What kind of oscilloscope should I buy?

Hi!
I'm a proud owner of a fully working Tektronix oscilloscope from the late 70s. The only problem is that this thing is really big, and it's often kinda overkill when it comes to measuring arduino signals.

Therefor, I'm thinking about buying a new, handheld oscilloscope. I Don't have such high budget, maximum 200$

I've been kooking for the dso nano v1, a cheap (~60$) oscilloscope with only one channel
http://www.ebay.com/itm/New-Mini-Nano-ARM-DSO201-Pocket-sized-Handheld-Digital-Storage-Oscilloscope-/170888941630?pt=BI_Oscilloscopes&hash=item27c9c6503e

The other scope I've been looking at is the DSO Quad, a two channel oscilloscope staring at ~160$
http://www.ebay.com/itm/ARM-DSO203-Quad-Pocket-4-channel-Digital-Oscilloa-scope-with-Aluminum-case-ge-/251204517961?pt=UK_ToysGames_RadioControlled_JN&hash=item3a7cf4c049

Is there a big diffrece between these scopes exept that the Quad have 2 channels and a better screen?
And what about the benF firmware? is that a good choise?

This little guy works well
http://www.pdamusician.com/dpscope/buy_it.html
I got mine when they still offered them as kits.

Currently I’m using a borrowed UNI-T UT81B multimeter. It is fine for Arduino projects, although a bit slow on when it comes to display refresh rate.

I am also looking for a basic oscilloscope, but I’ve heard that I should stay clear of anything USB based, since an operator error can easily fry the PC. Any truth in that?

For microcontroller work you might also consider a logic analyser.

I've got a DSO quad and I'm very happy with it for Arduino work. You need the extra channels. Really. (it's actually four channels - two analog and two digital - hence the "quad"). A four channel 'scope with four probes for $160 is really a steal.

I use this firmware: GitHub - pmos69/dso203_gcc

Firmware thread here: DSO203 GCC APP - Community Edition (2.51+SmTech1.8+Fixes) - DSO - Seeed Forum

Important!
The Quad has a design flaw: The ESD protection diode on the digital inputs was badly chosen and has a high capacitance. This severely limits the bandwidth of those inputs (to about 1MHz!)

I don't know if they've changed the diode in newer production runs but if they haven't you'll need to either remove it completely or replace it with another one. Opinion is divided on how necessary the diode really is.

Full details+discussion here: http://www.seeedstudio.com/forum/viewtopic.php?f=26&t=1978

I replaced mine with a Texas Instruments TPD2E009DBZR. They cost 27 cents each on Farnell, but I got mine direct from TI as a free sample. 8) With the new diode my quad happily displays any signal the Arduino can output.

Anything's possible. If you put a high enough voltage on something you can damage anything.
If you're just looking at 5V signals associated with your arduino you are not l ikely to damage anything on the USB side, most likely you will just ground a signal on your circuit by putting a scope probe in the incorrect place.
If you're looking at 120V signals, then you need to be careful you don't zap yourself as well.

They will have to pry my Tektronix analog oscilloscope from my cold dead hand. :wink:

Lefty

They can have mine. Old RM503 model. Worked great for analog stuff back when I was college age, 60 KHz bandwidth was plenty.
Now the trace is pretty faint, and its not good for digital at all. Even the simple USB scope with storage capability is better for anything at all.

I've got a '70s analog scope, too.

It still works great, and the fine detail you can see in the CRT trace is amazing after you've been using pixellated digital scopes for a while.

For Arduino work though, I'll take the DSO Quad every time.

fungus, I'm thinking about getting a DSO Quad, since it can be used as a logic analyzer (perfect for serial RX/TX and i2c).
I've also been looking at recommended firmwares.
You said your formware was the GCC APP firmware. I think the UI looks a bit complicated, so I found gabonator's little baby; GitHub - gabonator/DS203: DS203 quad oscilloscope firmware compatible with gcc

May I ask, What kind of apps are you using? do you have some recommended apps? have you tested the Quadpawn app?
Sorry about all these questions, but I'm just so curious about this little, open source scope! how much better will the bandwidth if I either remove (saw it in a guide) or relplace it?

Thanks!

There are some really tiny breadboard mountable scopes which look enormous fun: http://www.gabotronics.com/development-boards/xmega-xprotolab.htm - I haven't tried one personally but the price is reasonable for what it is I think.

I actually use my cheapo (<50$) logic analyser most of the time, OLS, Open Logic Sniffer , Open Bench Logic Sniffer - DP.

Doesn't help with analog signals.

