Oscilloscope Tutorial Part 1 - Choosing an oscilloscope


Uploaded by Afrotechmods on 27.09.2008

Transcript:
This is the first part in a multipart series of videos about oscilloscopes.
In this first video we're going to answer these questions:
Oscilloscopes... What are they? Why would I need one?
Which one do I get? And where do I get one?
First question: What is an oscilloscope?
An oscilloscope is a device that lets you view changes in voltage over time.
Volts go on the vertical axis, and time goes on the horizontal axis.
You can change the scales of the axes to measure tiny signals or large signals,
fast-moving signals or slower signals.
So why would you need an oscilloscope?
Well let's say you are trying to build a dimmer circuit for your headlights and you need to see if
it is going to work first before you connect it to your car.
An oscilloscope can show you whether the circuit is behaving correctly, or if you need
to fix something.
Or let's say you are trying to build one those headphone amplifiers that fit in an altoids container.
Don't you want to make sure that your circuit is working right before you connect it to your
$200 headphones?
Basically trying to analyze a circuit without an oscilloscope is like trying to
paint a picture without your eyesight.
The oscilloscope allows you to fix small problems before they become
big expensive problems.
If you are serious about your electronics hobby you NEED an oscilloscope.
So which oscilloscope do you get, and where do you find one?
Brand new oscilloscopes are normally really expensive, reaching into the $1000 range.
But if you buy a used oscilloscope you can get one for a few hundred dollars.
To give you an example I've never paid more than $400 for
an oscilloscope ever.
So let's go on eBay now and see
what options we have. Search for "oscilloscope".
You can see a lot of oscilloscopes here with bandwidth numbers. I'd recommend
getting one with at least 10 MHz bandwidth, but don't bother with anything
higher than 100MHz because you are never really going to need it.
If you see oscilloscopes listed with Megasample ratings, 100 megasamples per second (100MS/s)
or higher is good.
Don't worry if you don't understand what those mean just yet. Once you've
used your oscilloscope for a while it'll become clear.
Now in terms of brand names the best oscilloscopes you can get are H.P.
Tektronix and Agilent. Rigol is good too.
So the next question... do you get an analog oscilloscope
or do you get a digital oscilloscope?
You can save some money by getting an older analog oscilloscope and that might be all you
need if all you are working with is analog circuits. However a digital oscilloscope will
have some nice advantages such as being able to measure voltage and frequency for you.
And it will allow you to save waveforms to analyze later.
If you ever intend to work with microcontrollers or serial communications,
I highly recommend a digital oscilloscope.
Nowadays you can also get cheap USB based oscilloscopes that you can plug into your laptop.
Generally speaking I stay away from these in case you connect
something wrong you don't want to risk destroying your laptop.
Also standalone oscilloscopes tend to have higher ranges of voltage that you can measure.
I would only get a USB based oscilloscope if you seriously cannot afford
a better stand-alone oscilloscope.
A one channel oscilloscope is ok but if you can afford it I'd highly recommend
getting a 2 channel one because it's going to make comparing waveforms
much easier.
A 4 channel oscilloscope is probably too much for your first time.
Finally use your common sense.
This is eBay so don't buy an oscilloscope that is described as untested or "as-is."
Make sure that you see a listing with a picture of the oscilloscope
powered on and measuring something useful.
It's not always necessary to have an oscilloscope that is precisely calibrated
but if you can get one for cheap then go for it.
Now if you don't want to bother with eBay you can actually get a brand new
oscilloscope for cheap.
This is the oscilloscope I just bought.
$287 brand new from www.saelig.com and they even shipped it to
Canada for me.
As you can see it works just fine.
So now you've got an oscilloscope watch my next video and I will show you how to
use it!