AppCAD Does Transmission Lines

July 20, 2021 by Al Williams 7 Comments

Broadcom and Agilent are perhaps not household words in every household, but among those who work with RF, they are common enough names. An Agilent developer wrote AppCAD to help with common RF design computations and now works for Avago who bought Broadcom. But whoever’s branding is on it, you can download the tool from Broadcom or check out the latest beta version. Then watch [IMASI Guy’s] video below on how to use part of it.

What can it do? According to the website:

S-Parameter Analysis and Plotting
Active Circuit Bias Design
Cascade Noise and IP3 Analysis
Transmission Line Analysis
Signals and Systems
Complex Math Engineering Calculator

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DeWalt Literal Hack Upgrades Battery

July 18, 2021 by Al Williams 40 Comments

There are several important decisions you make in your life: Coke or Pepsi; vi or emacs; PC or Mac. But, lately, you need to pick a battery ecosystem for your tools. DeWalt? Black & Decker? Or just cheapies from Harbor Freight? But what happens when your vendor of choice changes their batteries? That’s the situation [jleslie48] found when a DeWalt 14.4V battery died. All the new tools require 18V batteries, so buying an old battery for one tool didn’t make sense. Time to literally hack the old tool to accept the new battery.

Presumably, nothing in the drill will mind the higher voltage. It is all a matter of mechanics and nothing a Dremel tool won’t fix. Since the tool was old and the 18V batteries relatively new, [jleslie48] decided to limit modifications to the tool only leaving the batteries intact for use with the newer tools.

The only problem once you remove the pins and clips that interfere with the battery fit, it won’t actually stay on the drill. We might have turned to duct tape or zip ties, but bungee cord works, too, as you can see in the finished product.

Honestly, though, the bungee is good because you can stretch it to remove the battery for charging. We might have just cannibalized the drill for its motor, but next time you have a tool with no battery, it might be worth looking to see if you could modify the tool.

Bungees are great for robots, too. Or, you can lay siege on your neighbors.

Arduino Cable Tracer Helps Diagnose Broken USB Cables

July 18, 2021 by Lewin Day 31 Comments

We’ve all found ourselves swimming amongst too many similar-looking USB cables over the years. Some have all the conductors and functionality, some are weird power-only oddballs, and some charge our phones quickly while others don’t. It’s a huge headache and one that [TechKiwiGadgets] hopes to solve with the Arduino Cable Tracer.

The tracer works with USB-A, Mini-USB, Micro-USB, and USB-C cables to determine whether connections are broken or not and also to identify wiring configurations. It’s built around the Arduino Mega 2560, which is ideal for providing a huge amount of GPIO pins that are perfect for such a purpose. Probing results are displayed upon the 2.8″ TFT LCD display that makes it easy to figure out which cables do what.

It’s a tidy build, and one that we could imagine would be very useful for getting a quick go/no-go status on any cables dug out of a junk box somewhere. Just remember to WIDLARIZE any bad cables you find so they never trouble you again. Video after the break.

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Fixing Noisy Measurements On An Owon XDM2041 Bench Multimeter

July 14, 2021 by Maya Posch 21 Comments

After purchasing an Owon XDM2041 bench multimeter for an automated test setup, [Petteri Aimonen] was disappointed to find that at especially the higher mega Ohm ranges, the measured values were jumping around a lot and generally very inaccurate. Since this is an approximately $170 bench multimeter and Owon support wasn’t cooperating, [Petteri] set out to fix the issue, starting with a solid teardown.

As noted by [Petteri], there’s not a whole lot inside one of these multimeters. The main board with the guts of the whole system contains a GigaDevices GD32F103CBT6 MCU coupled with the star of the show: the HYCON Technology Corporation’s HY3131 multimeter chip. After a peek at the HY3131 datasheet, the culprit was quite apparent: while sampling the presence of mains voltage noise is usually suppressed through the selection of an appropriate crystal.

Unfortunately, instead of the recommended 4.9152 MHz crystal per the reference schematic for the HY3131, Owon’s engineers had apparently opted for a 4 MHz crystal instead, and so it’s essentially aliasing the line noise.

[Petteri] figured that the resulting sampling timing might work well enough with 60 Hz line frequency, but clearly with 50 Hz there was a lot of noise sneaking into the measurements. After swapping the crystal with a 3.072 MHz one, there was a marked improvement, as the plot shows.

