A Simple Yet Feature-Packed Programmable DC Load

If you’ve got the hankering to own a lab full of high-end gear but your budget is groaning in protest, rolling your own test equipment can be a great option. Not everything the complete shop needs is appropriate for a DIY version, of course, but a programmable DC load like this one is certainly within reach of most hackers.

This build comes to us courtesy of [Scott M. Baker], who does his usual top-notch job of documenting everything. There’s a longish video below that covers everything from design to testing, while the link above is a more succinct version of events. Either way, you’ll get treated to a good description of the design basics, which is essentially an op-amp controlling the gate of a MOSFET in proportion to the voltage across a current sense resistor. The final circuit adds bells and whistles, primarily in the form of triple MOSFETS and a small DAC to control the set-point. The DAC is driven by a Raspberry Pi, which also supports either an LCD or VFD display, an ADC for reading the voltage across the sense resistor, and a web interface for controlling the load remotely. [Scott]’s testing revealed a few problems, like a small discrepancy in the actual amperage reading caused by the offset voltage of the op-amp. The MOSFETs also got a bit toasty under a full load of 100 W; a larger heatsink allows him to push the load to 200 W without releasing the smoke.

We always enjoy [Dr. Baker]’s projects, particularly for the insight they provide on design decisions. Whether you want to upgrade the controller for a 40-year-old game console or giving a voice to an RC2014, you should check out his stuff.

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A Rope Maker You Can 3D Print At Home

Ropes are one of those things that, while possible to make by hand, having a little mechanical help goes a long way in their manufacture. [b33ma247] wanted just such a rig, so set about building one from scratch.

It’s a simple device, but one that makes the task much easier. A series of gears are printed, which assemble on to a frame to form the winding mechanism that weaves the rope. There’s also a slide, a rope separator, and a weight carriage to ensure proper tension is kept on the string during the weaving process. The mechanism is driven by a power drill, though this could be easily replaced with a hand crank if full manual operation was desired.

It’s a project which shows if you have a 3D printer, you can make a lot of other useful tools for your workshop too. We see similar approaches taken when it comes time to wind coils, too. Video after the break.

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3D Printed Breadboard Helper Makes Wiring Neater And Easier

Breadboards make it simple to prototype and test circuits. If you use flexible wires with pins to make connections, it usually results in a rat’s nest. For many of us, using solid wire makes a rat’s nest, too. However, the very neat among us will cut solid wire to just the right length and strip just the right amount of wire and lay the wires very flat and neat along the board. [Moononournation] did a 3D print that makes the latter method much easier. You can find his Breadboard Wire Helper on Thingiverse and see a video, below.

The idea is simple: start with a piece of wire stripped on one side, then count out the number of holes it needs to traverse and push the stripped end through the hole. Trim the wire to fit. To complete the other side, lay the wire flat along the tool to the edge. Now you can see where to strip that side of the wire. After you remove the insulation, you can bend the wire down and cut the wire to fit. Now you have a perfect size and shape wire to place in the actual breadboard.

Granted, this isn’t that hard to do with the existing breadboard if it isn’t too packed. You could even use a spare breadboard. But it is a little easier to trim the wire to the right size with this jig. If you don’t want to 3D print it, you could probably pull the tape off the back of a cheap board and remove the springs to get a similar effect.

So while this little tool probably won’t change your life, it might make it a little easier. What other tools do you use when breadboarding? Let everyone know in the comments.

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Steel Pegboard Makes For A Tidy Charging Station

Do you have a bunch of electronic devices that all have different styles of chargers and batteries? Of course you do, so does everyone else. While there’s been some headway made towards standardizing on USB (and more recently, USB-C) for charging, there are still plenty of gadgets out there that march to the beat of their own DC adapter. For all those devices, [Tom Barnes] has a tip for making a cheap and easy centralized charging station.

The idea is to get a power strip, ideally one that has a switch on it, and use zip ties to attach it to a piece of pegboard. [Tom] used a nice black steel board which is obviously very strong and shouldn’t be bothered by any potentially high temperatures, but you could get away with the hardware store MDF variety if you had to.