MarkT:
There are some really tiny breadboard mountable scopes which look enormous fun: http://www.gabotronics.com/development-boards/xmega-xprotolab.htm - I haven't tried one personally but the price is reasonable for what it is I think.

I have a Xprotolab and it's okay for occasional hobby use but you need good eyesight as the OLED writing is tiny. It also has a PC interface that I have not tried.
I also have a Scanalogic2 logic analyser for hobby use and I think it's really great.

CrossRoads:
Doesn't help with analog signals.

I think he knows that.

Here's my advice ...

I have a digital scope, and a logic analyzer. And what do I use every day? The logic analyzer. I use the scope maybe once a week.

For $149 you get a lot of useful features.

You can capture 10 billion samples! Try doing that with your scope! Unless you are prepared to spend tens of thousands of dollars.

It interprets serial, I2C, SPI, CAN, Manchester, and other stuff. So rather than counting 1s and 0s the actual data is displayed (as above).

The Arduino is a digital device, basically. Analyzing digital data is more important than analog. Of course analog is useful if you are trying to get to the depths of why a circuit is not working. But the logic analyzer is really, really, useful.

hansibull:
fungus, I'm thinking about getting a DSO Quad, since it can be used as a logic analyzer (perfect for serial RX/TX and i2c).

I was working on an I2C driver for an ATtiny a few days ago. I would never have fixed it without my Quad to look at the lines.

hansibull:
I've also been looking at recommended firmwares.
You said your formware was the GCC APP firmware. I think the UI looks a bit complicated,

It's not massively intuitive, no, but it's way more useful than the original firmware.

hansibull:
so I found gabonator's little baby; GitHub - gabonator/DS203: DS203 quad oscilloscope firmware compatible with gcc

May I ask, What kind of apps are you using? do you have some recommended apps? have you tested the Quadpawn app?

I honestly haven't tried many of them.

hansibull:
Sorry about all these questions, but I'm just so curious about this little, open source scope! how much better will the bandwidth if I either remove (saw it in a guide) or relplace it?

The difference is like night and day. With the bad diode in place any digital signal above 1MHz comes out as a flat line (I could see signals on the analog inputs but not the digital inputs - it should be the other way around!) With removed/replaced diode everything was perfect.

I don't know the new bandwidth limit because Arduinos can only output signals up to 8MHz. I know it shows 8MHz perfectly.

There may be wisdom in this, too.

(if you already have an analog 'scope for the times when you need one...)

Quote from: Nick Gammon on March 05, 2013, 07:29:26 AM
Here's my advice ...

I have a digital scope, and a logic analyser. And what do I use every day? The logic analyser. I use the scope maybe once a week.

About a month ago I also have this question.I tend to a logic analyser Saleae product. It really worth every cent spent on it. I also buy a digital scope.It was my Christmas gift XD
I bought a Rigol DS1052E | 50 MHz.
But I don use it very often.
I suggest follow Nick Gammon advice

I currently own a Tektronix 2213 dual channel 50 MHz O'scope... and I am with lefty on "Prying..." Almost...
I want to be buried with mine. My next serious purchase will be the device that Nick Gammon uses.
I have Long been an admirer of Saelig, I remember them when they were 'New" too. No one stays in business as long as they have been without good reason and I aim to buy a piece of that reason.
I use my scope for things analog mostly... But with 2 input channels and an external sync 'input' I can display a lot of things.. 'digital display..' but it is still, analog.. Delayed sweep was the only advantage I had in a situation where I had to display both sides of an RS232 'conversation'.
The point is that the best idea is to use the best tool for the job and an analog scope is a fine addition to any persons "Tool-Box"for analog work. Most of the stuff I see here however could be done as well with an LED and a driver transistor (Logic Probe?). In my direct experience an O'scope has NO comparison to a Logic Analyzer... and the Logic Probe is best for looking at pulses... If you aren't fortunate enough to own an O'scope/Analyzer.. The reason is simple.. many pulses will get under sampled by poor refresh rates of cheap DMM's but the human eye responds well to 10 mS pulses. Few DMM's are capable and I wouldn't want to put my Fluke 179 to that test.
An O'scope was intended to look at one or two things at a time. Try to use a 4 channel scope on the inputs and outputs of a stereo amplifier sometime. The data on an average 5" screen is worthless except for things heard easier than seen, although displayed accurately... in a 25 mm wide window perhaps 10 cm long. Due to the display limitations the ear will pick up defects long before they are apparent on the O'scope.
I should Never try to write before 6 AM. {Edit RKJ}

Bob