Open Hardware Board For Robust USB Power Monitoring

December 11, 2018 by Tom Nardi 9 Comments

We’ve all seen the little USB power meters that have become popular since nearly every portable device has adopted some variation of USB for charging. Placed between the power source and the device under test, they allow you to see voltage and current in real time. Perfect for determining how long you’ll be able to run a USB powered device on batteries, or finding out if a USB power supply has enough current to do the business.

[Jonas Persson] liked the idea of these cheap little gadgets, but wanted something a bit more scientific. His design, which he refers to as UPM, is essentially a “smart” version of those ubiquitous USB gadgets. Instead of just showing the data on a little LCD screen, it can now be viewed on the computer and analyzed. His little gadget even allows you to cut power to the device under test, potentially allowing for automated testing of things such as inrush current.

Essentially the UPM works in much the same way as the simple USB meters: one side of the device goes towards the upstream power source, and the device under test plugs into the other side. Between the two devices is a 16 bit ADC and differential amplifier which measures the voltage and current. There’s a header on the board which connects to the ADC if you wanted to connect the UPM to an external microcontroller or other data logging device.

But most likely you would be using the internal microcontroller to analyze the output of the ADC over I2C, which [Jonas] very cleverly connected to the upstream port with an integrated USB hub. One side of the hub goes off to the device being tested, and the other to the microcontroller. So the host device will see both the UPM’s integrated microcontroller and the target device at the same time. From there, you can use the ncurses user interface to monitor and control the device in real-time.

While the hardware looks more or less finished, [Jonas] has some more plans for the software side of UPM, including support for remote control and monitoring over TCP/IP as well as robust logging capabilities. This is definitely a very interesting project, and we’re excited to see it develop further.

In the past we’ve seen homebrew USB power meter builds, and even commercial offerings which boasted computer-based logging and analysis, so it was only a matter of time before somebody combined them into one.

Modified F Clamp Is Wheely Good

December 11, 2018 by Lewin Day 18 Comments

Sometimes, a job is heavy, messy, or unwieldy, and having an extra pair of hands to help out makes the job more than twice as easy. However, help isn’t always easy to find. Faced with this problem, [create] came up with an ingenious solution to help move long and heavy objects without outside assistance.

The build starts with a regular F-clamp – a familiar tool to the home woodworker. The clamp is old and worn, making it the perfect candidate for some experimentation. First off, the handle is given a good sanding to avoid the likelihood of painful splinters. Then, the top bar is drilled and tapped, and some threaded rod fitted to act as an axle. A polyurethane wheel from a children’s scooter is then fitted, and held in place with a dome nut.

The final product is a wheel that can be clamped to just about anything, making it easier to move. [create] demonstrates using the wheelclamp to move a long piece of lumber, but we fully expect to see these on the shelf of Home Depot in 12 months for moving furniture around the house. With a few modifications to avoid marring furniture, these clamps could be a removalist’s dream.

While you’re busy hacking your tools, check out these useful bar clamps, too. Video after the break.

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Fan-Based Parts Tumbler Is A Breeze To Build

December 6, 2018 by Kristina Panos 53 Comments

A parts tumbler is a great tool to have around. But if you don’t use it all the time, it’s hard to justify dropping hundreds of dollars on one. Fortunately, there are many ways to make your own tumbler while tailoring it to meet the need. Because really, as long as you get the medium moving enough to abrade the parts, you’re good.

[Daniele]’s parts tumbler is cool because it’s fairly easy to make, it’s really quiet, and it does the job quickly. This tumbler moves the medium by using an imbalanced plastic fan, which [Daniele] created by drilling a hole through one of the blades and fastening a short bolt and nut through it. If you’ve ever tried to stop a washing machine from walking away, you may be thinking this is a strange idea, because now he’s got a 4500 RPM vibration machine scuttling about the shop. So really, the true genius of this build lies in the great pains [Daniele] took to absorb all that vibration.

He’s got the fan float-mounted on rubber-lined springs and rubber mats under the washers involved in connecting the latching plastic box to the fan. Our favorite anti-vibration features are the twist-lock power connector and the custom silicone feet made from Motorsil D and cap bolts. We don’t know what the medium is here, but it’s got us thinking Grape-Nuts might work. Blow past the break to chew on the build video.

The only problem with this build is that this type of fan isn’t cheap, and using it this way will definitely shorten its life.

Not a fan of this type of tumbling? Here’s one that takes your drill for a spin.

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A Christmas Tree For Your Lab

December 6, 2018 by Al Williams 12 Comments

It seems like holiday decorations come up earlier and earlier every year. You might not have room for a full-blown tree in your lab, but if you have an arbitrary waveform generator and a scope, Tektronix has a way for you to show your spirit electronically.