3D Printed CNC Knee Mill

July 13, 2021 by Danie Conradie 52 Comments

CNC mills will never match real heavy metal mills on hard materials, but that won’t stop people from pushing the limits of these DIY machines. One of the usual suspects, [Ivan Miranda] is at it again, this time building a knee mill from aluminum extrusions and 3D printed fittings. (Video after the break.)

Most DIY CNC milling machines we see use a gantry arrangement, where the bed is fixed while everything else moves around it. On most commercial metal milling machines, the table is the moving part, and are known as knee mills. In the case of [Ivan]’s mill, the table can move 187 mm on the X-axis and 163 mm on the Y-axis. The 1.5 kW spindle can move 87 mm in the Z-axis. All axes slide on linear rails and are driven by large stepper motors using ball screws. The table can also be adjusted in the Z-direction to accept larger workpieces, and the spindle can be tilted to mill at an angle.

To machine metal as [Ivan] intended, rigidity is the name of the game, and 3D printed parts and aluminum extrusion will never be as rigid as heavy blocks of steel. He says claims that the wobble seen on the video is due to the uneven table on which the mill was standing. Of course, a wobbly base won’t be doing him any favors. [Ivan] also had some trouble with earthing on the spindle. He nearly set his workshop on fire when he didn’t notice tiny sparks between the cutter and aluminum workpiece while he was cooling it with isopropyl alcohol. This was solved with the addition of the grounding wire.

While the machine does have limitations, it does look like it can machine functional metal parts. It could even machine metal upgrades for its 3D printed components. One possible way to improve rigidity would be to cast the frame in concrete. [Ivan] has built several other workshop tools, including a massive 3D printer and a camera crane. Continue reading “3D Printed CNC Knee Mill” →

3D-Printed, Hot-Swap Keyboard PCB Generator Is Super Cool

July 12, 2021 by Kristina Panos 4 Comments

About a month ago, [50an6xy06r6n] shared their hot swap 3D-printed circuit board for keyboard design with the mechanical keyboard subreddit. It’s more of a prototyping tool than a permanent fixture, though nothing is stopping you from using it permanently. Well, now it’s even better, and open source to boot.

[50an6xy06r6n] came up with this to test split ergo layouts faster and not have to solder anything — the switch pins make contact with the row wires and folded diode legs. In fact, prepping all the diodes is probably the thing that takes the longest.

The design can be generated from layout data, or you can convert directly from a KLE JSON file. We love how delightfully clean this keyboard breadboard generator looks, and we wish we had thought of it!

[50an6xy06r6n]’s PCB generator currently supports Cherry MX/clones and Kailh Choc switch footprints. If you want ALPS, somebody’s gonna have to send [50an6xy06r6n] some ALPS to make that happen.

As long as all the contact points are good, you should be able to use this as the final PCB indefinitely. We’ve certainly seen our share of 3D-printed wire guides. Really, you could print the whole thing, including the switches.

Making Teeny Clamps With Hand Tools

July 11, 2021 by Lewin Day 19 Comments

Sometimes you need a small clamp, and sometimes it’s nice to use tools you’ve made yourself. [Neil] from [Pask Makes] delivers on both counts, with incredibly cute little clamps that he whipped up in his own home shop. You can even make them with hand tools!

The first step is to cut out a section of flat steel bar, and then drill a hole in the middle. The flats that form the key clamping surfaces can then be cut using a hacksaw. From there, it’s a matter of cleaning up the resulting blank with a file to take off sharp edges and neaten up the flats.

Drilling and tapping the main hole through the bottom of the clamp is the next job, and getting the hole straight and true is key to making a good usable clamp. The video shares tips on how to do this with even a simple cordless drill, by using a vice and a wood guide to keep things on track. The swiveling nut is then made out of a piece of round bar, and installed on the end of a bolt to create a nice clamping surface. A cute little brass handle is used to tighten it up.

It’s a useful tool, and the video goes on to show how the clamp can be made more quickly using higher-end facilities. While small clamps can be had cheaply, the video notes that making tools is fun and we think that’s as good a reason as any to make your own.

We’ve seen [Neil]’s work before, particularly in the case of this stunning “bladeless fan” build. Video after the break.

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