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Topic: Which Handheld Oscilloscope? (Read 34306 times) previous topic - next topic

Cosford

Feb 04, 2014, 10:00 pm Last Edit: Feb 04, 2014, 10:45 pm by Cosford Reason: 1
Hi,

Between work and time spent doing projects at home, I'm looking into the route of a handheld oscilloscope. I have an old analogue bench one available to me at work and good bench ones at university, but I'm looking for something to use both at home and 'on the go' so-to-speak. (The little electronics stuff I do at work is based on systems which would be impractical to remove from a take to a bench).

Any recommendations (<£150 GBP or 250 usd$)?

Possibly also interested in a USB oscilloscope instead if they're generally better than portable oscilloscopes for the money. Still not quite as convenient as a handheld, but at least my laptop doesn't weigh 15Kg. ;)

Regards,
Iestyn.

polymorph

At this point in time, I'd strongly suggest you stay away from pocket and handheld 'scopes. I recently bought a DSO 203 aka DSO Quad, and I'm sending it back. Buggy, false claims of the analog bandwidth, etc.

There are plenty of smaller bench scopes that are very portable with decent specs. Hantek, Rigol, etc. Better to save a bit more than waste your money on junk.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

Cosford

The thing is, if what I buy isn't portable (IE, can run on it's own power, or from a laptop) then it's not of much use to me as I have scopes available for that either at uni, or at work.

larryd

Have you look at a USB logic analyzer?
Google Saleae for example.
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Cosford

#4
Feb 05, 2014, 12:51 am Last Edit: Feb 05, 2014, 12:55 am by Cosford Reason: 1
The Saleae logic stuff seems quite nice, but I need a general purpose oscilloscope. I don't believe that it can perform those sort of functions?

Is the DSO203 (Quad) really that bad?
Appears as though it would work nicely for what I need. I don't need to be taking accurate measurements etc, It's really just for verifying that things are or aren't working the way I expect them to.

Anything more precise can be done on a decent bench scope.

polymorph

I'd get a USB scope before buying an DSO 203.

Here's an example: At one specific gain setting, a square wave that looks fine on a Tektronix scope gains a nonexistent spike on the rising and falling edge on the display of the DSO 203.

Another: The output of the signal generator at 4MHz looks OK on the Tektronix. On the DSO 203, it looks like a sine wave. OK, so the bandwidth is about 4MHz. But at some timing settings, the screen shows this weird double-humped signal, while the Tektronix shows the actual output remains unchanged.

Another: The MCX connectors rely on the spring force of the metal. Not a good idea on a probe that gets moved around, like a scope probe. I've had problems with intermittent connections.

Another: It is really, really tiny. Only a 3 inch diagonal screen. My phone is larger. With a USB scope, at least you've got a much larger laptop screen.

Another: That fancy aluminum case may seem like a good idea, but if you connect the scope incorrectly to your circuit, or the circuit has a failure that puts its ground live, then the case of the scope goes live.

But you haven't told us your requirements.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

Cosford

I'm afraid I can't be too technical with my requirements.

I'm looking for a general purpose scope, that can look at logic, analogue signals etc, that is portable (either a handheld or USB scope to connect to my laptop).

It doesn't need to be accurate enough to take fine measurements, just enough to get the 'gist' of what's going on; ie, testing for signal waveforms etc.

In any situation where I do need accurate measurements, I can just use one of the bench scopes I have available to me.

fungus

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

cjdelphi


At this point in time, I'd strongly suggest you stay away from pocket and handheld 'scopes. I recently bought a DSO 203 aka DSO Quad, and I'm sending it back. Buggy, false claims of the analog bandwidth, etc.

There are plenty of smaller bench scopes that are very portable with decent specs. Hantek, Rigol, etc. Better to save a bit more than waste your money on junk.


The trick is to upgrade the firmware and use a 3rd party.. that fixed the issues you speak of.

fungus


The trick is to upgrade the firmware and use a 3rd party.. that fixed the issues you speak of.


