Getting an Analog oscilloscope

[mkpak93]

Hi all, I'm a beginner hobbyist from the usa, and I was wondering what analog oscilloscope would be good for a beginner. I've watched Dave's video where he encourages beginner hobbyist such as myself to go out an get one as oppoosed to the DSOs or whatever they're called lol. I looked through ebay and am willing to spend no more than 80 bucks. im a student and i cant invest too much :/

I have asked my EE department at my uni if they had any spare. they did but they weren't willing to give em away, idk why

As for the ebay ones, I don't really know which ones to trust and which ones not to, sometimes some say, "for parts or not working" when there's clearly a trace, and other times they say its "used but functioning" and i dont see a trace in the photos. So I was wonder if anyone out there could steer me in the right direction as to where I can find a good cheap reliable analog scope, thanks 

[c4757p]

If it's a simple instrument (usually the 50 MHz and under ones) and it's got a trace it probably works. If it has a trace then you know 1) power supplies are good, 2) horiz. sweep is good, 3) trigger is probably good, 4) vertical deflection is good (usually one side of the vertical driver fails and the trace slams to the top or bottom). There's not much else in a simple scope. More complex ones like the Tek 24x5s can have hidden problems.

Even if it has a single dot in the center, it's not really likely that both H and V will fail in such a way that the trace doesn't slam to one edge or corner. It's probably just in X-Y mode and the seller didn't know any better.

If there's anything wonky on the screen, see if you can view the controls well enough to know if it's consistent (e.g. single dot in the center when the timebase is set to 1us/div is a bad idea; a "short" trace can often mean a slow timebase combined with a fast camera).

If it has a readout, and says anything about any error of any sort, stay away unless you can find someone with experience with that particular model who can explain whether it's bad.

An angled trace or a blurry trace is usually fine, they just didn't adjust rotation/focus. In the cases where those actually go bad, it's usually just a crispy resistor.

A bent trace is bad news.

[Stonent]

Older Kenwood, Trio, and Hitachi scopes offer good value.

[c4757p]

Older Kenwood, Trio, and Hitachi scopes offer good value.

LG/GoldStar too. Simple construction, jellybean parts, and reasonably rugged.

[Stonent]

Older Kenwood, Trio, and Hitachi scopes offer good value.

LG/GoldStar too. Simple construction, jellybean parts, and reasonably rugged.

Yeah I thought about that right after I posted. 

Some older Tek scopes have special parts that are not easily obtainable.

[c4757p]

Some older Tek scopes have special parts that are not easily obtainable.

As opposed to newer Tek scopes, which are almost completely built from unobtainium.

[Stonent]

And there's always the good old Hung Chang scope:

https://www.eevblog.com/forum/testgear/my-$50-scope-seems-doa-tenma-72-720/

[Sigmoid]

I bought my scope a few months ago, and my experience is that getting a cheap and good analog one can be pretty tedious, and can take in excess of a month.
I sent two scopes I got on ebay back that had problems I wasn't equipped to handle. One was treating the trigger edge direction as a loose recommendation as opposed to a requirement... The other had an abysmal noise floor. Both looked as if they were through hell and back...
In the end, I bought a used Rigol DSO for just a little more money. As a general purpose scope, I think DSOs are a lot more versatile...

[GreyWoolfe]

Mkpak93, I don't know what country you are from, but if ham radio is popular, hamfests, radio rallies or whatever they are called in your country where amateur radio operators go to get rid of excess equipment is a source.  I saw at a recent hamfest, a Tektronix 2235 for $55USD.  I waited awhile and went back and offered $40 and it was accepted.  He said he took it because he didn't want to carry it back home.  As it turned out, all I needed to do was clean the rotary switches for the horizontal, vertical and time base and the scope went from a vertical line to visible waveforms.  If you are not in a huge hurry, you can find a deal.

[Stonent]

Back during Dave's original $50 scope video I scoured ebay for a week posting deals for other people and there were two scopes that sold for $5.50!

