Are you sure that's not just the AC-coupling doing it's self-centering thing?

Cheers

In case you are interested in downloading sampled data (and maybe later controlling) the scope using Linux, you may want to have a look at some stuff about the W2022A at Google groups.

Regards,
Falk

I was just having a look at DSOs on ebay and came across the google group for these CROs. This post is interesting:

http://groups.google.com/group/welec-dso/browse_thread/thread/dd72e1ad1d08c430

link to file:
http://welec-dso.googlegroups.com/web/FW...i-BwrUzBGT2hOzg

A year on was it a good purchase Mark? They seem to have disappeared from ebay.

They're still on eBay, selling 4-channel versions of the hardware now. It seems that most folks are picking those up for around US$400 or so, which is an okay deal if a real scope is out of the question due to price ($1400 and up) or size (bulky old-style tube scopes).

I like this little beast, and it lives on the workbench and is used from time to time for simple stuff. It's not as buggy as it was originally (firmware got updated slightly last summer), but it's a toy when compared with a "real" / expensive version.

EDIT: For example, it was just fine for debugging the empeg I2C timing last fall (mostly used my logic analyzer there, though) -- no issues at all with that. Ditto for when I was last poking at the temperature sensor circuitry.

I don't regret the purchase at all -- definitely do need a scope here, and anything else (w/200Mhz) was/is simply too much money for here and the little use it does see. So perfect for the weekend hobbyist, but not for a day job.

Cheers

Oooh.. there was even an April Fools Day (joke) posting about these.. very funny, but no warnings for the humour-impaired!

I'm a bit confused. Sure it's a joke? Maybe that recent post is, but there are posts about the firmware back in July 2008:

http://groups.google.com/group/welec-dso/browse_thread/thread/56f3c673928f18fb#

The firmware was released. That is what the 3rd party stuff is based on. The april fool is that they're sponsoring development and have a big list of desirable features I guess...

Yeah. We've had the source code (incomprehensible) since last summer. There's even a beta release from (unfortunately) April 1 2009 of a rework of it (mostly incomplete at present).

The April Fools is the announcement I linked to, of a development contract to fix the existing firmware and sell updates for $300 to existing owners. Yeah, right.

But like I said.. no smilies, so certain nationalities might not get it, and might even think it's a real deal!

Cheers

These days, now that I'm working with OTA television antennas (hobby), I'm really wishing for a 1GHz scope, to cover UHF television frequencies..

And I suppose if I had that already, I'd want a 3GHz scope for WiFi and satellite. But then I'd want a 6GHz scope for 802.11A. And so on..

Understand the need for bigger, better, more. Whilst I'm looking at a machine for a day job, it's also for home and coming out of my pocket (though it would be a tax dedcution).

I did have a quick look at the firmware. What a shocker. Basically all in one file...

Okay, how's this for clarity:

At US$400, *delivered*, I think a 4-channel 200Mhz scope like this is a pretty good deal, and way cheaper than any alternatives. It's slow, has the odd bug here and there, but it really does work.

And it has a colour display, decent menuing system, and takes up practically no space at all on the workbench. If I didn't already have one, I'd jump at the current offers!

And the auto white-balance on the 40D seems to work rather well.
With my previous camera (20D), that photo would have had a blue-green tint!

Cheers

Oh, forgot to mention. I did use the scope again quite recently, to actually *measure* the velocity factor for some RG-59 coaxial cable.

I'm making coax-loop baluns for some TV antennas, and it's very important to know how fast signals pass through the coax.

The nice thing about a scope this quick (1gs/sec) is that it only takes a few metres of coax to have sufficient delay that it can be measured on the scope!

The coax I had on hand here measured as a VF of 0.80c, which is quite close to the oft posted ballpark figures for RG-59 on the web (which range around 0.78 to 0.82 or so), for foam-core stuff.

Cheers

This reminds me of something I've been meaning to ask the board's opinion about. I'll put it in another post shortly.

A lot has happened with these scopes of late. Last summer, the (horrible) source code for the firmware was released, and over this past winter/spring some German chaps have been fussing away at it.

The current "beta" release of fixes/enhancements, based on the original factory firmware, is actually rather good. I've installed it on my own scope here, and most of the old bugs vanished, while some new features (re)appeared.

The FFT functionality has returned with a vengence, though it's still not useful beyond really low frequencies, and the scope is definitely a lot better behaved now.

