Talk:Oscilloscope

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[edit] Praise

Wow! Great article! Though what's the reference material you guys used? I'd like to submit this to WP:FAC. - Ta bu shi da yu 00:39, 20 Dec 2004 (UTC)

Thanks for your kind words! For the small contributions that I made (primarily having to do with analog storage), I wrote from my own knowledge. My early education came from an excellent series of technical books that Tektronix wrote describing the design of various oscilloscope subsystems, and after that, years of experience using and maintaining (primarily Tek) oscilloscopes.

Atlant 01:12, 20 Dec 2004 (UTC)

You definitely should submit it. I'd been thinking about doing the same thing myself, until I realized I'd better check the talk page first. Dinferno 12:35, 28 May 2007 (UTC)

[edit] Aquadag

The electrons, after hitting the screen, must come back to the anode so that the circuit is closed. Otherwise, the negative charge accumulated no the screen will repel the electron beam, preventing it from reaching the screen. The return path of the electrons is provdied by coating the sidewalls of the CRT with carbon particles, referred to as aquadag and by connecting this coating to the accelerating anode. --Krishnavedala 10:57, May 15, 2005 (UTC)

Well, that and the aluminized screen. ;-)
Atlant 17:05, 15 May 2005 (UTC)

[edit] Cheap 'scopes?

Does anyone have any suggestions as to where a poor hobbyist such as myself might be able to buy an oscilloscope for relatively cheap?

The standard answer used to be Heathkit (or for some, Eico kits), but that option is gone now. :-( That leaves you with the used market, and you can get pretty good 'scopes at reasonable prices if you look hard enough. For example, companies going out of business may sell off their test equipment; that's where my '465B comes from. Another one of my scopes is an older HP military-surplus job that came, believe it or don't, for free from an annual public auction that my town holds to get rid of surplus equipment (from the schools, etc.). Nobody else wanted it so I got it for nothing at the end of the auction.
And, of course, it depends on what you mean by "relatively cheap"; a '2465 still costs a big chunk of change. And at this point, while you can probably get an old vacuum tube cheap, I'd imagine it would pretty hard to keep it up-and-running if you use it often.
Atlant 23:32, 17 October 2005 (UTC)
Well I would suggest Ebay nowadays. Or if you are near to any amateur (ham) radio rallies/auctions, these seem to be places where things go for a song esp if you know what youre looking at/for and maybe can do some minor repairs.--Light current 23:41, 21 April 2006 (UTC).
You can download a free PC oscilloscope for Windows here.--Max 10:03, 23 June 2006 (UTC)
There is another free PC one here --Trounce 14:13, 4 November 2006 (UTC)
Most real work needs more bandwidth than a sound card can deliver, though.
Atlant 11:33, 23 June 2006 (UTC)

[edit] Washing your oscilloscope

This is not as crazy as it first appears. As long as the components dont suffer from water or mild detergent damage, this is a good way of removing dust and unremoved flux, nicotine(!) etc that can compromise the circuit boards surface high resistance and crap build up on switches. After washing, its important to let the boards dry out thoroughly, and I recommend placing them near the output of a dehumidifier for about 24 hrs before putting them back and applying volts. I have done this procedure on the plug in boards from a TV set and the set worked perfectly afterwards!--Light current 22:09, 21 April 2006 (UTC)

How do you wash it? Manually in a sink? dishwasher? — Omegatron 23:25, 21 April 2006 (UTC)

No, no of course not a dishwasher. Be serious! You take out all the little pcbs, run them under warm water with some washup detergent using a soft bristled brush to clean away all the muck. If you're sure all parts will stand it, you could use Isopropyl alcohol initially to get rid of greasy/oily/flux/nicotine deposits. Then you rinse thoroughly in clean warm/cold water and let them drip dry before putting them near the dehumidifier for 24 hrs. --Light current 23:33, 21 April 2006 (UTC)

I didnt remove part of your comment intentionally (could have been a mistake)- I thought you had! I must have done ctrlX insted of ctrlC Sorry about that!--Light current 20:52, 22 April 2006 (UTC)

Oh, ok. Running PCBs through a dishwasher is pretty common to remove flux, etc. — Omegatron 20:58, 22 April 2006 (UTC)

Id not heard that one. What solvent do you use to get rid of flux? Maybe a dishwasher is good- but I dont know enough about them to be sure--Light current 21:00, 22 April 2006 (UTC)

You use water-soluble flux, of course!  :-) — Omegatron 18:12, 31 July 2006 (UTC)

[edit] Alternatives

rm from page:

[edit] Alternatives to the oscilloscope

There is an affordable alternative to an oscilloscope that is useful for many tasks, and perhaps superior for radio repair, and that is to listen to the signals.

