With the shopping cart I won in a project14 month, I ordered a handheld oscilloscope. In this post: my first impressions.
If you have an Owon HDS200 series instrument, you can follow along. It's the same. |
3 instruments in one
I have an MP720783 . A 70 MHz 2 channel oscilloscope, a DMM and function generator in a package that has the size and weight of a DMM. The 3 instruments can operate at the same time, but only one has the screen and buttons active at a time. You can use the function generator to serve an input test signal for your design, then use the oscilloscope and DMM to probe your design.
Overall look-and-feel is good. The buttons feel good and the display readability / clarity is good. Connections (except USB) are easy to get at. And there's a stable stand (if you dare to open it beyond the scary click position). I prefer to use the stand, because the reading angle is mediocre.
Overall first impressions are good, for all 3 modes. Using the instrument as a basic scope, generator or DMM is easy and intuitive. You can learn this in minutes, if you have previous experience.
Beyond that point, the interface gets more complex. The options are logical, not annoying and comparable to what other advanced instruments do. But at this point, the instrument is not as intuitive as a well designed bench instrument.
Being handheld, the instrument has an options that some bench instrument don't offer: (safe) isolation. The DMM is fully isolated, as expected. But also the oscilloscope and function generator aren't ground referenced. This can be an asset.
Be aware though, that the generator output and oscilloscope channel 1 + 2 grounds are common. And that both are also common with the USB connector shield. The instrument gives you safe options (CAT II) to do isolated probing. But you have to bring your brains to the party.
In the box:
- an x1/x10 probe (with the usual accessories) and 2 BNC-to-crocodile probes.
- rechargeable batteries
- USB cable for charging and interfacing, wall wart
- DMM probes
- a pouch
- manuals, software
Oscilloscope
This is the only relevant section you should care about. You'd get this instrument for its oscilloscope functions. |
Two channel, 70 MHz in my case - there is a 40 MHz version too. The usual channel options are available:
- probe x1 -> x10000
- AC / DC coupled, GND
- bandwidth 20 MHz / full
- time base from 10 ns to 500 s
- 10 mV to 10 V / div
- Sample and Peak Detect mode
- X/Y
Measure
- 7 measures (6 visible at a time across 2 channels), and a hardware counter
- cursors (CH1 or CH2 vertical, or time)
Trigger
- auto, normal, manual triggering and force
- rising / falling edge
- AC / DC coupled
Varia
- sample depth (4K / 8K)
- store wave form or screen print
- auto
Overall look, feel and use is easy. You get a common signal on the display as fast as you would with a bench instrument. Scaling and moving X and Y are a bit more involved.
It gets harder (compared to a bench instrument) when you want to zoom in to a part of a captured wave, or trigger on more advanced scenarios (there's no hold/delay or external trigger). The functions I use in my day-to-day probing are available.
Signals are clear on the display. The annotations on the screen are easy to read. Refresh rate OK.
Function Generator
This module is not available on all models. It has the usual signals: sinus, square, ramp. Up to 25 MHz for sinus, in the low MHz for the other waves. There's also a set of popular signals, called arbitrary. They are predefined, so that name is a bit odd.
There's one BNC output. You can set frequency, amplitude (+- 10 mV to 2.5 Vp/p), offset and impedance. The +- 2.5 V includes any DC offset applied. For some waveforms, there's a symmetry setting. It sets the duty cycle for pulse waves and skews the ramps for triangle wave. The rise / fall time of the pulse wave can be set too. The ground is shared with the oscilloscope and the USB connector.
Experience: It works. Definitely useable when you need a permanent test signal. The user interface of this module has seen less love than the scope. I don't see me using this on a regular base, except if I need one of the base waves quickly.
Arbitrary means that something is not predefined. This instrument says that it has arbitrary waveforms, but the ones served in that section are a known set of predefined waveforms. Your opinion may differ, but I would not call a fixed set of predefined waveforms arbitrary. I did not find an option in this instrument, under the arbitrary waveform menu, to define arbitrary waveforms. |
DMM
This option is available on all instruments of the series. A fully isolated DMM. The ground is not shared with scope, generator or USB. Specs are good, not spectacular. The 20000 count is the spec that stands out.
t's not difficult to use, but the user interface is different from how a DMM normally behaves.
There are also quirks e.g.:
- how auto / manual behaves in different modes,
- that it displays intermediate / way-off measurement values while it stabilises, without showing it's still stabilising (other meters show ---- or the likes)
The diode mode is good. I like the speed and latch of the continuity buzzer: just the right speed and stability to scratch over an IC and have beeps when there's contact.
Experience: works and will do the job. I do not like working with it though, because the interface is too different from what DMMs do. I believe this could be solved by having a UI engineer have a go at it.
Summary / verdict
This is a good product. The oscilloscope is a winner. An instrument that can have a main spot on the desk and in the toolbox. The two other options are useful, but I would never buy a separate handheld waveform generator or DMM that operates like these two options.
The unit sits good on the table, and using it with the probes is easy. A little bit too wide/rectangular for my hands to hold for a long time, but doable. The screen is clear inside and outside. A bit glary though, and scratch-prone.
end advice: Get it for the oscilloscope functionality. Take advantage of the two other options, but don't let them influence your purchase.