How important is having an analog oscilloscope with time delay? - Page 1
Forum section: electronics / testgear

author: mstettle
author_rank: Newbie
timestamp: October 27, 2017, 03:41:03 pm
content: Hi folks,I have a Tektronix 2225 and a Rigol 1054z scope. The 2225 does not have time delay capability. My question to the experts out there is do I need an analog scope with time delay--is this a must have for serious repair work?Thank you,Mark

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 03:53:30 pm
content: You don't need an analogue scope with a delayed timebase if you have a DS1054Z as you can scroll back and forward in time from the trigger point on the DS1054Z which is functionally more advanced.If you were stuck on a desert island with a 2225, you can still get by though as the 10x magnification and horizontal position usually has a reasonable amount of resolution.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 27, 2017, 03:54:48 pm
content: There is not much need for the time delay. It's one of those functions one rarely uses. It can help some times, but then the DSO might be a good option too. Also just using X magnification can be an alternative as well (maybe a little less accurate). With analog scopes the delay is usually analog too, so not super precise either.One may not need a analog scope at all, if you have a good DSO.

author: tggzzz
author_rank: Super Contributor
timestamp: October 27, 2017, 03:58:10 pm
content: It is very helpful to have a delayed timebase.It is not absolutely essential since sometimes you simply don't need it, and when you do you can often work around the lack - but that frequently needs forethought and extra work.In a digitising scope, the analogous problem is a short acquisition memory.

author: mstettle
author_rank: Newbie
timestamp: October 27, 2017, 04:37:11 pm
content: All, thank you so much for the great info!

author: nctnico
author_rank: Super Contributor
timestamp: October 27, 2017, 05:00:09 pm
content: Quote from: tggzzz on October 27, 2017, 03:58:10 pmNo, because you have pre/post trigger.I wouldn't invest in any analog scope.

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 05:08:15 pm
content: I wouldn’t in a professional environment but they’re fine for home use. Especially when you’re cash constrained.

author: David Hess
author_rank: Super Contributor
timestamp: October 27, 2017, 08:12:21 pm
content: The x5/x10/x50 alternate magnification function which the 2225 supports will cover most applications that a single (1) or dual delayed timebase would be used for. The exceptions include things like selecting a specific video line to display.For example, I often use a delayed timebase to view the reverse recovery waveform of a diode with high detail. The alternate magnification function of the 2225 or the zoom capability of a DSO like a Rigol DS1054Z which also lacks delay capability would be almost as good.(1) The x5/x10/x50 alternate magnification capability of the 2225 might be regarded as a less expensive alternative to the single (!) delayed timebase capability of the Tektronix 2213/2213A which preceded and was effectively replaced by the 2225.

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 08:25:15 pm
content: Interesting as you can pick up a 2225 for virtually nothing.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 27, 2017, 08:25:31 pm
content: Its the old analogue vs digital debate again. If you are dealing with repetitive waveforms analogue is fine, but if its a single event then storage = > digital is king.I remember a few years back when I first got my hands on a Tek465B. I was looking at a PAL video signal, you could trigger on the frame sync and look at individual lines using delay. You could even see the teletext info on individual lines.If you are looking for another analogue scope and have the choice, delay is handy. You don’t have to use it, but chances are its a quality instrument if it has it..It would be interesting to compare the Rigol 1054z and a Tek 2465B.Ken

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 08:44:47 pm
content: I’ve got a 465b and a ds1054z and the ds1054z is my go to scope if I’m honest. I like to play with the analogue scope but the ds1054z does the business.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 27, 2017, 08:50:23 pm
content: Yes the advantage of modern scopes is they don't stick out the back for 2ft !. And you can fit them in a suitcase if you are travelling.But they don't keep the lab as warm.Ken

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 09:00:29 pm
content: Very true. My bench is tiny so the analogue scopes live elsewhere. The 465B is currently in bits on the living room table while I clean the attenuator contacts.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 27, 2017, 09:20:22 pm
content: At the risk of diversifying the thread, its funny you should say that about the 465B attenuator, I also have a sick one, CH2 is fine, but CH1 intermittent and some gain settings don't work. I'm not looking forward to stripping it down.Ken

author: David Hess
author_rank: Super Contributor
timestamp: October 27, 2017, 09:41:33 pm
content: One of my complaints about the form factor and weight of modern oscilloscopes is that it takes two hands to attach cables and probes to prevent the instrument from being pushed around. In some cases, it takes two hands to operate controls like buttons placed toward the top of the instrument least it be pushed over or back.If the old oscilloscope has a large bail, then it can be used to recover the desk space it would otherwise take. Better of course is to put it on a shelf or cart.On the other hand, I sure would not want to take any of my CRT oscilloscopes traveling with me except by automobile. The weight would not bother me so much but they are not as rugged.On the subject of the utility of dual delayed sweep which is what most people think of since single delayed sweep is very rare, it allows triggering after delay which is a feature I miss on most DSOs these days. An analog oscilloscope using this provides a real time display of the delayed signal which is either shows jitter or if the triggering after delay is used, no jitter. DSOs without delayed triggering which are common now cannot do the later and under some circumstances cannot do the former depending on their record length.My go-to oscilloscope is a 2232 though so I get analog dual delayed sweep *and* digital storage with dual delayed sweep. Its large bail can be used to recover most of the bench space it would otherwise take and it is heavy enough that no manipulation of the controls will push it around. I could do without the analog capability if a DSO provided a good display.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 27, 2017, 11:48:59 pm
content: Quote from: David Hess on October 27, 2017, 09:41:33 pmMaybe there is a work around, like gluing or clamping a bit of wood or aluminium angle on your bench to prevent this happening.QuoteBack in the day, we used to take 465s & the like all over the State by air, as well as by road.A small, snug, road case kept them secure.Certainly the weight never was a problem.We used to lug R & S Polyskops around---even a 7000 series Tek was a featherweight by comparison.QuoteI was put off DSOs in the early days, as the old ones were pretty useless for any serious TV work.I became so used to delayed time bases that analog 'scopes without this facility feel clunky & hard to use.My generation were spoilt, as we got to learn on our Employer's gear---we never could have afforded our own Tektronix or HP instrument.

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2017, 11:55:51 pm
content: WRT to the bench space, I don't have a particularly deep bench so if I pull the scope to the front, tip the bail over and down, I can hang cables on it therefore solving the problem of where to put your banana leads and probes. Plus the top is stable enough (apart from the damn DM44 on my 475) to pile a load of other kit on.

author: tggzzz
author_rank: Super Contributor
timestamp: October 28, 2017, 12:14:55 am
content: Quote from: David Hess on October 27, 2017, 09:41:33 pmIn the early 80s I went on a trip with a 465 to a war zone (courtesy of Colonel Quaddaffi and US citizens; strange bedfellows). It survived public transport and going in aircraft holds without any external protection.