affordable scope ?

[savuporo]

i have a really old analog scope that is like 20kg in weight and two channels, its a PITA to use and takes up tons of desktop real estate, and is pretty limited vs. modern DSOs.

I went looking for something affordable and found that there are several PC-based USB scopes out there, a good comparison chart of several is found on
http://www.cleverscope.com/ main page.
Cleverscope itself, however, is like 1000$ which is a significant chunk of cash, way more that i wanted to spend, although for more professional use surely worth it.

One more thing that i found is USBScope50 which is a really really lowcost device, http://www.elandigitalsystems.com/measurement/usbscope50.php
Comes with full sources of software as well.

Any of you have direct experience with these USB scopes ? Features per dollar, what would you get ?

I am really currently interested in getting three channels ( guess what .. ) of voltage on PC but down the road i'll probably want more features again .. so spend either $350 now and look for something more capable later or..

[mmormota]

I am happy with my cheap Velleman PCSU1000. There are many better scopes, but it works well, good for the price.

[jeffs555]

One more thing that i found is USBScope50 which is a really really lowcost device
Doesn't seem that lowcost to me. Price I saw was $390 USD for a single channel. The two channel Velleman seems to have about the same specs, and costs less.


If you really need more channels, how about this one? http://www.teampctechnology.com/product_detail.php?id=444

Don't know anything about it, but it has 4 channels for only $765. This one is only 5 Ms/s but they have versions up to 50 Ms/s. My guess is that your need for 3-channels has to do with brushless motors, so 5 Ms/s should be high enough.

[jeffs555]

Another option for more channels would be to build an input multiplexer. I seem to remember in the vacuum tube days seeing several projects to get two channels out of a single channel scope. They multiplexed the two inputs into a single channel(like chop mode on 2 chan analog scope). They added a DC offset to one of the inputs so the traces were separated.

You could use one of the video multiplexers from Maxim-ic, or even one of the cmos transmission gate multiplexers.

[savuporo]

"Price I saw was $390 USD for a single channel."

From what im reading, it is configurable for up to 4 channels, while dropping the max sampling rate accordingly ( i.e. you are not going to get 75mhz on all four channels, but roughly 75/4 maxx ) but thats plenty enough for a 15-khz PWM monitor.

The Handyscope link posted looks suspiciously similar to CleverScope .. ??

Can you hook Velleman DSO up to PC and upload data ?

[thirsty]

try www.bitscope.com - they even give away the schematics of an earlier version if you feel up to building your own :)

[andrewm1973]

Its a bit homely looking but

http://www.fpga4fun.com/Hands-on_Flashy.html

will get you 100MS/S for $80 USD.

They have 2 channel versions as well.

[jeffs555]

From what im reading, it is configurable for up to 4 channels, while dropping the max sampling rate accordingly ( i.e. you are not going to get 75mhz on all four channels, but roughly 75/4 maxx ) but thats plenty enough for a 15-khz PWM monitor.

The way I read it, it is a single channel usb scope which can be stacked together. To get additional channels, you need to buy additional scopes. To get 3 channels would be about $1200.

Can you hook Velleman DSO up to PC and upload data ?
While Velleman does make self contained handheld scopes with lcd display(some have rs-232), the PCSU1000 is a usb scope much like the others discussed here.



PS The BitScope BS310U at $495 appears to have 4 analog channels. Two are normal 1meg BNC inputs, and two are 100k inputs on a 25 pin D connector which also has digital logic analyzer inputs.

[savuporo]

hey, that Velleman PCSU1000 appears pretty good for about $350 as well, i didnt know they make stuff like that. Thats a good option i'll consider, from known good brand.
They make a $130 single-channel version as well.
Here is the lineup:
http://www.velleman.be/ot/en/product/list/?id=366976

Edit: froogle came back with $230 for a PCSU1000 search, yay ! my local electronics distributor sells it for about $600 though :&

[xorcise]

CircuitED (http://www.circuit-ed.com) is now a US dealer for the new PoScope, and we should have them in the next week or so. It's a USB 2-channel PC Oscilloscope, 16-Channel Logic Analyzer, Signal Generator, Spectrum Analyzer, etc., with a full bundle of software, probes and clips for less than $200 USD.

Since we develop with MCU's we especially like the UART, I2C, One-Wire, and SPI protocol analysis tools in the software.

Here is an overview:
http://po.labs.googlepages.com/usbosciloskop

[andrewm1973]

at 200Khz sampling the PoScope is a bit on the average side isnt it ?