The basic plan is to mix (multiply) an intermediate frequency with the signal, and then amplify and listen to the result through a speaker. In other words, you are using amplitude modulation to shift the signal down into the audio band. (For audio frequency signals no modulation is necessary, of course.)

With modern solid-state circuits, such equipment is cheap and can run from a small battery. This diagnostic system was widely used for almost all early radio development, and is still used in Asia, and by impoverished amateur radio operators. In the Soviet Union, the standard radio diagnostic tester combined a multimeter with an oscillator, frequency mixer and audio amplifier that could perform this task.

Or to put it the other way around: An single scope replaces a network analyzer, frequency mixer, delay generator, gated integrator, frequency counter, boxcar avarager

This matl is nothing to do with oscilloscopes but testing methods in general.--Light current 07:27, 28 April 2006 (UTC)

[edit] Tek scope caption

This really is too long Atlant. It unbalances the page and the photo. 8-( Maybe most of this info could go in the body of the article?--Light current 04:52, 31 July 2006 (UTC)

It probably should go in whatever section is describing the various function blocks, maybe with some circles and arrows Photoshopped in. If need be, I could certainly shoot some photos of other oscilloscopes (although the odds are they'd be Tek :-), 'cause that's what most of the 'scopes I have access to are! ).
Atlant 13:01, 31 July 2006 (UTC)

Are you suggesting close ups of the various functional areas on the front panel with a small caption describing each one? If so, I think thats a good idea 8-) It doesnt matter that they'll all be Teks. They're probably the best examples to use anyway and my favorite! --Light current 15:25, 31 July 2006 (UTC)

Or a single image with circled areas and call-out lines leading to captions such as "Vertical controls" and "Time base controls", etc.
Atlant 15:54, 31 July 2006 (UTC)

If you like although that sounds like a lot more work to me! And I wouldnt know how to do it 8-|--Light current 16:37, 31 July 2006 (UTC)

I agree that graphics of many different types of controls and explanation of what each does would be great. — Omegatron 18:13, 31 July 2006 (UTC)

Would graphics be better than close up photos of real scopes? 8-|--Light current 18:26, 31 July 2006 (UTC)

Speaking just for myself, I'd prefer the concrete example of the front panel of a real 'scope, suitably disected and labeled. I'll try to cook something up.
Atlant 19:15, 31 July 2006 (UTC)
Agree that real scopes are better. — Omegatron 19:38, 31 July 2006 (UTC)
I've now got a fairly-good photo of a current Tek DPO7254 (2.5GHz Digital Phosphor Oscilloscope) that I'm trying to ready for the article. It would probably mae a better subject for an "expanded" photo, allowing us to have a smaller photo as part of the article's lede. But if the DPO photo doesn't work out, I'll pose and shoot my good-old 465.
Atlant 15:58, 21 August 2006 (UTC)

I have temproarily restored the pic to the large size pending new photos.--Light current 16:01, 21 August 2006 (UTC)

I have made what I hope is a compromise. You can have your huge picture, but not at the top of the article where it squeezes out the text, and where the reader won't understand the caption because the terms haven't been explained yet. The huge picture with the huge caption belongs lower down, where it can be explained in depth. I'm sorry about the two copies of the same photo, but that can easily be fixed. --Heron 20:46, 21 August 2006 (UTC)

Sorry Heron it was not I who placed the picture thus!--Light current 00:01, 22 August 2006 (UTC)

[edit] Bandwidth record

The article currently contains the following text:

The current bandwidth record, as of February 2005, is held by the Tektronix TDS6000C oscilloscope family with a digitally enhanced bandwidth of up to 15 GHz and costing about US$150,000.

But Tektronix currently sells a 'scope (the TDS8200 family) which has a sampling bandwidth ranging up to 70 GHz (and it's possible other vendors may go faster; I haven't looked). So shouldn't this sentence be modified to state something like "real time bandwidth" or "non-sampling bandwidth"? (FYI: That TDS6154 manages 40 GS/s across two channels!) And as of 2006, is this Tek still the fastest?

