First, allow me to apologize if this post is in the wrong forum. If so, please tell me the correct one and I'll repost it there.
I want to purchase an oscilloscope. I have never owned one in the past. I've read one at work that has already been set up for me by a knowledgeable person. Outside of changing the scale and reading the screen, that's my only hands on experience.
At the moment, I want to use it to measure noise in various projects, but think it will become more useful as experience is gained through use. I'm looking for anyone to dispense some advice as to what features to look for and how much I should spend for an instrument used for a hobby, not a career. From what little I know, the following represents the only features to ask about. There must be more.
Frequency capability.
One or more channels. They frequently used two at work. (NASA space program)
Digital or analog. Are there models that do both?
Ability to record screen shots to a USB key.
Small hand held or benchtop.
New or used.
Any particular brand.
Where is the best online site for learning how to use.
Depends on how much money you want to spend and what you’re measuring. Today’s general purpose low cost entry scopes are good for 70-100MHz. Some can be hacked to 300MHz and above. Or you can pay for the increased bandwidth if so inclined.
One or more channels. They frequently used two at work. (NASA space program)
Again, a money issue. Two minimum, four is better.
Digital or analog. Are there models that do both?
Digital, no debate. Analog scopes are dead technology.
Ability to record screen shots to a USB key.
Most modern digital scopes provide it. Older digital may not (example: Tek 200 series)
Small hand held or benchtop.
Unless you have a specific use case for portable, bench top is the way to go. DO NOT buy a USB based scope. The only exception to that rule is the diligent analog discovery scope but again, that’s a different use case.
New or used.
New.
Any particular brand.
Rigol and Siglent are the market leaders in low cost decent products for hobbyists.
Where is the best online site for learning how to use.
You’re welcome. A full web google search for “which oscilloscope to buy” turns up several interesting links, this one has some decent info on the basics. It becomes much easier to make a decision once you decide on a spent limit. Only then can you start comparing features and decide which provides the best value and performance in your price range.
I also like that it came from Taiwan and not from China. I have grabbed screen shots from its USB stick port on the front and posted them here in the past. It accomodates add-in modules also; I don't have any.
larryd:
Use the search featured at the top of the screen.
We have discussed this same topic many times so there is a lot already here for you to read.
I’ve just looked myself. The search function has suffered badly as a result of all the recent “improvements” to the site and is nearly useless for such searches.
For threads about oscilloscopes, enter this a google search bar:
I want to use it to measure noise in various projects,
I guess before making a recommendation we should know more about your initial goal. Measuring "noise" is a tricky endeavor depending on what you mean by noise and to what level you wish to measure.
Measuring noise of a audio signal using a low cost oscilloscope is not going to work.
Beyond this I guess everyone has their own opinion.
At home I have a Tek TDS2022 which is a 2 channel 200 Mhz / 2Gs/s digital scope. 90% of the time I use only 1 channel. I've never needed the full bandwidth. I do have a Saleae 8-bit logic analyzer so I don't need my scope for logic testing.
Since you say you've only used a scope in work that was already setup for you I guess its fair to say you will be learning a lot when you get a scope of your own.
Aside from just working and being stable, I think one of the most important features of a scope is the trigger capability.
So my recommendation would be to get a "solid" 2 channel scope.
Unless you have a specific use case for portable, bench top is the way to go. DO NOT buy a USB based scope. The only exception to that rule is the diligent analog discovery scope but again, that’s a different use case.
It looks like everyone agrees on this and I have also bought a bench scope. But the limitations are severe: it is difficult to transport and the probes are referenced to earth so it is difficult to get differential measurements (and you need to be careful when placing the ground lead to prevent some short). It seems a scope connected only via USB to a (floating) (old) laptop would have some advantages.
If you are looking for a scope that does not have the probe ground connected to the scope AC power ground, you be searching for years. Easier to invest in an isolation transformer for the scope or for what you are measuring.
If anyone is interested, after much research I chose a Siglent SDS1104X-E. It has 4 channels with a lot of options including 16 digital channels (with purchase of extra probe of course). I know it's way more scope than a beginner needs, but I wanted a scope that would serve my needs for a long time. I didn't want to buy a less expensive one and find out in a years time I need to buy another with more capability.
Not sure, I would like to try my hand at fixing antique radios and other tube equipment. I'm thinking 2-5 amps?
In 45 years in electronics, have never needed one.
While doing internet searches, more than a few recommended using one if working on old equipment as they were built before polarized plugs and the chassis could have the hot side to ground. They warned of damaging the scope and/or yourself.
Use differential measurement 'or' a power cord with the earth ground removed (for that very odd time, use with care!).
I don't know what differential measurement is yet, but I'm sure I'll find out. Which device are you saying should have the earth ground removed, scope, item under test or both?
If you can't find a readily available isolation transformer, use two identical transformers with the secondaries connected to each other ans the output of the second transformer will duplicate your mains input voltage and you will now have isolation.
The old, old electronic equipment that was dangerous was the so-called AC/DC equipment. It did not have one side of the line connected to the chassis, but had a capacitor connecting the line to the chassis. Could still give a nasty shock!
Equipment instructions were to reverse the line plug if reception was bad.
However, you must ‘always remember’ the scope chassis will be at the ‘same level as your reference point’ and you ‘do not’ let the scope chassis touch any other equipment.
