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Friday, September 16. 2011
For some time, I had been contemplating the purchase of a pocket oscilloscope for up-the-tower or car fixing work. A few months ago I came across this oscilloscope listing on eBay. It was from a Canadian seller called "nooelec". The unit is a JYE DSO 082. It is a single channel, 10MHz bandwidth, 50Ms/S sample rate, LCD display digital storage oscilloscope. The specifications looked promising, so I went ahead and ordered one.
In preparation for this review, you may want to learn more about the unit on the manufacturer's website. The user manual is available there. There are a couple of videos as well.
My first impression upon opening the box was that this is a nice lightweight portable unit. The plastic enclosure looks well made. And there is a foldable stand on the back of the unit that can be deployed to position the unit facing the user when working on a bench, a nice feature. The rubber push-buttons and the rotary encoder appear to be of decent quality. I am not so sure about the slide switches though. Will they survive years of action? The supplied probe looks like a good copy of an HP probe and it does the job. The LCD screen is a green backlit unit, not a blue unit like pictured on the JYE website and in the user manual. It is bright and crisp, better than I would have thought considering its size. And its size is OK, but those who wear glasses to read will need them here. Here is one final note on the display. The user manual claims that the contrast is adjustable, but I could not find an external contrast adjustment described in the manual. I could not find any menu either that accomplished that. If you do, let me know. I believe there is a small potentiometer inside the enclosure, but I will not open up the unit at the risk of voiding the one-year warranty. So I am stuck with the current contrast setting for now. Why advertize it then?
The unit is small enough to be carried around and to the outdoors for car fixing and such, but it lacks a battery. So one will have to carry a 9-12V battery around with the scope. By the way, the unit gets quite warm to the touch, which means that there is a lot of energy wasted in heat, that is at least when using the AC adapter.
Now on to the performance! The first thing I did was to hook up the probe and play with probe compensation. The test signal is sharp and square, a good thing to help adjust probe compensation. But the probe was already compensated. I tried to adjust the probe compensation capacitor, but nothing happened... the probe remained properly compensated. Hmmmm...defective probe? I'll probably try out another probe when I get a chance.
The CPU inside the unit has no problem keeping up with the tasks. This manifests itself in a fast screen refresh rate and immediate button responsiveness; the screen refresh rate is fast enough to make it look like one of an analog scope. Of course, this is only applicable for time resolutions of less than around 50ms/div.
I verified that the analog bandwidth is of more than 10MHz, as described in the manual. But the unit starts to seriously distort the signal at around a 10MHz frequency due to the lack of samples. Moreover, a 10MHz periodic signal is way too much compressed on the horizontal scale with the 200ns/div minimum time resolution. A 100ns/div setting would have helped here. Consequently, the 10MHz bandwidth is useful to analyze the rising/falling edges of a long pulse, but is pretty much useless for repetitive signals in that range of frequencies.
Lower frequency repetitive un-modulated signals (sine, square, etc) looked sharp, solid and of good amplitude accuracy. The same could be said of one shot pulses. The trigger features (internal/external, normal, automatic, single) are versatile enough to do the basic work we expect from a sampling scope. The zoom-in feature, which allows you to zoom in by several time/div steps to a captured waveform, is a nice surprise. As expected, the units had problems dealing with the trigger and display of modulated signals. Note that my 500MHz - 2GS/s HP 54542A also struggles at this. Good old analog scopes shine when it comes to displaying modulation envelopes.
By far, the most missing features are marker/cursor measurements and waveform measurement functions. Other than counting the grids and dots, there is no way to measure the amplitude and period of a signal, or the amplitude and time between two points. This brings us back to the analog scope era. I understand this would grow the firmware size a lot. But I think a simple double-cursor feature could be implemented relatively easily. Let's hope there will be improved firmware in the future.
The FFT function is an intriguing addition but it has limited use. The frequency axis is calibrated and appears to be accurate (to the extent of its limited resolution). You cannot scroll horizontally though, in other words the displayed spectrum always starts at zero Hertz. Also, there is no amplitude scale! So you can see the presence of various frequency components but cannot estimate their relative amplitude. That is the big limitation in FFT mode. And once again, no cursors to estimate the frequency or amplitude.
I have not tried to download screen captures to a PC, but I have every reason to believe that it would work. It uses the standard and much used USB-to-Serial conversion scheme, so it ought to work.
All in all, and considering its price, the JYE DSO 082 oscilloscope is a useful, well built unit for general troubleshooting activities. It does not match the capabilities of bigger more expensive units, but that was expected. The fact that is has only one input channel also limits its versatility. Nevertheless, it brings in the benefits of a scope and is much better than a logic probe or a voltmeter when it comes to, for example, logic circuit development and debugging. To summarize it in one statement, I like it and will keep it.
Please add your comments and experience with this device.
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I don't own this particular oscilloscope but I do own several other JYEtech products including a capacitance meter kit I built last night- which cost $11- seriously, $11 - and it has a digital readout and serial output capabilities. (if you want to use it with TTL or RS232 you need a 3.3 volt to whatever level shifter) Ive verified it as being accurate- it will read capacitance down to .1 pf I dont know how accurate it can be that low, but the capacitors I tested all appeared to be measured accurately. A lot of people like to denigrate Chinese companies and -some asian electronics companies don't make the best quality products its true. But JYEtech's products are an EXCEPTIONAL value and I am 100% certain that five years from now I will still be using every single device I have of theirs, which were all quite affordable.
By the way, they also often release updated firmware for past models. One of their recent scopes similar to yours is now also able to act as a USB scope.. I think it is the 95, not the 82, but you might want to check..