Atlant 22:46, 31 July 2006 (UTC)

[edit] Scope picture

C'mon 'O', how many people know how to select the proper thumb size?--Light current 23:59, 21 August 2006 (UTC)

[edit] Merge from Dual beam oscilloscope

I don't see any need to have a separate article for dual beam oscilloscope, and as the existing article dual beam oscilloscope is quite short, it would make good sense to implement the proposed merge. DFH 19:18, 26 September 2006 (UTC)

Agree merge--Light current 10:48, 21 November 2006 (UTC)
Thanks for agreement. Merge now done. DFH 19:22, 21 November 2006 (UTC)

[edit] Curve tracers

I had intended to create an article about curve tracers, but as yet, I have been too busy. If anyone else would like to take up this task, I would be only too pleased. DFH 19:41, 21 November 2006 (UTC)

I've substantially expanded an existing article. See Semiconductor curve tracer. Feel free to take it farther; it certainly needs the addition of a modern-day picture (which I'll shoot if I get a chance, but feel free to beat me to it).
Atlant 00:54, 28 November 2006 (UTC)
Why are curve tracers so damn expensive cf ordinary scopes?--Light current 00:59, 28 November 2006 (UTC)
Curve tracers are substantially more complex (consisting of an oscilloscope plus a bunch of high-capability, automated power supplies and miscellaneous measuring gear) and they have a much more limited marketplace, limiting the potential volumes and the resulting economies of scale. There's probably also an element of "what the market will bear". I was looking at our Sony/Tektronix curve tracer the other day and noticed it had a CRT with a custom "internal graticule" and I wondered what that custom CRT alone must have cost Tek.
Atlant 01:10, 28 November 2006 (UTC)
Well Atlant Im sure you or I could quite easily design ramping voltage and current sources as a small add on for a normal scope. In fact Im sure Ive seen home brew projects published to do it. After that you only needa low BW scope. So I tend to go with your latter reasons instead of the former!

BTW are you sure about this piece of the article?>

The main terminal voltage can often be swept up to several thousand volts with load currents of tens of amps available at lower voltages.

8-)--Light current 01:15, 28 November 2006 (UTC)

I'm sure about the "several thousands of volts"; that same Tek/Sony curve tracer can do 2,000 volts! I'll verify the current claim.
Ahh. here we are: 10 amps on the particular model I was thinking about.[1]
Atlant 02:04, 28 November 2006 (UTC)
OK. Its just that I dont remember the old Tek 575 tracer going very high in volts or current. But its been a long time since Ive seen one! If you look at the photo on the page, youll see that the volts/div goes upto 20, giving about 200v max, and the current per div goes up to 1000mA/div ginig 10 A max. But perhaps theres a multiplier that is brought in somewhere?--Light current 02:07, 28 November 2006 (UTC)
And if you really want to cook, howzabout 400 Amps pulsed power and 3KV? [2]
Atlant 02:12, 28 November 2006 (UTC)
Yeah certainly looks like a cooker. Good for cooking eggs & ham!--Light current 02:14, 28 November 2006 (UTC)

I really should have explained that I was talking about the S/H market really. Tracers like the 575 are very expensive for what5 they are I feel. Anyway Im not likely to need to use one, so no problem.--Light current 02:18, 28 November 2006 (UTC)

The 400A and 3kV are not simultaneously applied. These are different ranges. DFH 18:58, 28 November 2006 (UTC)

[edit] This ap note might aid the MSO segment of the entry

This Agilent Technologies ap note might be a useful addition to the Mixed-Signal-Oscilloscope section. It contains a vendor-neutral description of what an MSO is, and describes how an MSO can be used to debug an 8-bit microcontroller with I2C bus.

1bigdork 22:28, 27 November 2006 (UTC)

[edit] faster than the speed of light????

"By the late 1970s, with transistor components rather than vacuum tubes, Tektronix was selling oscilloscopes on which the signal trace traveled across the screen faster than the speed of light."

I mean, Tektronix built great stuff, but defying the laws of physics? I am not editing because I think this might be a malformation, so wanted to ask first...--Cerejota 16:00, 4 December 2006 (UTC)

