DIY Oscilloscope

[DonaldStott]

Although I was a bit overwhelmed by the number and intensity of responses to my "Which Digital Multimeter" question, I'm going to risk asking another along the same lines!

Any comments on the suitability of this: -

DSO138 2.4" TFT Digital Oscilloscope Kit DIY parts 1Msps

Just looking for some Projects to build over the next few months.

[ms660]

There's a thread on the DSO138 here:

http://golbornevintageradio.co.uk/fo...ghlight=dso138

Lawrence.

[ParcGwyn]

I have built 2 of these kits, one genuine and one a clone. They both perform reasonable well for audio work but are a bit noisy and quite slow, I have modified mine by the addition of an external trigger input. If you want a serious scope I would recommend a second hand analogue one, but for fun these kits are great.

Dave

GW7ONS

[DonaldStott]

Thanks Lawrence (again) and Dave for the quick and helpful responses.

I'm not yet experienced enough to consider a second hand analogue oscilloscope - just thought that this DIY kit would be both educational to use and fun to build!

[JayBee66]

Depends on what you want to achieve; build your own scope or buy a scope cheaply.

For £10-£15 more you could keep an eye on your local auction rooms. Not the fine art type, the house clearer type with a bolt on auction.

Analogue scopes, valve radios and the Hunts CRB3 that I bought recently were all picked up at such places.

I think any old analogue scope is better than a cheap digital scope. I have not been tempted by any digital scope. I don't feel as though I am connected to the device I am looking at. I like to see analogue curves not digital approximations.

[Craig Sawyers]

Worry not - I'm not going to chime in on this one

Craig

I'm not yet experienced enough to consider a second hand analogue oscilloscope

It will be easier than learning how to use the digital one. Honestly it is almost a pre-requisite of using a digital 'scope to learn how to drive an analogue one.

just thought that this DIY kit would be both educational to use and fun to build!

It will indeed, interpreting the results may however be a bit hit and miss unless you know what to look for. Analogue 'scopes don't have the oddities that cheap digital ones do (you can see waveforms that don't exist, it's down to the sampling nature of a digital 'scope). I own a digital 'scope and am happy with it, it did cost nearly a thousand pounds and has (almost) no oddities.

[Philips210]

Hi.

As others have said, it's best to start using an analogue oscilloscope first and I would recommend buying a good second hand one. There's no need to go for anything too extravagant, something like Scopex are quite good and German made Hameg scopes are decent and good value. Going up a notch and Philips are a good buy.

Regards
Symon.

[Ed_Dinning]

Hi Donald, lots of simple scope designs around that will be cheap and teach you an awful lot about scopes in the process. I believe there was a simple design in WW in the 70/80's that use virtually any 3" to 6" tube and a couple of ics.
Let me know if you want to go down that route and I may be able to get you some of the parts.
We had some of the electrical apprentices build this at the Thorn cooker plant. It made a great project.

Ed

[Diabolical Artificer]

I have a Farnell scope you can have for the postage/courier and a few bob for my daughter's piggy bank Donald.

Drop us a PM if interested. Andy.

[Diabolical Artificer]

Here's the manual ( sorry manual too big, here's page 1) as promised Donald. As I said this is for a different model, but the Farnell 30-4D looks similar and is pretty much the same inside.

A.

[Radio Wrangler]

I'll reinforce the advice to learn on an analogue scope.

Basic digital scopes have a lot of foibles that you'd need a fair amount of knowledge to work around them and not be confused by counter-intuitive results.

Digital scopes can do some amazing things, and just what a fairly basic one can be made to do in the hands of an experienced user is quite remarkable under favourable circumstances. That said, there are things which analogue scopes can do so much better. Ultimately one of each is the ideal.

The scopes built around PC add-ons usually take a lot of short cuts, you may not find a full range of input attenuation, so the voltages you can connect it to, even with a probe are usually limited.

There were lots of basic Hameg scopes distributed on this forum about a year ago, ex-university teaching lab that would have made a fine first scope. The Farnell one would get you going too, and it sounds like the price would still leave your treasury undepleted, so you could learn a fair bit and then ponder the issue of a digital scope kit, or a more comprehensive lab scope if you feel the need for more.

David

[julie_m]

One big advantage of a self-contained digital oscilloscope that nobody seems to have mentioned yet is the ability to be run from batteries; which prevents potential problems when working on live-chassis equipment.

I would recommend digital every time -- but then, I already knew how to use an analogue 'scope before I first touched a digital one. Knobs and switches might be easier to get used to than menus. Unless you're the sort of person who prefers to read the manual from cover to cover first before playing with a new toy, in which case you might be fine.

I would definitely not recommend buying buy a "fixer-upper", no matter how little the vendor says is wrong with it. You really need a working oscilloscope to mend a broken one .....

[MrBungle]

Good advice. I always end up with two broken ones.

[mole42uk]

I have a spare broken Gould 3000 in case the working one goes wrong - but it hasn't yet. Am I doing something wrong?

[MrBungle]

You've just stolen all my oscilloscope karma, that is all

Realistically back on topic, if it was my first scope I have no idea what I'd pick at the moment. The new digital ones (Rigol, Tek) that I've owned aren't all that great really. They are like driving a radio controlled car rather than a real one. You're getting a digital approximation of reality hiding behind the already analogue approximation the front end gives you. There is some serious lag in some functions. TBH I only use my hacked DS1054Z for slow speed capture. I can get a much better capture of periodic events with my rancid old Philips PM3217 I paid £10 for with delay sweep which has half the bandwidth.

Regarding scope manuals, I have never read a single page of one other than the service manuals (which indicates an issue if there ever was one!). Even the menu system on the Tek scopes is quite discoverable if you have a play.

I've talked myself into saying one of each (but not those cheap DSO kits - they're useless).

TBH I slightly wish I was into this in the early 1970s and had no money when a scope was an impossibility. Necessity drives purchases and that makes you learn to use the tools you have rather than long for ones you don't. In the early 1980s I had a VOM, a rather knackered motorcycle battery and that was it

[Junk Box Nick]

It was an old design back then but I built this one when I was at school. I was given a lot of parts which helped. The tube was the good old VCR138 but there was not a lot to the rest of the design which consisted of two valves if you went the whole hog and built the optional Y amplifier - which I did. (The rectification specified selenium rectifiers but by this time suitable semiconductor diodes were available.)

I can't remember the spec. The immediately obvious drawback was the non linear display which got increasingly cramped along the X-axis (the cover illustration is a little misleading in this respect!). I never did a lot with it - it was fun to make it work and I learned more from the construction of it than anything else. Its use was a little beyond me at the time and it was taking up space and so got put away. I found it when clearing out my parents' house. It probably hasn't been fired up in over forty years. 'Working when last used...'

I still have the magazines with the circuits and some VCR138 tubes which I came by later at a rally in one of my many junk boxes. I will look it out the articles and post some information if that is okay. It might be fun to see if I can get it going once more. (It was from aged junk box parts even then so it will have to be approached with care...)