I have a fascination with the various online vendors of electronics and other manufactured goods from China. Here are listed the latest wonders from Shenzhen or wherever, which you can have for a surprisingly reasonable price, with the mild inconvenience of a three week wait for the postage.
A particular pastime of mine is to look for the bottom end of the market. Once I’ve picked up the items I came to order I’ll trawl around with the search with low price first and see what can be had for a few dollars. Yes, I take a delight in finding absolute trash, because just sometimes that way you can find a diamond in the rough.
So when I was shopping for a multimeter recently I took a quick look to see what the cheapest model from that particular supplier was. For somewhere around £2.50 or just over $3, I could have a little pocket analogue multimeter, the kind of “My first multimeter” that one might have found in the 1980s. They weren’t too bad, I thought, and ordered one for less than a pint of beer in a British pub.
If you fly much or work in a loud office, you know that noise-canceling headphones can be a sanity saver. Wouldn’t it be nice if you could just have noise-canceling without the headphones? Apparently, a lot of people think that’s a good idea and funded a project called Muzo. [Electroboom] borrowed one and — mystified how such a device could work — set out to test it. Along the way, in the video below, you can see him do a neat demonstration with two speakers canceling each other in his closet.
Based on [Electroboom’s] tests and the tests from other users, it doesn’t appear that Muzo does much to reduce noise. It might add some noise of its own, but that’s a far cry from what people expected the unit to do.
When men were men, and oscilloscopes were oscillographs.
Do you remember your first oscilloscope? Maybe we have entered the era in which younger readers think of a sleek model with an LCD screen, but for the slightly older among us the image that will come to mind is likely to be a CRT-based behemoth. Mine was a 2MHz bandwidth Cossor from the 1950s, wildly outdated by the 1980s, but it came to me at no cost. It proudly proclaims itself as a “Portable Oscillograph”, but requires its owner to be a weightlifter to move it. I still have it, as a relic and curio.
For most of us a new ‘scope is still a significant investment. Even affordable current models such as the extremely popular Rigol instruments are likely to cost several hundred dollars, but offer measurement functions undreamed of by those 1950s engineers who would have looked on the Cossor as an object of desire.
Oscilloscope buyers on a budget may not have the cash for a Rigol, a Hantek, or any of the other affordable ‘scopes. Someone starting on the road of electronic engineering can scout around for a cheap or free second-hand CRT model, but thanks to the ever advancing march of technology they also have another option. Modern microprocessors and microcontrollers have analogue-to-digital converters and processor cores that are fast enough to provide the functions of a simple oscilloscope, and to that end a variety of very cheap ‘scopes and ‘scope kits have come on the market. These invariably have a rather small LCD screen and a relatively low bandwidth, but since they can be had for almost pocket-money prices their shortcomings can be overlooked in the name of value. It’s been a matter of curiosity for some time then: are these instruments any good? For around £16 ($21) and the minor effort of an online order from China, we decided to find out.
If you look at most stockists of electronic kits these days, you are likely to find an oscilloscope kit in their range. These are volume produced in China, and the same design trends appear across different models. You can buy surface mount or through-hole, and most of them feature a bare board with maybe a piece of laser-cut Perspex standing in for a case. There are one or two models appearing that come with a case though, and it was one of these that we ordered. The JYE Tech DSO150 is a single-channel ‘scope with a 2.4″ 320×240 pixel colour LCD screen and a 200kHz bandwidth. Its specification is typical of the crop of similar kits, though its smart case sets it apart and made it an easy choice.
In the Box
We ordered one, and when it arrived, it was packed in a small cardboard carton that had suffered some crushing in transit, but had protected the internal contents well enough that no harm had been done. A layer of foam protected the LCD, and the case parts appeared rigid enough to protect the rest of the components. There was a bag of discretes, the case parts, two PCBs, a test lead with crocodile clips, and two pages of instructions.
When looking at a kit, it’s best to start with the instructions, because no matter the quality of the kit itself it is the quality of the instructions that make or break a kit. If you can’t build it then it doesn’t matter how good it might be, it’s effectively junk.
The DSO150 instructions are two sheets of high quality double-sided colour print, with the emphasis on pictures rather than words, The front page introduces the kit and gives a quick soldering guide, then the next two pages step through each stage of construction. The final page has basic instructions for use, specification, and a troubleshooting guide. Our kit had all surface-mount parts already fitted, if we’d known the kit could also be had with SMD parts to fit we’d have bought that version instead.
