analog scope is better than a DSO.  Not just equivalent, or sufficient, but better.

...
The DSOs that I tried (HP 54845A, 54622A, TDS 784D, one other which I can't remember but I borrowed from work)
...

I haven't worked with these scopes and I'm not making any judgements about capabilities or anything... Just point out that:
54845A = Manual publication date of 2001
54622A = Manual publication date of 2000
TDS 784D = Manual release date of 1999

That's a technological eternity. 

[Fungus]

I would like to hear your list, even a minority list, where an analog scope is better than a DSO.  Not just equivalent, or sufficient, but better.

As a prop in a TV program   Slow timebase, mucho intensity and a slow moving dot on the screen.

 

Yep. Decoration.

Decoration, heating the room, filling up large workspaces so that you look busy just by sitting in front of them.

People may go on and on about how precise they are, etc., but they're usually just comparing very expensive CROs with entry level DSOs.

Even then I'm not 100% convinced. Most of the "error" in entry DSOs would be very difficult to see if it weren't for all the measurements to two decimal places on the screen. Most "errors" in CROs are judged by eye against a graticule, so... 

[Tony_G]

I haven't worked with these scopes and I'm not making any judgements about capabilities or anything... Just point out that:
54845A = Manual publication date of 2001
54622A = Manual publication date of 2000
TDS 784D = Manual release date of 1999

That's a technological eternity.

Again, I agree but what you're seeing here is the oscilloscope version of the buggy whip - It's not that the modern scopes aren't good, it's just that no one needs the "buggy whip" so they've stopped selling it/adding it as a feature. I used those scopes because the more modern ones I had access to simply didn't even have the Z-Axis feature or they explicitly implemented it as blanking only.

If I didn't need to work on that 8340B then I would never have needed the Z-Axis feature (or at least a Z-Axis feature that was more than just simple blanking) and thus would never have needed an old analog scope.

All I'm saying is that there is one scenario where it made sense to use an analog scope and that scenario is so corner case that it doesn't detract from the underlying point that you were trying to make, which is that modern DSOs are equal to or better than their equivalent period/range analog scopes.

TonyG

[guido]

Don't get me wrong, i analog scopes a lot. Just like the way they work. I have digital scopes, but very old ones. If i need to do anything else then 'scope' business, i take some other tool instead. Like a proper logic analyser, FFT analyser or whatever. If for some reason i would need a modern digital scope, i would just buy it. I might if both my acient digital scopes would go belly up. But i have a lot of bench space and i like fixing up old equipment.

And you need to fix old scopes regularly. Source expensive compents now and then. Or they break beyond repair. It's a hobby

I also have the need for an XYZ monitor (scope). I am working on a prehistoric 7612D and that is needed to get a screen (if it would work...). Obviously don't need this digitizer at all, but it is fun to try and get it working. Not working on it often, it usually acts as storage table (it is on a crate, this thing takes the term boat anchor to the max).

On the local sell/buy site here in the Netherlands (not ebay, but ebay owned), it is sometimes possible to get analog scopes for 50 euro's or less. Allthough there are also people that think old stuff is still worth a lot more. Cannot imagine anybody buying those.

[vk6zgo]

I would like to hear your list, even a minority list, where an analog scope is better than a DSO.  Not just equivalent, or sufficient, but better.e

As a prop in a TV program   Slow timebase, mucho intensity and a slow moving dot on the screen.

 

Not much call for analog 'scopes or DSOs in TV programs nowadays--------they like a big screen with all sorts of esoteric parameters all over it CSI /NCIS style.

I remember, donkey's years ago, an episode of "Days of Our Lives", where somebody was in Intensive Care, with what was supposed to be a monitor showing their vital signs.

The Set guys had dragged an old Tek 545B in from the Technical area.

Back in the day, D.O.O.L were pretty laid back with their Set designs at any time (so many scenes look like they were done in a furniture showroom), but this was a new low, even for them.

[vk6zgo]

Don't get me wrong, i analog scopes a lot. Just like the way they work. I have digital scopes, but very old ones. If i need to do anything else then 'scope' business, i take some other tool instead. Like a proper logic analyser, FFT analyser or whatever. If for some reason i would need a modern digital scope, i would just buy it. I might if both my acient digital scopes would go belly up. But i have a lot of bench space and i like fixing up old equipment.

And you need to fix old scopes regularly. Source expensive compents now and then. Or they break beyond repair. It's a hobby

I also have the need for an XYZ monitor (scope). I am working on a prehistoric 7612D and that is needed to get a screen (if it would work...). Obviously don't need this digitizer at all, but it is fun to try and get it working. Not working on it often, it usually acts as storage table (it is on a crate, this thing takes the term boat anchor to the max).

On the local sell/buy site here in the Netherlands (not ebay, but ebay owned), it is sometimes possible to get analog scopes for 50 euro's or less. Allthough ther are also people that think old stuff is still worth a lot more. Cannot imagine anybody buying those.

As I said before, I, & others at the time, were "put off" DSOs because the early ones could not look at complex signals like PAL video at field rate, as at,say, 5ms/ div, the sample rate would fall far below the highest frequencies contained in the signal.

The first generation "bombed out"at Line rate!
This would also make it impossible to look at hum on any reasonably high,frequency signals.
I'm not sure how well the ones you have would perform.

I haven't had the opportunity to try this test with any modern 'scopes.