You can see the video below. Naturally, it features Tektronix gear, but we are pretty sure you could make it work with any arbitrary waveform generator that has at least two channels and a scope with an XY mode.

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Adorable Desktop Disc Sander Warms Our Hearts And Our Parts

December 4, 2018 by Kerry Scharfglass 17 Comments

Casually browsing YouTube for “shop improvements” yields a veritable river of project ideas, objects for cat amusement, and 12 INCREDIBLE SHOP HACKS YOU WON’T BELIEVE, though some of these are of predictably dubious value. So you might imagine that when we found [Henrique]’s adorable disc sander we dismissed it out of hand, how useful could such a tiny tool be? But then we remembered the jumbo tub o’ motors on the shelf and reconsidered, maybe a palm sized sander has a place in the tiny shop.

Electrically the build is a simple as can be. It’s just a brushed DC motor plugged into a wall wart with a barrel jack and a toggle switch. But what else does it need? This isn’t a precision machine tool, so applying the “make it out of whatever scrap” mindset seems like a much better fit than figuring out PWM control with a MOSFET and a microcontroller.

There are a couple of neat tricks in the build here. The most obvious is the classic laser-cut living hinge that we love so much. [Henrique] mentions that he buys MDF in 3 mm sheets for easy storage, so each section of the frame is built from layers that he laminates with glue himself. This trades precision and adds steps, but also give him a little flexibility. It’s certainly easier to add layers of thin stock together than it would be to carve out thicker pieces. Using the laser to precisely cut holes which are then match drilled through into the rest of the frame is a nice build acceleration too. The only improvement we can imagine would be using a shaft with a small finger chuck (like a Dremel) so it could use standard rotary tool bits to avoid making sanding disks by hand.

What could a tool like this be used for? There are lots of parts with small enough features to be cleaned up by such a small tool. Perhaps those nasty burrs after cutting off a bolt? Or trimming down mousebites on the edges of PCBs? (Though make sure to use proper respiration for cutting fiberglass!)

If you want to make one of these tools for your own desk, the files are here on Thingiverse. And check out the video overview after the break.

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Keep Both Hands On The Probes With This Oscilloscope Footswitch

December 2, 2018 by Dan Maloney 18 Comments

We’ve got two hands, so it’s natural to want to use both of them while diagnosing a circuit with an oscilloscope. Trouble is, keeping both hands on the probes makes it a touch difficult to manipulate the scope. If only there were some way to put your idle lower appendages to work.

This multipurpose oscilloscope footswitch interface makes so much sense that we wonder why such a thing isn’t standard equipment on more scopes. [Paul Roukema]’s interface relies on the USB Test and Measurement Class (USBTMC) protocol that allows most modern scopes to be remotely controlled, somewhat like the General Purpose Interface Bus (GPIB) protocol of old. [Paul]’s interface uses an STM32 microcontroller to talk USBTMC to either Keysight’s Infinium scopes or the Tektronix DPO line, since those were what he had to test against. Tapping the footswitch cycles the acquisition mode on and off or triggers a single acquisition. He’s thoughtfully included the USBTMC specs in his GitHub project, so adapting it to other scopes should be straightforward. We’d even wager that older scopes with GPIB could enjoy the same handsfree control.

Have a down-market scope but still want to go handsfree? [Jenny List]’s primer on running a Rigol with Python might offer some hints on where to start.

CNC Machine Most Satisfyingly Mills Double-Sided PCBs

December 2, 2018 by Dan Maloney 50 Comments

We know that by this point in the development of CNC technology, nothing should amaze us. We’ve seen CNC machines perform feats of precision that shouldn’t be possible, whether it be milling a complex jet engine turbine blade or just squirting out hot plastic. But you’ve just got to watch this PCB milling CNC machine go through its paces!

The machine is from an outfit called WEGSTR, based in the Czech Republic. While it appears to be optimized for PCB milling and drilling, the company also shows it milling metals, wood, plastic, and even glass. The first video below shows the machine milling 0.1 mm traces in FR4; the scale of the operation only becomes apparent when a gigantic toothbrush enters the frame to clear away a little swarf. As if that weren’t enough, the machine then cuts traces on the other side of the board; vias created by filling drilled holes with copper rivets and peening them over with a mandrel and a few light hammer taps connect the two sides.

Prefer your boards with solder resist and silkscreening? Not a problem, at least judging by the second video, which shows a finished board getting coated with UV-cure resist and then having the machine mill away just the resist on the solder pads. We’re not sure how they deal with variations in board thickness or warping, but they sure have it dialed in. Regardless of how they optimized the process, it’s a pleasure to watch.

At about $2,600, these are not cheap machines, but they may make sense for someone needing high-quality boards with rapid turnaround. And who’s to say a DIY machine couldn’t do as good a job? We’ve seen plenty of them before, and covered the pros and cons of etching versus milling too.

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