Inside the DSO100.
The instruction steps are long on images and short on text, but there are sometimes few cues as to where the component in question lies on the board. Sometimes some careful examination of board and picture is necessary to ensure correct placement. The first step though doesn’t involve any soldering, wire the main board up to a 9V supply, and watch the LCD boot into the oscilloscope software. There is support via a forum on the JYE Tech website, we presume you’d go there if it failed to boot out of the box. A 9V PSU isn’t included, you’ll need to find one with a 2.1mm centre positive plug. Fortunately a suitable candidate was in the box of wall warts here, formerly being used by a router.
The main board assembly is straightforward enough, being the assembly of larger through-hole parts such as switches and connectors. The analogue board has a brace of small through-hole resistors and ceramic capacitors to fit, of these the resistors were of the tiny variety which made distinguishing between some of their colour stripes a little difficult. Bring your multimeter to check. There is a BNC connector that requires significant heat on there too, so make sure you have a suitably beefy iron to hand. Finally there is a small board for the rotary encoder, then the front of the case can be assembled to the main board, the analogue board attached, and the ‘scope set up. Verify on-board voltages, attach the test clip to the calibration output and adjust the compensation capacitors for a square wave, and the rest of the case can be added to complete the unit.
Functionality
The DSO150 showing the upper end of its bandwidth.
In use, the DSO150 makes a simple and straightforward enough oscilloscope. The usual volts/division and timebase selection is easy enough, and the various trigger modes can quickly be selected. If you’ve used an oscilloscope before then you will have no problems getting started with it. But of course, the DSO150 isn’t just a simple oscilloscope, it’s a digital storage ‘scope. And with 1024 sampling points it can do the usual storage ‘scope thing of allowing the user to examine a stored waveform in great detail, scrolling back and forth through the stored points. Here the instruction sheet falls short, not mentioning that a double tap on the V/div or Sec/div buttons allows you to scroll.
Connecting the signal generator to our DSO150 allowed the exploration of its bandwidth. The claimed 200kHz is pretty spot-on, winding the signal generator far beyond that point showed a tail-off in displayed amplitude. Also the minimum 10µS per division limits the usefulness of a waveform display at these frequencies.
The DSO150 is supplied with a short test lead terminated in a pair of crocodile clips. This is somewhat less useful than the oscilloscope probes we’re used to, though happily it can also be used with a standard 1x/10x probe. Looking at the square wave on the test terminal through a standard probe reveals a sharp corner on the waveform, so there seems not to be any problems between the compensation on-board and that in the probe. It’s likely that either the DSO150 here will be used with a standard probe, or that the crocodile clip will swiftly be replaced with a probe of some kind.
Closing Thoughts
So then, the JYE Tech DSO150 oscilloscope kit. A nice little ‘scope within the limitations of the STM32F103C8 microcontroller that drives it. If you can put up with a 200kHz bandwidth and a 50V peak input voltage then it’s a useful pocket instrument. Its calibration will depend on the STM’s crystal and voltage reference, but as with the rest of its specification, when you consider its pocket-money price those become minor considerations. Add in that its software is open-source, and you have a very nice platform indeed. If we wanted to nitpick we’d ask for a battery compartment and a proper probe, but since both of those would put up the price we wouldn’t make too much noise about it. If you need a pocket ‘scope to supplement your bench scope when working on lower frequencies, or if you have a youngster in the family looking for their first ‘scope, buy one! Our review unit will definitely see some use rather than gathering dust.
If you were to ask a random Hackaday reader what their most fundamental piece of electronic test equipment was, it’s likely that they would respond with “multimeter”. If you asked them to produce it, out would come a familiar item, a handheld brick with a 7-segment LCD at the top, a chunky rotary selector switch, and a pair of test probes. They can be had with varying quality and features for anything from a few dollars to a few hundred dollars, though they will nearly all share the same basic set of capabilities. Voltage in both AC and DC, DC current, resistance from ohms to mega ohms, and maybe a continuity tester. More expensive models have more features, may be autoranging, and will certainly have better electrical safety than the cheaper ones, but by and large they are a pretty standard item.
