Flexible PCB Becomes The Actuator

An electromagnetic coil gun takes a line of electromagnets working together to form a moving electromagnetic field. These fields accelerate a project and boom, you have electricity moving matter, often at an impressive rate of speed.

[Carl Bugeja] has taken the idea and in a sense turned it upon its head with his flexible PCB actuator. Now the line of electromagnets are the moving part and the magnetic object the stationary one. There is still a line of flat PCB inductors in the classic coil gun configuration, but as the title suggests on a flexible substrate.

The result is a curiously organic motion reminiscent of some lizards, caterpillars, or snakes. It can move over the magnet in a loop, or flex in the air above it. It’s a novel moving part, and he’s treated us to a video which we’ve placed below the break.

He has plans to put it to use in some form of robot, though while it certainly has promise we’d be interested to know both what force it can produce and whether flexible PCB is robust enough for repeated operation. We salute him for taking a simple idea and so effectively proving the concept.

We’ve brought you [Carl]’s work before, most notably with his PCB motor.

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An Integrated Electromagnetic Lifting Module for Robots

The usual way a robot moves an object is by grabbing it with a gripper or using suction, but [Mile] believes that electromagnets offer a lot of advantages that are worth exploring, and has designed the ELM (Electromagnetic Lifting Module) in order to make experimenting with electromagnetic effectors more accessible. The ELM is much more than just a breakout board for an electromagnet; [Mile] has put a lot of work into making a module that is easy to interface with and use. ELM integrates a proximity sensor, power management, and LED lighting as well as 3D models for vertical or horizontal mounting. Early tests show that 220 mW are required to lift a 1 kg load, but it may be possible to manage power more efficiently by dynamically adjusting drive voltage depending on the actual load.

[Mile]’s focus on creating an easy to use, integrated solution that can be implemented easily by others is wonderful to see, and makes the ELM a great entry for The Hackaday Prize.

The Magic that Goes into Magnets

Every person who reads these pages is likely to have encountered a neodymium magnet. Most of us interact with them on a daily basis, so it is easy to assume that the process for their manufacture must be simple since they are everywhere. That is not the case, and there is value in knowing how the magnets are manufactured so that the next time you pick one up or put a reminder on the fridge you can appreciate the labor that goes into one.

[Michael Brand] writes the Super Magnet Man blog and he walks us through the high-level steps of neodymium magnet production. It would be a flat-out lie to say it was easy, but you’ll learn what goes into them and why you don’t want to lick a broken hard-drive magnet and why it will turn to powder in your mouth. Neodymium magnets are probably unlikely to be produced at this level in a garage lab, but we would love to be proved wrong.

We see these magnets everywhere, from homemade encoder disks, cartesian coordinate tables, to a super low-power motor.

Dollar Store PCB Holder System

As you get into electronic fabrication and repair, one of the first things you realize is how hard it can be to hold a PCB still while you work on it. Securing them is difficult due to their very nature: they’re often weird shapes, quite fragile, and of course need to be electrically isolated. If you don’t mind spending the money, and have the time to wait on it getting delivered, you can order some nice purpose-built systems for holding PCBs online. But what if you need something fast and cheap?

[Paul Bryson] might have the solution for you. On his blog he’s documented how a trip to the dollar store and some parts from the junk bin allowed him to create a practical system for holding multiple PCBs of various shapes and sizes. The most exotic element of the build here are the hexagonal standoffs; and if you haven’t already salvaged a bunch of those from a curbside computer, he even gives the Mouser link where you can buy them new for a few cents each.

Each individual stanchion of the system is made up of a 3/4″ round magnet with a hex standoff glued to the top. Over the standoff, [Paul] slipped a rubber grommet which gives a nice non-conductive slot to put the edge of the PCB in. Otherwise, a second hex standoff screwed into the first can be used to clamp down on the board. Adjusting the height is as simple as adding a couple more magnets to the stack.

Of course, magnets need something metal to stick on. For that, [Paul] purchased some steel pie pans and matching rack from the dollar store. The round pans are easy to handle and give him plenty of surface area, and the rack makes for an exceptionally convenient storage unit for all the components. The conductivity of the pans might be a concern, but nothing the application of a rubberized spray coating couldn’t fix.

We’ve covered similar systems before, but this one certainly looks to take the top spot in terms of economics. The only thing that would be cheaper would be a few feet of PLA filament and a rubber band.

Coming Back to Curving Bullets

What do you do when you have time, thousands of dollars worth of magnets, and you love Mythbusters? Science. At least, science with a flair for the dramatics. The myth that a magnetic wristwatch with today’s technology can stop, or even redirect, a bullet is firmly busted. The crew at [K&J Magnetics] wanted to take their own stab at the myth and they took liberties.

Despite the results of the show, a single magnet was able to measurably alter the path of a projectile. This won’t evolve into any life-saving technology because the gun is replaced with an underpowered BB gun shooting a steel BB. The original myth assumes a firearm shooting lead at full speed. This shouldn’t come as any surprise but it does tell us how far the parameters have to be perverted to magnetically steer a bullet. The blog goes over all the necessary compromises they had to endure in order to curve a bullet magnetically and their results video can be seen below the break.

Here we talk about shooting airplane guns so they don’t get mislead after leaving the barrel, and some more fun weaponry from minds under Churchill’s discretion.

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Magnetic Spheres Line Up for Rotary Encoder Duty

When it comes to rotary encoders, there are plenty of options. Most of them involve putting a credit card number into an online vendor’s website, though, and that’s sometimes just not in the cards. In that case building your own, like this encoder using magnetic spheres, is a pretty cool way to go too.

If he’d had less time to spare, we imagine [Antonio Ospite] would have gone for a commercial solution rather than building an encoder from scratch. Then again, he says his application had noise considerations, so maybe this was the best solution overall. He had some latching Hall effect sensors lying around, but lacked the ring magnet that is usually used with such sensors in magnetic encoders. But luckily, he had a mess of magnetic spheres, each 5 mm in diameter. Lined up in a circle around a knob made from a CD spindle, the spheres oriented themselves with alternating poles, which is just what the Hall sensors want to see. The sensors were arranged so the pulses are 90° apart, and can resolve 4.29° steps. Check out the video below to watch it work.

Small, cheap and effective are always good things. But magnets aren’t the only thing behind homebrew rotary encoders. A couple of microswitches might do in a pinch, or maybe even scrapped hard drives would suffice.

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DIY Magnetic Actuator, Illustrated And Demonstrated

Electromagnetic actuators exert small amounts of force, but are simple and definitely have their niche. [SeanHodgins] took a design that’s common in flip-dot displays as well as the lightweight RC aircraft world and decided to make his own version. He does a good job of explaining and demonstrating the basic principles behind how one of these actuators works, although the “robotic” application claimed is less clear.

It’s a small, 3D printed lever with an embedded magnet that flips one way or another depending on the direction of current flowing through a nearby coil. Actuators of this design are capable of fast response and have no moving parts beyond the lever itself, meaning that they can be made very small. He has details on an imgur gallery as well as a video, embedded below.

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