It's a true claim. It's also a sort of inside joke. When the electron beam sweeps across the screen, there's no physical object that's actually (physically) moving very fast. The electrons are the only thing that's physically moving, travelling at their relatively-leisurely velocity from cathode to screen, with each impinging electron producing a little flash of light. And, of course, the beam is sweeping, with the trajectory of the electrons being varied with time.
It's only that trajectory that, at the screen, moves faster than light. And it's not a physical entity, so it's not constrained by the Speed of Light.
Think of a water hose and nozzle. As you sweep it from side to side, the place that gets wet can move very fast, much faster than the water droplets themselves are moving. It's the same thing here. Or, if you like, think of you aiming a laser pointer at an astronomical screen a few thousand kilometres away; the spot you create on that screen can move much faster than the speed of light.
Your average 'scope screen is 10 cm (0.1 M) across in the X dimension. Light travels at 300,000,000,000 metres per second so about 3.3 ns per metre so about 33 ps per cm. If the aggregate effect of the horizontal sweep and the vertical deflection is moving the illuminated spot on the screen faster than that, the spot is "moving" faster than light. And the fastest calibrated sweep speed of the Tek 7104 'scope was 200 ps/cm, so with some vertical deflection added in...
Atlant 16:15, 4 December 2006 (UTC)
  1. No sir ! The laser beam would bend. The coherent light of a laser beam isn't low velocity water droplets. If one sweeps the beam towards a "screen a few thousand kilometres away" the laser beam cannot accelerate beyond the speed of light, it will just take more time to reach the "screen".58.166.39.216 05:25, 8 March 2007 (UTC)

[edit] advanced features of oscilloscope

hi if somebody could help me out on this .... this is my library research project... my email id is: mohit AT rome DOT com.ill be highly obliged. thank you

well, I'm afraid the very object of school research work is to get you to do the research work... CyrilB 21:57, 19 February 2007 (UTC)

[edit] Links to circuits

I think there are not enough links to circuits used in the scope. Delays, ramps, variable amplifiers, samplers, triggers. Or do I just miss them, I think I have seen ADC at least? Arnero 13:51, 13 March 2007 (UTC)

[edit] makers

I guess their are not too many old timers arround.

I started trying to find makers and noted that many of the test equiment firms Don't have a Wikipedia presence. Other brands that come to mind is B&K Dynascan, (and the B&K Televison anayist should be decribed also :) (Perhaps as part of Flying spot scanner )) PACO, Hicock, .... cmacd 14:39, 5 June 2007 (UTC)

[edit] Digital scope inventor?

This article claims:

"The first Digital Storage Oscilloscopes (DSO) was invented by Walter LeCroy (who founded the LeCroy Corporation, based in New York,"

However - the earliest references to a Lecroy Digital Oscillscope seem to be 1985. See: https://www.fundinguniverse.com/company-histories/LeCroy-Corporation-Company-History.html http://www.hmi.de/events/SEI/archiv/2003-03/vortrag/wiegard_lecroy.pdf

The earliest complete combination analog/digital oscillscope was the 1980A/B. It is detailed in the Sept. 1982 issue of the Hewlett Packard Journal. http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1982-09.pdf

It seems incorrect to claim the Walter LeCroy invented the digital oscilloscope.

192.25.240.225 00:11, 13 September 2007 (UTC)MikeB

I concur that this is incorrect. Hiro Moriyasu of Tektronix should be credited with this invention.

The same paragraph credits LeCroy with having the highest-bandwidth digital scope. This is misleading, because this refers to a sampling scope. Sampling scopes lack the triggering, single-shot, and real-time signal viewing required by most engineers to be a true DSO. In the real-time scope world, Tektronix holds the nominal bandwidth title at 20 GHz, but this claim is disputed by both LeCroy and Agilent because they cannot verify that a 20GHZ sine wave is attenuated less than 3dB. The LeCroy and Tektronix scopes probably have comparable max BW @ 18GHz. Note: I do not work for either of these companies. -- 1bigdork —Preceding unsigned comment added by 1bigdork (talk • contribs) 03:33, 17 January 2008 (UTC)

[edit] True or false information in this edit?

I found this edit from an IP today, "Lissajous figures are an example of how an oscilloscope can be used to track phase differences between multiple input signals." is that edit really incorrect?, or is it just misstaken for a vandalism? Please motivate why false/true. —Preceding unsigned comment added by Electron9 (talk • contribs) 21:39, 14 November 2007 (UTC)

This was the existing text. The anon IP swapped it from some different text; I replaced it. It is correct. Oli Filth(talk) 22:21, 14 November 2007 (UTC)

Yes - lissajous do measure the phase between two signals. The scope should be in XY mode, and the signals should be of the exact same frequency (normally originating from the same source). If the phase difference is zero, the two signals are identical and x=y, which is the equation of a line, which is exactly what is displayed on the scope. If phase difference in 90 deg, a circle is formed, and if phase difference is 180 degrees, x = -y and a line of negative slope is displayed. See Lissajous[3]. 71.214.54.167 (talk) 02:46, 15 December 2007 (UTC)MikeB