One of the core features of the scientific community is the concept of “peer review” where any claims made by a scientist are open to be analyzed and reproduced by others in the community for independent verification. This leads to either rejection of ideas which can’t be reproduced, or strengthening of those ideas when they are. In this community we typically only feature the first step of this process, the original projects from various builders, but we don’t often see someone taking those instructions and “peer reviewing” someone’s build. This is one of those rare cases.
[oxullo] came across [Leo]’s original build for the ultimate continuity tester. This design is much more sensitive than the function which is built in to most multi-meters, and when building this tool specifically some other refinements can be built in as well. [oxullo] began by starting with the original designs, but made several small modifications. Most of these were changing to surface-mount parts, and switching some components for ones already available. Even then, there was still a mistake in the PCB which was eventually corrected. The case for this build is also 3D printed instead of being made out of metal, and with the original video to work from the rest fell into place easily.
[oxullo] is getting comparable results with this continuity tester, so we can officially say that this design is peer reviewed and tested to the highest of standards. If you’re in need of a more sensitive continuity sensor, or just don’t want to shell out for a Fluke meter when you don’t need the rest of its capabilities, this is the way to go. And don’t forget to check out our original write-up for this tester if you missed it the first time around.
Old lab equipment was often built to last, and can give decades of service when treated properly. It’s often so loved that when one part fails, it’s considered well worth repairing rather than replacing with something newer. [Michael] did just that, putting in the work to give his Fluke 8050A multimeter a shiny new display.
The Fluke 8050A is a versatile device, capable of measuring voltage, current, and resistance in addition to decibels at various impedences and conductance, too. The original display doesn’t show some of the finer details so well, so [Michael] elected to improve on that when he installed a new 2.2″ graphical LCD to replace the basic 7-segment LCD that originally came with the hardware.
To achieve the install, the original LCD display module was removed from the chassis. A piggyback device that sits under the Fluke’s microcontroller was then used to break out signals for the new graphical LCD without requiring modification to the meter’s PCB itself. An Atmega32u4 microcontroller then takes in these signals, and then drives the graphical LCD accordingly.
It seems like large-screen cheap meters are really catching on. [TheHWcave] does a very detailed review of a KAIWEETS KM601, which is exactly the same as a few dozen other Chinese brands you can get from the usual sources. You can see the review in the video below.
If we learned nothing else from this video, we did learn that you can identify unmarked fuses with a scale. The fuses inside were not marked, so he wanted to know if they appeared to be the right values. We would have been tempted to just blow them under controlled conditions, but we get he didn’t want to destroy the stock fuses until after testing.
There was a time when calculators became so powerful it was hard to tell them from little computers. The same thing seems to be happening now with multimeters. They now often have large screens and basic oscilloscope functionality. The specs keep getting better. While early cheap scopemeters were often relatively low frequency, many are now claiming bandwidths that would have cost quite a bit a few decades ago. A case in point is the Mustool MDS8207 which [IMSAI Guy] reviews and does a teardown of in the videos you can see below. It claims a 40 MHz bandwidth with 200 megasamples per second on a single channel.
The only downside in the claimed specifications is that the sensitivity isn’t great given that the lowest setting is 500 mV per division. Then again for a meter that runs under $100, any scope function would seem to be a bonus. The meter does all the other things you expect a meter to do these days, such as reading voltage, frequency, capacitors, temperature, etc. The response time of the meter is relatively slow, but you can get used to that.
Hackers are often of the sentimental type, falling in love with the look and feel of quality old hardware. Of course, sometimes that older hardware needs a little TLC to keep it running in the modern world. [Lex] had a beautiful vintage multimeter that sadly had a broken screen, and set about a nifty repair to restore it to working condition.
The HSN Avometer DA116 is a handsome thing, controlled with two dials and featuring a clean two-tone aesthetic. Even the font on the PCB’s silkscreen is gloriously pretty (can anyone ID that?). However, the original LCD was non-functional. A direct replacement part was sadly unavailable. Instead, to rectify this, [Lex] first hunted down another segmented LCD screen that had the same segment layout.
However, the new screen had a completely different pinout to the original part. Thus, after taking some notes and figuring out what all the pins did, [Lex] whipped up an adapter board to carry the new screen. With some protoboard, some pin headers, and a bunch of point-to-point wiring, the new screen worked just fine, and [Lex] had a functioning vintage meter once again!
Sadly, this particular model is especially subject to that exact vintage electronics issue: electrolytic capacitor failure and leakage. These failures can lead to destroyed traces, and this particular unit had a number of them (in addition to a few destroyed diodes, just for good measure.) That’s where the x-ray machine comes in handy, because some of the damage is hidden inside the multi-layer PCBs.
We’ve noticed lately that some cheap meters have gone to having big colorful screens. The screens aren’t dot matrix, but still have lots of graphics that could be useful or could be distracting eye candy, depending. The really cheap ones seem more like a gimmick, but [OM0ET] took a look at one that looked like a fair midrange instrument with some useful display features, the GVDA GD128.
A lot of the display shows the current function of the meter. No need for an expensive multiposition switch or rows of interlocking pushbuttons. Many of these new meters also have non-contact voltage sensors, which is handy. Otherwise, it looks like a pretty conventional cheap meter. Continue reading “Multimeters Go Big Screen”→