First soviet oscilloscope C1-1 teardown

[jtu]

I noticed a few posts on the forum here about Soviet oscilloscopes C1-* series. Well, today I got my hands on the granddaddy C1-1!

Today it is too late and I will have to do the teardown later, but I could not restrain myself from turning it on, taking pictures and posting here. Sorry about my teasing behaviour. The gallery contains just  3 pics now.

I know this is not test equipment, not anymore. But this was the closest category to put it under. It is history of test equipment

[jtu]

Ok, I took it apart today. Not that there is much to take apart, I only removed it from the enclosure. Initially I thought that it has to be done from the front (there are 4 screws). But aparently not, two screws in the back keeps enclosure on, you can pull it out when unscrewed.

I can not comment actual electronic design of the scope. Here you can take a look at the schematic in case you want to dig in / comment. Specs are also available there (in Russian).

I played with it shortly. Did not figure it out completely. It works, everything is logical. The thing is I was not able to view signal with harmonics above 10kHz even thou specs claim 250kHz being the bandwidth. I was able to see sinusoidal signal up to 300+ kHz, but with significantly reduced amplitude. Need to play more.

Interestinlgy, I think the way you worked with it as instrument was first you calibrated it against internal test/control signal and then applied signal under the test in order to see it and evaluate. I would not call it measurement, too crude Scope is definitely not calibrated in the sense we understand it now.

It has been opened once before me, to change power cord. I did not see any other signs of intrusion. Fuse is dated 1968, device itself 1965. It is possible it was not used for first few years. It has been on at least 4 inventory lists according to different stickers. Last use was in Riga Technical University, I got it from the guy who works there who got it when those were going for utilisation. I did not ask for the year, but he's young guy.

I did add few more pics to the gallery.

Now about my motivation to search for exactly this scope. My own connection to this model is from mid 70ties. My parents worked in one of the insitutes of university nowadays known as University of Latvia. I myself graduated from there in 1996, but that's another story. When I was a kid ~5-6 years old my parents got rid of me by sitting me in front of this scope, turning it on, (I guess) giving me test signal and letting me catch it, loose it, catch it again and play with it Which I did for significant amounts of time. Repeatedly. I had no clue what I was doing, just turning knobs, but it totally fascinated me. This is the reason why now I was able to remember the model, it is "burned into my retinas" I browsed through Soviet scopes and this is unmistakeably the one.

Some sources (e.g. this) claim this is the first soviet scope design from 1948. The one I got says the year of production is 1965, serial #7716. But this is renamed model, so this is not one of the first 10k scopes in USSR. Still, I know people who learned scopes in 80ties and even 90ties in school using this scope. Quite long life, I'd say

[radiolistener]

it will be interest to see teardown of the first USA oscilloscope, for comparison 

[helius]

This was a very early 'scope from the 1930s, made by National:


You can see pictures of other 1930s 'scopes, more than I've seen anywhere else, here: http://www.myvintagetv.com/vintage_test_equipment.htm

[001]

In fact c1-1 is not "first"oscilloscope 
It is no more than standard code for soviet gear after WWII

[iMo]

Still working this 32 years old C1-99
Frankly, a quality construction, I have to admit.
Btw, looking for an expertise - want to adjust something in there..
PS: 50ns/div in the picture below (it can do 5ns/div).

[james_s]

That's pretty cool. Most of that old Soviet stuff has a unique look to it, very industrial. That sort of stuff is not often seen over here.

[rsjsouza]

Interestingly similar to Dumont 208 oscillograph of the 1940s.

(I had the opportunity to get one locally but for one reason or another I couldn't get to it  )

[jtu]

In fact c1-1 is not "first"oscilloscope 
It is no more than standard code for soviet gear after WWII

Could you be more specific, please?

First, I don't get your meaning about standard code.

Second, I was referring to a book where it is claimed this is first mass production scope design. Could you refer me to some more material on this?

[001]

Standard signs comes after 1953
"с" is for "oscilloscope"
"1" is for "common use"

The 1951 model was  marked as "ЭО-6" (cyrillic letters)

[jtu]

Interestingly similar to Dumont 208 oscillograph of the 1940s.