If Hackaday had been around forty years ago and you’d asked the same question, you’d have had a completely different set of multimeters pulled out for your inspection. Probably still a handheld brick with the big selector switch, but instead of that LCD you’d have seen a large moving-coil meter with a selection of scales for the different ranges. It would have done substantially the same job as the digital equivalent from today, but in those intervening decades it’s a piece of equipment that’s largely gone. So today I’m going to investigate moving coil multimeters, why you see them a lot less these days than you used to, and why you should still consider having one in your armoury. Continue reading “Why You Shouldn’t Quite Forget The Moving Coil Multimeter”→
For the last few months, I had been using Sparkfun’s Phant server as a data logger for a small science project. Unfortunately, they’ve had some serious technical issues and have discontinued the service. Phant was good while it lasted: it was easy to use, free, and allowed me to download the data in a CSV format. It shared data with analog.io, which at the time was a good solution for data visualization.
While I could continue using Phant since it is an open-source project and Sparkfun kindly releases the source code for the server on Github, I thought it might be better to do some research, see what’s out there. I decided to write a minimal implementation for each platform as an interesting way to get a feel for each. To that end, I connected a DHT11 temperature/humidity sensor to a NodeMCU board to act as a simple data source.
The mid-1980s were a time of drastic change. In the United States, the Reagan era was winding down, the Cold War was heating up, and the IBM PC was the newest of newnesses. The comparatively few wires stitching together the larger university research centers around the world pulsed with a new heartbeat — the Internet Protocol (IP) — and while the World Wide Web was still a decade or so away, The Internet was a real place for a growing number of computer-savvy explorers and adventurers, ready to set sail on the virtual sea to explore and exploit this new frontier.
In 1986, having recently lost his research grant, astronomer Clifford Stoll was made a computer system admin with the wave of a hand by the management of Lawrence Berkeley Laboratory’s physics department. Commanded to go forth and administer, Stoll dove into what appeared to be a simple task for his first day on the job: investigating a 75-cent error in the computer account time charges. Little did he know that this six-bit overcharge would take over his life for the next six months and have this self-proclaimed Berkeley hippie rubbing shoulders with the FBI, the CIA, the NSA, and the German Bundeskriminalamt, all in pursuit of the source: a nest of black-hat hackers and a tangled web of international espionage.
In July we reported on the launch of the Hologram developer program that offered a free SIM card and a small amount of monthly cellular data for those who wanted to build connectivity into their prototypes. Today, Hologram has launched some new hardware to go along with that program.
Nova is a cellular modem in a USB thumb drive form factor. It ships in a little box with a PCB that hosts the u-blox cellular module, two different antennas, a plastic enclosure, and a SIM card. The product is aimed at those building connected devices around single-board computers, making it easy to plug Nova in and get connected quickly.
This device that Hologram sent me is a 3G modem. They have something like 1,000 of them available to ship starting today, but what I find really exciting is that there is another flavor of Nova that looks the same but hosts a Cat-M1 version of the u-blox module. This is a Low Power Wide Area Network technology built on the LTE network. We’ve seen 2G and 3G modems available for some time now, but if go that route you’re building a product around a network which has an end-of-life concern.
Cat-M1 will be around for much longer and it is designed to be low power and utilizes a narrower bandwidth for less radio-on time. I asked Hologram for some power comparison estimates between the two technologies:
AVERAGE current consumption comparisons:
Cat-M1: as low as 100 mA while transmitting and never more than 190 mA
Equivalent 3G: as high as 680 mA while transmitting
PEAK current consumption comparisons (these are typically filtered through capacitors so the power supply doesn’t ever witness these values, and they are only momentary):
Cat-M1: Less than 490 mA
Equivalent 3G: As high as 1550 mA
This is an exciting development because we haven’t yet seen LTE radios available for devices — of course there are hotspots but those are certainly not optimized for low power or inclusion in a product. But if you know your ESP8266 WiFi specs you know that those figures above put Cat-M1 on a similar power budget and in the realm of battery-operated devices.
The Cat-M1 Nova can be ordered beginning today, should ship in limited quantities within weeks, with wider availability by the end of the year. If you can’t get one in the first wave, the 3G Nova is a direct stand-in from the software side of things.
I suspect we’ll see a lot of interest in Cat-M1 technology moving forward simply because of the the technology promises lower power and longer support. (I’m trying to avoid using the term IoT… oops, there it is.) For today, let’s take a look at the 3G version of the new hardware and the service that supports it.
If you look at most stockists of electronic kits these days, you are likely to find an oscilloscope kit in their range. These are volume produced in China, and the same design trends appear across different models. You can buy surface mount or through-hole, and most of them feature a bare board with maybe a piece of laser-cut Perspex standing in for a case. There are one or two models appearing that come with a case though, and it was one of these that we ordered. 