The best thing with the new firmware though, is they've figured out how to reduce the inherent noise in the measurements, to perhaps half of what it used to be. This is good.

Related to that last point -- another person has been poking at the FPGA code, and determined that *all* of the visible noise is just the result of some firmware bugs. He's recoded some of the VHDL and posted youtube videos (search for welec) showing the difference. Quite astounding results, though it could be a long time before changes like that make it back in the new firmware releases.

Digging up an old thread.

We just bought a Rigol DS2000 series scope and it's brilliant. Because we're now doing a lot more analog stuff I find myself needing a lot more features out of the scope than I needed before and our old tektronix scope is just becoming more and more infurating to use!

We also bought a series 4000 function generator at the same time. We've needed a function generator for a while, I kept getting asked questions about our signal processing that I couldn't really answer without injecting known sets of signals into the front end, so hopefully I'll be able to give some definitive answers now.

Got to say that so far we're very impressed with the Rigol stuff.

Adrian

Has the state of the art in regards to osciliscope fronts ends for an iPad improved?

Is Oscium still the only player?

I don't need really high input bandwidth but I do need a large and high pixel display, hence the interest in using my own 'computer' for the user interface and display. And more than two analog input channels.

"Front ends"? From the looks of the photos on the Oscium main page, it looks like the iPad actually *is* the 'scope in some cases. The dongle has the test probes on it. That's kind of impressive. I didn't know anyone was doing that. Wow.

That's what I thought.

The scope (actually all the rigol equipment we bought) has usb and can be controlled with SCPI commands. This is particularly useful because 4 days out of 5 I'm hundreds of miles away from the physical scope and connected device. It's great to be able to remotely control it.

Same goes for the power supply, I can turn on/off channels set voltage & current limit etc.

And the multimeter, again I can set it into the mode I want and read back the readings etc.

So handy!

I had a good play with the scope yesterday and it's amazing for the price, not only does it feel physically solid (and expensive), the software doesn't seem flakey and it seems well thought out and comprehensive.

If only I could convince the wife that we needed one!

Adrian

When I looked at the Oscium it turned out it had no capture depth, ie it captured exactly one screenful, with no zooming possible. Not sure if that was just early software, but my dreams of pinch-zooming on a deep buffer died

Seems to still be the case

USB connected 'scopes' seem to be all over the low-end map, hard to figure out what is actually decent.

Well, many years later, and the Welec W2022A now has very usable third-party firmware, and a lot less noise on the signals. But I've decided to upgrade to a newer/better scope. There are now quite a few usable digital scopes with good bandwidth out there.

After a lot of reading/research, the perfectionists say to get something like a Lecroy scope, but those are horrifically expensive. In the budget category though, the Siglent brand is highly recommended. So I've ordered a 200Mhz 2-channel Siglent scope (1 gs/sec), for CAD$458+tax. The Lecroy 100MHz equivalent is more than 2X that price.

Real world reviews and measurements indicate the Siglent is the Real Deal, with actual 3dB bandwidth around 240MHz. The firmware for it has had regular updates and is working well.

Notice anything funny about the photos.. ?

The old Welec scope was imitating a more reputable Aligent's front panel, with totally different innards.

But in this case, Siglent actually designed the scope for Lecroy, but also sell it themselves! The two companies have quite a bit of their product lines "shared" like that.

It's displaying a waveform but there's nothing plugged into the probe connectors?

Two scopes, identical other than the Manufacturer's name at top left, and the considerably different price tags.

Scope arrived here today, and lives up to the reviews. Including the one on YouTube demonstrating a bug with the built-in UART decoder. A simple firmware downgrade took care of that bug, with no downsides I can see from the ChangeLog.

Cheers

I have not hunted for a ‘portable remote display/mobile app’ oscilloscope device in at least a year - has the situation improved?

Zoyi ZT-703S:

https://www.youtube.com/watch?v=kpzNVsSmUu0
https://www.aliexpress.us/item/1005006401570644.html

That's the state-of-the-art for cheap ones. Go 3X that price and they're pretty decent.

The EEVblog site is excellent for info about gear like this.

Also, the 4-channel version of the Siglent, the SDS1204X-E, can use either the built-in ethernet or a USB WiFi adapter, and has a built-in webserver which includes a mobile-optimized view.

EDIT: The new generation of DHO800/DHO900 Rigol scopes with touchscreens also have built-in web interfaces.