Give your Multimeter a Wireless Remote Display

Multimeters are one of the key tools in a hardware hacker’s bench. For 90% of us, the meter leads are perfect for making measurements and looking over at the results. Sometimes you need a bit more distance though, and for that, [Ken Kaarvik] has created the Multimeter remote display. Remote displays are pretty handy when you want to measure something several feet away from your bench. They’re also great if you need to check something in an enclosed space, like a server rack or a refrigerator. Fluke actually sells multimeters with wireless displays, such as their model 233.

The key to this project is the FS9721 LP3 chip by Fortune Semiconductor. (PDF link) The FS9721 is essentially a system on chip (SOC) for multimeters. It contains a digital to analog to digital converter, an LCD driver, and a microcontroller. It also can send data out over a 2400 baud serial link. Two of [Ken’s] multimeters, the Digitek DT-4000ZC and a Fluke 17B, both have this chip. The Digitek has a 1/8″ plug for connecting to the outside world, while the Fluke requires some simple hardware mods to enable data output.

Since this was his entry for the Trinket EDC contest,  [Ken] connected the serial output of the FS9721 to an Adafruit Pro Trinket. The Trinket formats the data and sends it to an  nRF24L01+ 2.4GHz radio module. The receiving end has an identical radio, and another Pro Trinket. [Ken] actually built two wireless displays. One is a dual-boot Game Boy advance which has a really slick background on the color display. The other receiver utilizes a 128×64 OLED. The trinket, nRF24L01+ and display all fit neatly inside an Altoids tin.

Click past the break to see both wireless remote displays in action!

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Emergency Power Based on Cordless Drill Batteries

[Don Eduardo] took matters into his own hands after experiencing a days-long power outage at his house. And like most of us have done at least one, he managed to burn his fingers on a regulator in the process. That’s because he prototyped a way to use power tool batteries as an emergency source — basing his circuit on a 7812 linear regulator which got piping hot in no time flat.

His next autodidactic undertaking carried him into the realm of switch-mode buck converters (learn a bit about these if unfamiliar). The device steps down the ~18V output to 12V regulated for devices meant for automotive or marine. We really like see the different solutions he came up with for interfacing with the batteries which have a U-shaped prong with contacts on opposite sides.

The final iteration, which is pictured above, builds a house of cards on top of the buck converter. After regulating down to 12V he feeds the output into a “cigarette-lighter” style inverter to boost back to 110V AC. The hardware is housed inside of a scrapped charger for the batteries, with the appropriate 3-prong socket hanging out the back. We think it’s a nice touch to include LED feedback for the battery level.

We would like to hear your thoughts on this technique. Is there a better way that’s as easy and adaptive (you don’t have to alter the devices you’re powering) as this one?

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SPATA: shaving seconds and saving brainpower whilst 3D-modeling

If you’ve spent some late nights CADing your next model for the 3D printer, you might find yourself asking for a third hand: one for the part to-be-modeled, one for the tool to take measurements, and one to punch the numbers into the computer. Alas, medical technology just isn’t there yet. Luckily, [Christian] took a skeptical look at that third hand and managed to design it out of the workflow entirely. He’s developed a proof-of-concept tweak on conventional calipers that saves him time switching between tools while 3D modeling.

His build [PDF] is fairly straightforward: a high-resolution digital servo rests inside the bevel protractor while a motorized potentiometer, accelerometer, and µOLED display form the calipers. With these two augmented devices, [Christian] can do much more than take measurements. First, both tools are bidirectional; not only can they feed measurement data into the computer with the push of at button, both tools can also resize themselves to a dimension in the CAD program, giving the user a physical sense of how large or small their dimensions are. The calipers’ integrated accelerometer also permits the user to perform CAD model orientation adjustments for faster CAD work.

How much more efficient will these two tools make you? [Christian] performs the same modeling task twice: once with conventional calipers and once with his tools. When modeling with his augmented device, he performs a mere 6 context switches, whereas conventional calipers ratchet that number up to 23.

In a later clip, [Christian] demonstrates a design workflow that combines small rotations to the model while the model is sculpted on a tablet. This scenario may operate best for the “if-it-looks-right-it-is-right” sculpting mindset that we’d adopt while modeling with a program like Blender.

Of course, [Christian’s] calipers are just a demonstration model for a proof-of-concept, and the accuracy of these homemade calipers has a few more digits of precision before they can rival their cousin on your workbench. (But why let that stop you from modifying the real thing?) Nevertheless, his augmented workflow brings an elegance to 3D modeling that has a “clockwork-like” resonance of the seasoned musician performing their piece.

