These days, if you are in the market for a capable digital voltmeter, you might as well consider getting one with an oscilloscope built-in. One choice is the Owon HDS160, which [Kerry Wong] covers in the video below. The model is very similar to the HDS120, but the multimeter in the HDS160 has more counts–60,000 vs 20,000 as you might expect from the model number.
The internal chip is an HY3131, which is rated at 50,000 counts which is odd since the meter is 60,000 counts, but presumably the meter uses some capability of the chip, possibly putting it out of spec. The oscilloscope is the same between the two models. Almost everything else works the same, other than the capacitance measuring feature, as the video shows.
The difference in cost between the two units isn’t much, so if you are shopping, the small extra cost is probably worth it. Not that a 20,000 count meter isn’t perfectly fine for most normal uses.
We’ve all seen those cheap bench power supply units (PSUs) for sale online, promising specifications that would cost at least a hundred dollars or more if it were a name brand model. Just how much of a compromise are these (usually rebranded) PSUs, and should you trust them with your electronics? Recently [Denki Otaku] purchased a cheap unit off Amazon Japan for a closer look, and found it to be rather lacking.
Internals of the cheap bench PSU reviewed by Denki Otaku on YouTube.
Major compromises include the lack of an output power switch, no way to check the set current limit without shorting the output, very slow drop in output voltage while adjusting due to the lack of a discharge circuit, and other usability concerns. That’s when the electrical performance of the PSU got tested.
Right off the bat a major issue in this cheap switching mode PSU is clear, as it has 200 mV peak-to-peak noise on its output, meaning very little output filtering. The maximum power output rating was also far too optimistic, with a large voltage drop observed. Despite this, it generally worked well, and the internals – with a big aluminium plate as heatsink – look pretty clean with an interesting architecture.
The general advice is to get a bench PSU that has features like an output power button and an easy way to set the voltage and current limits. Also do not connect it to anything that cares about noise and ripple unless you know that it produces clean, filtered output voltages.
If you’re into electronics you can never have too many digital multimeters (DMMs). They all have different features, and if you want to make multiple measurements simultaneously, it can pay to have a few. Over on his video blog [joe smith] reviews the new Brymen BM788BT, which is a new entry into the Bluetooth logging meter category.
According to a post on the EEVblog, this Bluetooth variant was promised five years ago, and back then Brymen even had the Bluetooth module pin header on the PCB, but it has taken a long time to get the feature right. If you scroll through the thread you will find that Brymen has made its protocol specification available for the BM780 series meters.
It looks like some Bluetooth hacking might be required to get the best out of this meter. Of course we’re no strangers to hacking DMMs around here. We’ve taken on the Fluke 77 for example, and these DMM tweezers.
Current measurements are not as handy as voltage measurements. You typically need to either measure the voltage across something and do some math or break the circuit so a known resistor in your instrument develops a voltage your meter measures and converts for you. However, it is possible to get non-contact current probes. They are generally pricey, but [Kerry Wong] shows us one under $200 and, thus, budget compared to similar probes. Check out the review in the video below.
The OWON unit has three ranges: 4 A, 40 A, and 400 A. It claims a resolution of 10 mA and a bandwidth of 200 kHz. It requires a 9 V battery, which [Kerry] suspects won’t last very long given the rated power consumption number, although the measured draw was not as high as claimed. The specs aren’t great — this seems to be little more than a current probe meter with a connector for an oscilloscope, but if it meets your needs, that could be acceptable.
[Project Farm] has a video in which a wide variety of AA cells are analyzed and compared in terms of capacity, internal resistance, ability to deliver voltage under load, and ability to perform in sub-freezing temperatures. Alkaline, lithium, and even some mature rechargeable cells with a couple thousand cycles under their belt were all compared. There are a few interesting results that will can help you get the most from your money the next time you’re battery shopping.
The video embedded below demonstrates a set of tests that we recommend you check out, but the short version is that more expensive (non-rechargeable) lithium cells outperform their alkaline peers, especially when it comes to overall longevity, ability to perform under high-drain conditions, and low temperatures. Lithium cells also cost more, but they’re the right choice for some applications.
Some brands performed better and others worse, but outside of a couple stinkers most were more or less comparable. Price however, was not.
As for how different brands stack up against one another, many of them are more or less in the same ballpark when it comes to performance. Certainly there are better and worse performers, but outside of a couple of stinkers the rest measure up reasonably well. Another interesting finding was that among rechargeable cells that were all several years (and roughly 2,200 charge-discharge cycles) old, a good number of them still performed like new.
Probably the single most striking difference among the different cells is cost — and we’re not just talking about whether lithium versus alkaline AAs are more cost-effective in the long run. Some brands simply cost twice as much (or more!) than others with comparable performance. If you’re in a hurry, jump to [Project Farm] presenting the final ranked results at 19:45 in.
Relying on brand recognition may save you from buying complete junk, but it’s clearly not the most cost-effective way to go about buying batteries. These findings are similar to an earlier effort at wide-scale battery testing which also determined that factoring in price-per-cell was too significant to ignore.
There aren’t many people who could do an hour-long video reviewing an oscilloscope, but [Kerry Wong] is definitely one of them. This time, he’s looking at a UNI-T MSO2304X 300 MHz scope. The review might be a little long, but the scope — like many modern scopes — has a lot of features for measuring power, accommodating digital signals with an add-on pod, and protocol decoding.
The scope has a touchscreen and four normal inputs, plus two frequency generator outputs. You can also use a mouse or an external display. But, of course, what you really want to know is how the scope performs when reading signals.
[Maker’s Fun Duck] has a recent video review of a cheap thermal camera from a company called Kaiweets, which you can see below. It checked all of his boxes: It was standalone, handheld, cheap, and not too cheap. The question is: does it work well for the kinds of things we would do with such a camera?
That’s a tricky question, of course, because everyone’s uses are different. Considering a soldering iron. A tiny one is great for working on PCBs, but lousy for soldering large coax connectors. A soldering gun works well for that purpose, but is too much for the PCB. The same goes for thermal cameras. Some are great for, for example, finding leaky parts of houses, but might not be so great at locating defective components on a PCB.
