Velleman WFS210 wireless oscilloscope for only £20 !

[jimmc101]

Another bargain I couldn't resist.   Credit to Fraser on the EEVblog forum for spotting this.

An interesting 'scope that uses a PC / Android / IOS device as the display.
Connection is wireless and it's powered by a rechargeable battery so it should be great for floating measurements.
Not the latest and greatest but for £20...


Specifications

- Input range: 5mV to 20V/div (12 steps)
- Timebase: 1µs to 1s/div
- Max. 30Vpp input
- Real time sample rate: 2 x 10MS/s
- Input impedance: 1Mohm
- Input coupling: AC+DC, AC and GND
- Bandwith: 2 x 10MHz
- AD resolution: 8 bit
- Sample buffer: 4K/channel
- Consumption (battery): 160mA (max.)
- Battery: Li-ion 3.7V 1800mAh
- USB charge current: 5V/500mA
- Max. weight: 180g (0,39lb)
- Dimensions: 100 x 100 x 35mm / 3.9 x 3.9 x 1.4”


Minimum system requirements
iOS (*)
Android™ 4.0 (*)
Windows XP or higher (*)
Tablet or PC

Jim

[ppppenguin]

I can see this being useful in floating applications. Still need to be very careful about using both channels as they share a common "earth". Also be very wary of using it on live mains, just as you would be when using a cheap DMM

[Mark Hennessy]

The only potential downside is no support for Windows 8/10. But the upsides more than outweigh that, especially at that price! As you both say, great for floating measurements. The JYE kits can be useful for that sort of thing, but this has greater bandwidth and better functionality. For £20, what's to lose?

[Nick]

Bandwidth is never 10MHz - that's the sample rate.

With basic Nyquist the bandwidth would be 5MHz but more realistically is likely to be around 2.5MHz.

[ppppenguin]

Well spotted, Nick. Specs probably written in ignorance rather than maliciously.

[Nick]

Fraser, the guy that posted about these, reckons it's really only good to 1MHz.

Lots of problems with the firmware and client s/w, but the code is available on GitHub and there seems to be a hacker community around it, i.e. there is hope.

http://www.eevblog.com/forum/testgear/ve...msg1311234

[Mark Hennessy]

Bandwidth is never 10MHz - that's the sample rate.

With basic Nyquist the bandwidth would be 5MHz but more realistically is likely to be around 2.5MHz.

Yet my Fluke PM3380A Combiscope has a 100MHz bandwidth, despite only being 100MS/s?

That's because of Equivalent-time sampling:

When a DSO uses equivalent-time sampling, it can acquire any signal up to the analog bandwidth of the scope regardless of the sample rate. In this mode, the scope gathers the necessary number of samples across several triggers. The input signal must be repetitive to generate the multiple triggers needed for equivalent-time sampling. In equivalent-time, a slower, lower-cost digitizer provides the same accuracy on repetitive waveforms as a higher cost DSO with a faster sampler. For example, the TDS 460 offers a 350 MHz bandwidth with only a 100 MS/s sampling rate on each of its four channels.

I can't comment on this unit specifically yet, but as it's quite possible it has equivalent-time sampling, I wouldn't jump to any conclusions until I've tested it. And even if the unit as supplied doesn't support equivalent-time sampling, it's possible that someone will add it to the software in the future.

Equivalent-time sampling obviously can't be used for single-shot mode - that's when the sample rate becomes a relevant. In other words, the sample rate is not a measure of bandwidth in the conventional Nyquist sense; rather it's a measure of signal fidelity when using real-time sampling mode.

[ppppenguin]

Equivalent time sampling predates digital scopes by a long time. For example the Tektronix 1S1 sampling plugin for the 500 series mainframes gave 1GHz BW at a very low sample rate. That was back in the 1960s. The front end has to have the BW and the sampler must be fast enough.

[jimmc101]

My 'scope arrived today, to say it has issues would be an understatement (see the EEVblog thread).
If it had been full price I wouldn't hesitate to send it back, for £20 I haven't made my mind up yet.

Jim

[ken]

My 'scope arrived today, to say it has issues would be an understatement (see the EEVblog thread).
If it had been full price I wouldn't hesitate to send it back, for £20 I haven't made my mind up yet.

Jim

Ah thats bad news. I too have ordered one which should arrive some time this week coming. I've downloaded the app for IOs. I also have an android 6.1 TV box. I thought of downloading the andriod app to try on this. I even have XP running with the sp4 updates antivirus and malwarebytes up to date. Don't tend to use it on web but I believe the firmware will run on this. Can I ask what your running it on.

Regards,

Ken.