[via the Tangible, Embedded, and Embodied Interaction Conference]

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Parts.io Aims at Better Component Discovery

Online parts search and ordering is a godsend compared to the paper-catalog days of yore. This is fact, there is no argument otherwise (despite [Dave Jones’] assertion that sourcing connectors is so much simpler if you have pages full of images). Just being able to search was a game changer. But how far do you think the concept has come since the transition online? [Chris Gammell] plans to spark a leap forward with Parts.io, an electronic component info delivery system that spans both manufacturers and distributors.

So what’s wrong with what we’re doing now? Nothing… unless you hate wasting time. Sourcing parts is time consuming. Certainly the parametric search on distributors’ sites like Mouser and Digikey have improved. Plus we’ve seen hacks that do things like automatically pull in stock data to a spreadsheet. But the real issue isn’t figuring out how to buy stuff, it’s figuring out what to use in a design. Surely there is opportunity for improvement.

Parts.io has its sights set on a better path to part discovery. Yes, this is parametric search but it will return data for all parts from all manufacturers. The distinction may not be completely obvious, but for example if you are searching on Element14 you’re only getting data on the parts that Element14 carries. Once you have drilled down to a reasonably manageable pool of components you get what you would expect: one-click datasheets and a roundup of pricing and availability from worldwide distributors. The presentation of the parts is grouped into families that differ in trailing parts designators, and I must say I am impressed at the interface’s ability to roll with you. It feels easier to find alternative parts after the drilldown where in my past searches I would have started completely over again.

The service started in private alpha in October but is now available for public use. You can search for a part without logging in, but a few features have been held back for those that sign up for a free account. Most notably this includes the ability to upload your BOM, add parts as favorites, and access their forums.

Is this a game changer? That’s for you to decide. You can give it a try yourself or watch [Chris’] feature walkthrough video found after the break.

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A Low Cost Bench Supply

Everyone needs a power supply on their bench, but a standard lab supply isn’t cheap. [ludzinc]’s PSU Console is a cheap alternative, which provides the basic features you’d expect in a lab supply.

The basis of this PSU is a DC/DC module based on the LM2596 step down switching regulator. These modules cost less than a single LM2596, but have all the required components for a buck DC/DC converter. Sure, they might not last forever, and they’re not the most efficient regulators, but the price is right.

The front panel has four displays for voltage and current, which are just low cost voltmeter displays. The potentiometers are used for adjusting the voltage of the DC/DC, and controlling the current limiter. This limiter monitors current through a shunt, and shuts off a MOSFET when the limit is exceeded.

The final product looks like something that’s ready for daily use, and was much cheaper than most supplies with these features. These low cost DC/DC modules are worth a look if you’re considering a similar build.

Save Data from Old Scopes with a GPIB Disk Emulator

If you still use old test equipment on a regular basis, you probably have been frustrated by the lack of options for pulling data off these aging devices. Many higher-end devices are equipped with GPIB ports, which are general purpose buses for communicating with a variety of obsolete peripherals. Since GPIB disk drives aren’t too common (or practical) these days, [Anders] made a GPIB adapter that emulates a disk drive and stores data to an SD card.

[Anders] designed a PCB with a PIC microcontroller that plugs into a GPIB port. The PIC emulates a disk drive using the AMIGO protocol or the SS/80 protocol, which can be selected in a configuration file on the SD card. Most test equipment supports one of these two protocols, so his adapter should work with pretty much any GPIB-equipped kit.

Data is saved to a single image file on the SD card, which is encoded in a native HP disk format. The image file can be opened on Windows and Linux with some utilities that [Anders] mentioned on his project page. If you have any old test equipment withGPIB lying around and want to build your own, the schematic and source code are up on his site or [Anders] is selling bare boards.

Now if it’s a protocol converter that you need we’ve seen those in a couple of different varieties.

Sigzig data loggers ditch the noise while pimping the case

We ran into [Paul Allen] at CES. He was showing off Sigzig, a super-low noise data logger which his company is just rolling out.

IMG_20150107_174520A couple of years ago he worked on a standalone chemical sensor and had a few extra boards sitting around after the project was done. As any resourceful hacker will do, he reached for them as the closest and easiest solution when needing to log data as a quick test. It wasn’t for quite some time that he went back to try out commercially available loggers and found a problem in doing so.

The performance of off-the-shelf data loggers wasn’t doing it for [Paul’s] team. They kept having issues with the noise level found in the samples. Since he had been patching into the chemical sensor PCBs and getting better results, the impetus for a new product appeared.

The flagship 24-bit 8-channel Sigzig samples 0-5v with less than 1uV of noise. A less expensive 4-channel differential unit offers 18-bit with 10-12 uV of noise. They are targeting $199 and $399 price points for the two units. We asked about the sample rate in the video below. The smaller version shown here captures up to 240 samples per second. The big guy has the hardware potential to sample 30,000 times per second but since the data is continuously streaming over USB that rate is currently limited to much less.

Update: It has been pointed out in the comments that USB may not be the choke point for sample rate.