All your chargers, mounted around the periphery of the board with Velcro hook and loop fasteners, have their individual power cords run through to the back of the board where they are nearly routed and zip tied. This is where using the steel pegboard really helped, as it has a lip around the edge that makes a void for all the wires to be run through when hung on the wall. If your particular flavor of pegboard doesn’t have that space behind it, you’d either have to settle for running the wires across the front or build out your own space in the back using a wooden frame.

Even in our high-tech world, no shop is truly complete without pegboard. Whether you’re using it to vertically mount your development boards, or pushing it around on wheels to keep your tools close at hand, there’s no shortage of ways to use this versatile material.

Adding A Digital Readout To A Wood Lathe

The benefit of living in the modern era is that there are plenty of affordable machine tools on the market for the budding maker. However, to meet lower price points, products often forgo some of the nice-to-have features that make working easier. Of course, if you’ve got the skills to do it yourself, this needn’t be a problem, as [Zach] demonstrates.

[Zach] enjoyed using his wood lathe, but it didn’t come with a digital readout. Thankfully, retrofitting one was an easy, straightforward project. After a little research, a Hall effect sensor was chosen to detect the rotational speed of the lathe. The spindle was thus fitted with several magnets to trigger the sensor, allowing for higher resolution than just using a single device. An Arduino Nano was then used to monitor the output of the Hall effect sensor, displaying the rotational speed on a set of 7-segment displays. The project was then given its own custom PCB, and a nice 3D printed enclosure to fit it to the body of the lathe.

It’s a project that shows how easy it is to add functionality to basic machine tools using maker components. It also serves to demonstrate the value in giving a project a proper enclosure, to enable it to survive in a workshop environment. We’ve seen other hacky DRO mods before, too. Video after the break.

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Cable Operated Blast Door Needs No Power

Every well-equipped wood shop has a dust collection system, with blast gates at every tool to direct the suction power where you need it. If these gates are hard to reach they can be real pain to operate. [Cosmas Bauer] had this problem with his table saw, and created a convenient cable-operated mechanism.

The dust chute on table saw is on the back end, meaning he needs to walk around it to open it, and then walk back to the front to operate the machine. As we all know, laziness increased efficiency can be an excellent reason for projects. Electronics or pneumatics might get the job done, but [Cosmas] realised that a mechanical system might be simpler and more reliable.  Being a woodworker, he built most of the system out of wood.

The blast door itself is held in the closed position by a piece of elastic tubing. To pull it open, he attached a bicycle cable to the blast door, with the other side attached to a latching mechanism that is the star of the show. It’s a rotating disc, with the end of the cable and operating handle attached on the outer edge. A slot track is cut in the disc, in which a pin on the end of a short arm slides. It has a few sharp corners in the track, which forces the pin to only go around in one direction, and to latch in two possible positions when released. Check out the video after the break to see it in action.

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Electrification Of A Cheap Bead Roller

We all have old projects which maybe didn’t quite deliver knocking about, sometimes they gather dust for years. They have a use though, in that when you *really* need that part you can lift it from that forgotten project. That’s what [Mustie1] did with a forgotten electric bicycle project, he took its motor and used it to automate his bead roller.

A bead roller is a tool used in the world of automotive bodywork to press a bead — a continuous depression — into a piece of sheet metal. The inexpensive roller he had fitted in a bench vice, and was operated by means of a handle. Unfortunately the size of the tool meant that it was difficult to operate at the same time as rolling a precise bead, so improvement was required.

He first considered using a cordless drill, but then remembered the electric bicycle project. Its geared motor had come from an electric wheelchair and certainly possessed the right speed, but he needed a suitable sprocket. This was supplied from a scrap engine-assisted bicycle that he’d acquired, and proved to be perfect for the job. The final automated roller used the trigger controller from a cordless drill mounted in a foot switch, and the roller mounted on a stand repurposed from a piece of gym equipment. The result is a useful, and above all controllable, tool that can run a perfect bead in any shape desired on a piece of sheet metal.

Surprisingly this is the first bead roller we’ve featured here, but sheet metal work is a constant in hardware hacker projects. Read our guide to sheet metal bending, for a start.

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