(I had the opportunity to get one locally but for one reason or another I couldn't get to it  )

That would not be surprising to me. Soviets stole all kinds of designs. There were basically no private property under that political system / in that regime, why there should intelectual property be a thing...

[jtu]

Standard signs comes after 1953
"с" is for "oscilloscope"
"1" is for "common use"

The 1951 model was  marked as "ЭО-6" (cyrillic letters)

You are correct and I know that. I was referring to first scope _design_, not designation / model. I mentioned that in my first post.

I was asking because I heard once something similar, but was not able to get more then.

Btw, I don't think this is even the first design, I think this is the first _mass produced_ design. As you say, "common use". Most probably some military or navy or aviation ones existed before this.

[rsjsouza]

Interestingly similar to Dumont 208 oscillograph of the 1940s.

(I had the opportunity to get one locally but for one reason or another I couldn't get to it  )

That would not be surprising to me. Soviets stole all kinds of designs. There were basically no private property under that political system / in that regime, why there should intelectual property be a thing...

Well, in the early 1940s Russia was actually an ally. It may have well been an exchange of technology to help with the war effort.

[jtu]

Well, in the early 1940s Russia was actually an ally. It may have well been an exchange of technology to help with the war effort.

Yes, might as well be the case. My first reaction was steeling just because I have seen one too many case of shameless copying.

[jtu]

Btw, here's pic of another early model С1-2 / 25-И.

[chris_leyson]

Thanks, nice teardown, you don't often see scopes of this vintage. Reminds me of my first scope, a Cossor 339, before the days of triggered timebases. I couldn't translate the front panel labeling for the timebase controls but I guess one of them would be the Russion equivalent of "SYNC" or Synchronisation".

Early scopes had "timebase" ranges denoted in frequency rather than time, like 2-7Hz, 7-30Hz, 30-130Hz, 130-500Hz etc and it was interesting to note that from the C1-1 schematic that the timebase oscillator uses a gas filled thyratron or triode in a two valve timebase so the maximum frequency would have been limited to around 50kHz or so due to the deionisation time. The Cossor 339 used a "hard" valve Puckle timebase circuit that worked up to 250kHz but required a third valve.

Triggered Timebases It's generally claimed that Tektronix introduced the first "triggered" timebase, designed by Howard Vollum in their first scope the TEK 511 introduced in 1947. However, Dumont might have introduced the first triggered timebase scope in 1945, the Dumont 248. An interesting paper on oscilloscope development which discusses the triggered timebase. https://www.ee.ryerson.ca/~phiscock/papers/scope-history.pdf. Maybe Howard Vollum's contribution to timebase development was the dual triode bistable "state machine". I couldn't find a copy of his undergraduate thesis "The creation of a new kind of cathode-ray oscilloscope" but it would give a good insight into the TEK 511 development.

There is an interesting EDN article "A history of oscilloscope development in Vilnius - EDN". What remains of Elektrit is now Eltesta which is a sister company of PicoScope. Eltestra design the high speed sampling scopes and PicoSope rebadge and market them.

[jtu]

it was interesting to note that from the C1-1 schematic that the timebase oscillator uses a gas filled thyratron or triode in a two valve timebase so the maximum frequency would have been limited to around 50kHz or so due to the deionisation time

Interesting. Specs claim 250kHz (or even 300kHz), but in real life I was not able to see anything but attenuated sine above 50kHz. But there should be something behind 250kHz in specs...

There is an interesting EDN article "A history of oscilloscope development in Vilnius - EDN". What remains of Elektrit is now Eltesta which is a sister company of PicoScope. Eltestra design the high speed sampling scopes and PicoSope rebadge and market them.

The book I referenced is exactly the history of scope development in Vilnius during Soviet time. It is in Russian and it contains very good comments on design history.

It also contains stories about people involved, but that part feels too Soviet-nostalgic for me to enjoy. Political and KGB control is not even mentioned. Even thou the book is dated 2012. Feels flawed because those aspects are left out and those aspects were very significant in USSR, especially in military / cold war related topics. What to do and who will do it was not talent controlled, it was only possible under strict control of the worst part of the Soviet regime.