asuryan:
I never used a oscilloscope so I really do not know what parameters
are important for what kind of tasks.
What kind of circuits or projects do you see yourself doing and using a scope on? Will you be looking at inputs vs. outputs? Audio? RF? Digital transitions? Any/all?
asuryan:
- Is that sufficient for a time to time hobbyist?
Once again, it depends on what you plan to do; IMHO - that scope is ok for a field toolbox when you have no other choice or means to carry a full scope or something else, other than that it is pretty lacking.
asuryan:
2. What CAN this device do for me?
Just what it's specs say, but basically, it can measure a single channel, resolve down to a 50 KHz signal (good enough for servos and audio - note that when you pick a scope, the stated bandwidth needs to be approximately 4x higher than the highest frequency you expect to measure), it can store those readings (for later comparison to others - note this is not the same as having a 2-channel scope/DSO), it has a function generator, etc.
If your needs are little, such a device can be handy; however, given that this device runs about 1/4 the cost of some 2-channel portable DSO's - you might do well to save your money (or purchase a used quality 2-channel analog scope - something by Tek, HP, Agilent, Fluke, etc).
asuryan:
3. What kind of stuff CANT this device do (because of freq limit etc.)?
Well - you can't compare an input to an output at the same time (you need a 2-channel scope for that); you can't reliably test for any signals greater than about 50 KHz (not enough bandwidth; this isn't to say you couldn't go beyond this limit, just that the signals will look "degraded"). Still, this scope can be useful for certain situations. If, however, you can find a used, better quality bench scope (something with a bandwidth of 20 MHz or more, dual channel - and if you can find it, DSO capability), and spend a bit more ($250.00 - 350.00 USD) - or go for a new full-on DSO (for around $4-500.00 USD) - and as long as you don't need portable battery power (as most bench scopes need to be plugged into a wall outlet - though I am sure you can find a new bench DSO that is fully portable) - might be a better option.
Also - if all you need to check are digital signals, then a logic analyser like the Salae device might be a better choice all around; but you can only check digital signal transitions with it - you can't look at any analog waveforms, and you can't (usually) check for ringing and other such digital signal quality issues like you could with other scopes. Really, a logic analyser should be used in conjunction with a regular o-scope/DSO; they are really complementary tools for some tasks.
Finally - don't try to go beyond 2 channels on a scope/DSO unless you have a bit of money to spend; once you go beyond about 100 MHz and 2 channels on a scope, prices climb to the sky quickly...