Yep. The original firmware is junk.

Also replace Diode D5 (or just remove it), a 5-minute job that really really improves digital bandwidth.

http://essentialscrap.com/dsoquad/digital_bandwidth.html

It's obviously never going to replace a "real" scope but for signals up to a few MHz (anything an Arduino can put out) it's perfectly OK. I use mine a lot, it's a very valuable part of my setup.

Quote from: polymorph

false claims of the analog bandwidth, etc.


Your loss, IMHO.

If you really expected 72MHz bandwidth out of a $150 device complete with 2 probes then you didn't do your basic research (or read any forums).
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

polymorph

I just love how dismissive people are here. "You couldn't find the information that I already know exactly where to find, so obviously you are lazy and a loser." It is also great how everyone rounds down prices. I paid $175 plus $30 for two more probes.

Everyone selling this scope claims 72MHz bandwidth. Some claim that when using one channel, the ADCs double up and capture at 144Msps, so that claim of 72MHz doesn't seem outside the realm of possibility. At one time, a 10MHz scope was thousands of dollars. What is your point?

On Seeed Studio forums, there is a 12 page thread on the bandwidth. No one reached an agreement. Even Seeed Studio apologized for claiming 72MHz bandwidth, but never responded to what the actual bandwidth is. I did do a lot of searching, unfortunately that thread I did not find until after I'd bought it.

The Wiki has nothing on the actual bandwidth. The Wiki and everything else is very confusing regarding firmware updates. It took me a few days to figure out what the heck a ROM slot is, because everyone assumes you know, and so doesn't describe it.

So if you are done insulting me, I'd like to politely ask you which firmware you use, and where would I find it? I've not returned this scope yet. I'd love to be able to use it.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

fungus


Everyone selling this scope claims 72MHz bandwidth.


Where does it say that? All the official pages say 72 megasamples/sec sampling rate.

http://www.seeedstudio.com/depot/DSO-Quad-4-Channel-Digital-Storage-Oscilloscope-p-736.html


Some claim that when using one channel, the ADCs double up and capture at 144Msps, so that claim of 72MHz doesn't seem outside the realm of possibility.


Sample rate isn't the same as bandwidth.

Bandwidth depends on the capacitance of the entire system.


The Wiki has nothing on the actual bandwidth.


Somebody's bound to disagree no matter what they say.

My advice: Stop obsessing about bandwidth and decide if this device is worth $175 to you.


So if you are done insulting me, I'd like to politely ask you which firmware you use, and where would I find it? I've not returned this scope yet. I'd love to be able to use it.


Me? I use the one that's in the sticky at the top of the Seeed Studio forum for "DSO Quad".

http://www.seeedstudio.com/forum/viewtopic.php?f=26&t=2957

There's also another sticky for "Logic Analyser", etc.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

polymorph

#12
Feb 05, 2014, 05:58 pm Last Edit: Feb 05, 2014, 07:45 pm by polymorph Reason: 1
Thanks!

Everyone selling it on Amazon, Rakuten, and SainSmart claim "72MHz analog bandwidth". Seeed Studio used to claim 72MHz analog bandwidth. Some claim 8MHz, some 30MHz bandwidth. There are eBay auctions claiming varying bandwidths.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts

CrossRoads

#13
Feb 05, 2014, 06:31 pm Last Edit: Feb 05, 2014, 06:34 pm by CrossRoads Reason: 1
Does it really need to be handheld, or just small & portable?
The small benchtop units like this 200 MHz scopes like this GW Instek 4-channel scope are pretty compact. About the same width as a 15" laptop, half the depth, lower in height, and this particular model, GDS-2204A, weighs under 10 pounds.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

Or maybe something like this is all you need.
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERY
The electrical engineering students at RPI were required to buy one to use in sophomore classes.
Will see if I can get some feedback from my son about it.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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