buying the best oscilloscope

[turbo]

Your's is not old.
Mine is old.
It's a tektronix 556
And it's the best ive ever had.
Never liked the digital ones. 

Marco.

[Steven Dufresne]

thanks steve
can you elaborate what is 300VRMS.

300VRMS = 300 volts AC root mean square
It's a way of specifying the "average" voltage when the voltage is in the form of a sine wave (AC.) The actual average of a sine wave is 0. So to get some sort of useful "average", the voltage from the top peak of the sine wave to the bottom peak of the sine wave is multiplied by 0.707. The result is called the root mean square (RMS) voltage.

In this case it refers to the AC voltage that the scope can handle on input. So if N volts peak-to-peak times 0.707 = 300VRMS, then N=300/0.707=424 volts peak-to-peak. So my scope can handle 300 volts RMS, which is the same as 424 volts from peak to peak of the sine wave.
-Steve
http://rimstar.org   http://wsminfo.org

PS. @Marco, well I did say "relatively" old. And relative to yours, I bought mine yesterday! :-)

[Paul-R]

Don't spend money until you have an actual NEED to satisfy.
Remember that your first scope will teach you much about scopes,
but will be a failure. The second one will be a success.

Read this very thoroughly:
http://www.free-energy-info.co.uk/Chapter12.pdf

and to mess around with, you can experiment with a probe
plugged into the mic socket of your sound card, and public
domain oscillocope software from shareware.com, tucows etc.

Paul.

[Yucca]

Hi jasbir77

Every scope has a maximum input voltage beyond this level the input stage will be overdriven, As Steven mentions his is 300V RMS, thay´re all around that level, mine is 400V RMS. It is not wise to exceed that input voltage by too much.

Along time ago I borrowed a friends old 10MHz scope he had, he got it from his dad who´s work was "throwing it out", I was scoping the flyback on a coil that I´d built a joke electric shocker out of and I killed the scope

So whatever scope you get be very careful to not overvolt the input, and if you do want to scope across coils then try and get hold of a 100x probe or make yourself an attenuator.

Obviously it´s nice to get a scope as fast as possible, especially when working with coils and fast transients because a slower scope will smooth your peaks and not allow you to see the details. 50MHz or more is what I would aim for.

I would recommend getting a second hand one from a decent manufacturer instead of buying a brand new scope from an unknown manufacturer, the good makes are more rugged and you can get parts for them easier if needed. Plus you will sell it easier if you ever want to.

I have a Tektronix2431L, bought it second hand from a German surplus equipment supplier on ebay. I really like it because it has sampling for one shot analysis and is built really solidly (every Tektronix is!). A scope that samples is called a DSO (digital storage oscilloscope). If you can get sampling then it´s well worth it.

Happy scoping!

[MrMag]

Yucca,

I have to agree with you. Tektronix scopes have always been number one in my book. As a matter of fact, I have two of them. They are built very solid because they are used not only on the workbench but also in the field. There are a lot of them out there and if you can find one in your price range, I would highly recommend it.

Tim