$50 Oscilloscope worth the money for a hobbyist?

[SETEC_Astronomy]

Anyone care to chime in on whether or not this ( http://www.seeedstudio.com/depot/digita ... p-167.html ) is worth money for a hobbiest. The type of stuff I do is typically low speed (under 1MHz), i2c, spi, rs-232, etc... Let me know what you think. Is it better to save up and get a real scope or is the above a good starter scope?

[Robert Reed]

Amazing little device, but the key word here is' little' . Having grown up with scopes and using about every major manufacturers units and dozens of their models, I am firmly engraved in large screen real time scopes. That unit as cute as it may be looks very inconveniant and limited in operation. I think that after using it for a few days, you would be drooling for a 'real' scope. The 1 MHz stated bandwidth is not clarified as to what - 3 db down? Remember even a slow speed but high fidelity square wave will require a scope response 100 times the square wave rep rate for faithful reproduction reqiring a much larger bandwidth than would initially suspect. If it were me, I would put that $50 towards a step up of performance in a more usable scope. Boy I hope this doesn't sound like a plug, but I just happen to have a great scope thast has been sitting around for a couple of years since I bought my new Tektronix. It is a 60 Mhz Protek loaded with features and has 10KV accelerating voltage for a very crisp dislay. Paid $1050 for it nine years ago and it is still in the same shape now as when I took it out of the box. If interested,give me a PM and I will fill you in on the details.
PS- with all your efforts in helping me in the past, you know I wouldn't steer you wrong.

[Externet]

Hello Setec.
That small oscilloscope is good when you have to work on telephone lines, as battery powered provides isolation; or work on car electronics, good when you permanently add it to a project front panel.

I have six fingers on mi right hand. One of them is a probe. All day working with one. Have 4 at home.

For 'real' measurement use, get a large screen, two channel unit. Much better option to learn too.
There is many great not Tektronix oscilloscopes at much lower prices, surprisingly affordable. Tour ebay.

Miguel

[Lenp]

Setec

I think that after using it for a few days, you would be drooling for a 'real' scope.

For 'real' measurement use, get a large screen, two channel unit. Much better option to learn too.

I second these opinions!
The term cute might apply, but effective does not. Just the thought of a new $50 scope concerns me. I have paid more for scope probes than that! Not being dual trace is also a turnoff. Owning and using HP and Tek scopes for years I wouldn't look twice at this 'instrument' even as a starter. Just a few more weeks savings will put you in a position to consider many of the 'vintage' scopes that have far better qualty and features. These are are available through surplus centers and ebay, and maybe the deal that Robert may make!

Len

[SETEC_Astronomy]

Thanks for the input everyone. The point is clear and I'm glad I asked, personal experience is valuable. I've PMed Robert.

[Lenp]

IMO..You've made a wise choice!
Len

[SETEC_Astronomy]

I agree, I think I'll be quite pleased with the outcome.

[MrAl]

Hello there,


I have to agree with a lot of the suggestions already noted here. The bandwidth is certainly limited but
that is the calculated bandwidth too and not the real bandwidth. 2MS/s is not very good at all, even
though it may be useful for audio work but that's about it. When i designed a digital scope way back when
i realized that 100MS/s was the very lowest possible sample rate that would be acceptable, and even that
isnt that good really. Sorry to say, because the price is good for that little unit and the unit is self contained
in that you dont need anything else with it (i dont think).

A possible use i can see for it might be to use it as a display screen, where you build your own 100MS/s
(or faster) digitizer and port the output in slowed down time, where say 2us in equals 200us out or
something like that. This wouldnt be that hard to do because it is all digital after the high speed sampling.
Analog Devices make some pretty decent high speed digital to analog converters for part of the front end.
Of course this is for someone who doesnt mind a little work before they can use it.

[Bob Scott]

I just got an idea for a great budget oscilloscope!

I figure two stepping motors for the H and V connected to the knobs on an Etch-a-sketch, and a microcontroller. I just have to flesh out a way to tilt it and shake it every second or two.

Bob

[Dean Huster]

Bob, just use an old flatbed plotter. That way you can have a hard copy as well. Just swap out the paper to "erase". Don't have to worry about working out a stepper motor interface to the Etch-a-Sketch knobs, either!

Nice thing is that your input electronics can have the required gigahertz speed while your display can plod along -- not all that much different than a DSO with LCD display.

Dean

[jimmy101]

Heck, you've already got a "$50" Oscope. Just use the sound card on your PC or laptop: 48KHz, 16-bit, dual channel recording Oscope.

There are a couple freeware apps available for using the soundcard as an Oscope. You usually can't do DC measurements but anything in the audio range is a piece of cake.

Just have to be careful with the voltages Probably not a good idea to, for example, use the MIC input of a pc to try to record the ~30,000V spark of an automotive spark plug.

I usually just put two generic diodes across the input to limit the total voltage swing to ~+/-0.7V to protect the soundcard.

If you use a MIC input (instead of a line input) you also typically get ~2.5V at 1mA of power on the wires. Very handy for powering a simple external detector circuit.

So, save your money and make do with the soundcard until you can afford a "real" Oscope.

[Bob Scott]

Bob, just use an old flatbed plotter. That way you can have a hard copy as well. Just swap out the paper to "erase". Don't have to worry about working out a stepper motor interface to the Etch-a-Sketch knobs, either!

There you go, Dean!
Remove the stepper motors from the flatbed and screw them onto the etch-a-sketch knobs. Leave the old flatbed interface connected to the motors. Then, pick up one of those butt vibrating devices they sell on infomercials (the ones where you can eat like a pot-belly pig, yet still lose weight. No exercise necessary, the batteries exercise for you!) Set the newly created "output device" on the buttcerciser to erase as necessary.

Then enter the project in the new Nuts'n'Volts junk-box contest.

[Robert Reed]

Bob
Sounds about as useful as any 'inventions' that come out of those contests - you would probably win. And to boot - look at all the paper you save

[Dean Huster]

You'll still have to add a digital camera for hard copy. I guess you could place it on the platen of a photocopier and get a copy -- you just have to figure out how to mount the copier upside down and get the toner to work right so that you don't erase the Etch-A-Sketch in the process.

If Ohio Art (the originator of the E-A-S) could have forseen the high-tech applications of their invention!

Dean