They were Pintek scopes that looked identical to some BK scopes I've seen before.

https://www.eevblog.com/forum/buysellwanted/fs-cheap-pintek-40mhz-scope-(us)-auction-ends-8613-evening-no-bids-yet/msg272667/#msg272667

[mkpak93]

Thanks a lot guys yeah I'm looking into the hitachi v212 dual channel 20 MHz , have any of u guys had any experience with this? Should I go for one with a higher frequency, say 50Mhz, or is 20 fine in terms of being a beginner? Once again thanks this is good

[grumpydoc]

The v212 should be perfectly fine as a first oscilloscope. There's a user manual at http://mpe.berklee.edu/documents/studio/manuals//testingmet/Hitachi%20V212/V-211%20V-212%20Operation%20Manual.pdf.

Obviously if you can get a 50MHz 'scope that would be slightly more flexible, especially with microcontroller projects. A 20MHz 'scope is going to show a reasonable representation of a square wave up to 4MHz or so. Anything much faster will tend to start to show as a sine wave but faster signals are likely to be things like clock signals where a lot of the time you just want to know that it is present and not stuck high or low.

As to buying one off ebay - to an extent you have to accept that as you aren't buying a new item there is a chance it won't be 100% and for all sorts of reasons you might find a scope described as "used and working" doesn't and a scope marked "for parts only" is fine and will give you years of trouble free service.

c4757p's comments are spot on. If the photo shows a sharp trace then it tells you a fair bit of the 'scope is OK. One caveat is the Hameg 'scopes with a component tester - I see a lot of photos of these 'scopes which are obviously showing the component tester trace. The give-away is that it only fills the central 8cm of the screen so there's a 1cm gap either side. This doesn't tell you quite as much about the 'scope because it doesn't involve the main timebase or trigger circuit or very much of the vertical amplifier.

I would avise caution if the trace isn't sharp though - as c4757p says it could just be badly adjusted but it might be PSU noise getting into the vertical AMP (not too bad, probably just needs a "re cap"), oscillation in the vertical amplifier (somewhat more tricky) or problems with the high voltage side - which might just be a failed resistor but you are then playing with about 2kV for most 'scopes.

If there are photos with a recognisable signal then that's even better.

If there's no trace but the listing says the 'scope is working ask the seller for some more photos - if possible with the 'scope showing at least it's cal signal. While this is intended for probe adjustment rather than as a test signal it's better than nothing and just about every 'scope in existence provides it - it only takes a suitable bit of wire from the cal output to one of the inputs to get some sort of display.

Hamfests are OK - in the UK prices are lower than ebay and you do get the opportunity to haggle. There's also a decent chance that the person selling the 'scope is knowledgable so can reliably tell you whether it works or not. On the whole I've found vendors at UK radio rallies fairly honest - of course there is a chance the vendor knows you'll never see them again and can palm you off with something that doesn't work but, again, you have to accept that goes with the territory.

Good luck!

[simpson]

eBay's "advanced search" allows you to limit searches to a distance you select from your location. This can save you a lot on shipping charges or, if the seller agrees, you may be able to pick up the scope in person and pay no shipping. This might also give you a chance to check out the scope before finalizing the sale.

[youbecha]

I just got a Tektronix 2445A off ebay (US) for $200 even. (+$22 shipping).

This particular one demo'd all 4 inputs with a signal, showed the diagnostics results.

So I figured it was close enough.

I just ran through the setup tests to make sure everything was calibrated properly (section 4 or 5 of the Tektronix owners manual)  and it is.

But it was still a bit of a gamble...it was a bit less of a gamble since they showed properly working displays.

I don't think you can do any better than just look at the description and view the display, some sellers will tell you exactly why they are selling as is...or what might be a problem.  The best would be to actually see it in person...


They are out there, you have to be patient.

[GreyWoolfe]

Youbecha, did you get it from KellyJo_13?  I have been eyeing one of them myself.  I am thinking of getting one and selling my BK 5100 and Tek 2235.