It looks good as a logic tool maybe, but I would hardly be pushing it as a scope with only slightly better specs than a sound card.

[Gordito Volador]

xorcise,

That's good to know. I bought my PIC development kit at CircuitED and am very happy with it. Looks like I'll have to get a PC scope from you guys as well.

Regards, Bill

[mmormota]

at 200Khz sampling the PoScope is a bit on the average side isnt it ?

It looks good as a logic tool maybe, but I would hardly be pushing it as a scope with only slightly better specs than a sound card.

My soundcard (simple Nvidia main board chipset) is working very well at 192 kHz sample rate with this great free program: http://www.zeitnitz.de/Christian/Scope/Scope_en.html
It was so good that I seriously considered a modificaytion of the soundcard to handle DC. (the soundcards have a capacitor on the input)
Honestly, a soundcard scope is affordable for most usual diy uC project.

Finally I decided to buy the Velleman because of the way higher sampling rate etc.

[andrewm1973]

wow - thats cool - i thought the sound cards had 96khs sampling. shows how little I know.

[savuporo]

http://po.labs.googlepages.com/usbosciloskop[/QUOTE]
Hmm, that looks even better for Motor control/MCU work, except .. whats the isolation level between the probe and USB port ?
can it handle 240V line input with the 1:10 probe ?

[mmormota]

Hmm, that looks even better for Motor control/MCU work, except .. whats the isolation level between the probe and USB port ?


It is just slow for motor control work.

[savuporo]

It is just slow for motor control work.
How so ? PWM runs usually in tens of KHZ ranges ..

Another thing i wanted to ask, is there an option to gang two of these together for synchronized four-channel device, preferrably in the same user interface ?

[rmteo]

xorcise,

That's good to know. I bought my PIC development kit at CircuitED and am very happy with it. Looks like I'll have to get a PC scope from you guys as well.

Regards, Bill

I agree with you, Bill. Warren is a stand up guy.

BTW, are you still looking at doing the 80pin to 40DIP adapter?

[mmormota]

How so ? PWM runs usually in tens of KHZ ranges ..

Another thing i wanted to ask, is there an option to gang two of these together for synchronized four-channel device, preferrably in the same user interface ?

The signal on the brushless motor pins is pretty complicated. PWM, BEMF, inductive spikes in one mix. And you try to figure out this shape from say 5 samples in a period... ;)


I built several DIY brushless controllers designed by quax. The soundcard oscilloscope was useless, I had to use my old (but good) analog scope. (The Velleman is newer, I didn't have it that time)

[xorcise]

Regarding the PoLabs Oscilloscope, we know that it's slow for high end work, but ideal for a lot of microcontroller work, especially with the 16 channel logic analyzer and the protocol analysis features. We think that it's got some bang for the buck. It certainly doesn't replace my 100MHz dual-trace scope, but it does things my big scope can't. It can be used in audio work quite nicely and has a spectrum analyzer.

rmteo, I haven't given up on your breakout board idea, just been too busy lately to think seriously about it. Looks like a nice design.

[savuporo]

The signal on the brushless motor pins is pretty complicated. PWM, BEMF, inductive spikes in one mix. And you try to figure out this shape from say 5 samples in a period... ;)
I know it can get complicated .. my initial goal is just to see the low khz range at low power outputs, but i may be thinking too short-term. A few days later i'll be probably wanting higher frequencies as well. Im currently hoping my old analog scope will help out there, but the USB Velleman looks increasingly like a best bang for the buck for my near-term needs ..

[xorcise]

Saw this offer in my email....looks like a nice unit for the price:

http://www.tequipment.net/OWONEDU5022.html

[jeffs555]

There was some discussion of that Owon scope in this thread. http://www.rcgroups.com/forums/showthread.php?t=613377&highlight=owon

There is a lot to be said for having a scope with a built in display, and the price is about the same as the usb scopes without display. It does have a usb interface, but it doesn't send real time data over the interface, only captured data.

[rmteo]

Looks like they have that 25MHz scope on sale for $329 here:
http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=PSSA002&Category_Code=

[savuporo]

There is a lot to be said for having a scope with a built in display
Well, im thinking exactly the opposite. When i work with electronics, i have my laptop with nice big LCD always with me anyway, and if i need to see the signals in the system, there is a high chance that i wanna sit back, and take a careful look at them. I like PC-based software better for that than a set of fixed-function knobs.