Simple Magnetic Levitator

February 10, 2024 by Al Williams 9 Comments

[Stoppi] always has exciting projects and, as you can see in the video below, the latest one is a very simple magnetic levitator design. The design is classic and simple: a 5 V regulator IC, a Hall effect sensor, a 741 op amp, and a MOSFET to turn the electromagnet on and off.

Sure, there are a few passive components and a diode, too, but nothing exotic. The sensor normally presents 2.5 V of output. The voltage rises or drops depending on the polarity of the magnetic field. The stronger the field, the more the voltage changes away from the 2.5 V center.

The op amp acts as a comparator with a potentiometer setting the trip point. As the ball moves up towards the coil, the voltage increases, triggering the comparator, which turns off the FET. With no current through the coil, there’s no more electromagnet, and the ball starts to fall.

Of course, as the ball falls, the voltage from the sensor also drops, and this eventually turns on the electromagnet. The ball eventually reaches a relatively stable position.

This is one of those cases where a simple analog circuit might work better than a digital one. Or make it hard on yourself and use an FPGA.

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Power Supply Efficiency Measurements

February 9, 2024 by Al Williams 12 Comments

Even if you don’t have a Rohde Schwarz oscilloscope, you can still enjoy their recent video about using an oscilloscope to measure power supply efficiency. Of course, you don’t have to have a scope to do this. You can use a voltmeter and an ammeter, but it is very straightforward if you have a four-channel scope with a pair of current probes.

Of course, if you can measure the voltage and the current at the input, you can calculate the input power. Then again, most scopes these days can do the math for you. Then, you make the same measurement and calculation at the output. If you know the input and output power, you can calculate a percentage or many scopes can do it for you now.

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3D Printing Silicone Parts

February 8, 2024 by Al Williams 6 Comments

Silicone is a useful material for many purposes. Traditionally, creating something out of silicone required injection molding. That’s not difficult, but it does require a good bit of setup. As [Formlabs] points out in a recent video, there are at least three other routes to create silicone parts that utilize 3D printing technology that might fit your application better, especially if you only need a few of a particular item. You can see the video below.

The three methods are either printing silicone directly, printing a mold, casting silicone, or using high-performance elastomers, which are very silicone-like. Of course, as you might expect, some of this is aimed at prompting some of [Formlab’s] products, like a new silicone resin, and you can’t blame them for that.

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The End Of Landlines?

February 8, 2024 by Al Williams 95 Comments

Imagine if, somehow, telephones of all kinds had not been invented. Then, this morning, someone entered a big corporation board room and said, “We’d like to string copper wire to every home and business in the country. We’ll get easements and put the wires on poles mostly. But some of them will go underground where we will dig tunnels. Oh, and we will do it in other countries, too, and connect them with giant undersea cables!” We imagine that executive would be looking for a job by lunchtime. Yet, we built that exact system and with far less tech than we have today. But cell phones have replaced the need for copper wire to go everywhere, and now AT&T is petitioning California to let them off the hook — no pun intended — for servicing landlines.

The use of cell phones has dramatically decreased the demand for the POTS or plain old telephone service. Even if you have wired service now, it is more likely fiber optic or, at least, an IP-based network connection that can handle VOIP.

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The Revolver: A 3D-Printed… Screwdriver!

February 8, 2024 by Al Williams 19 Comments

You know those “What my friends think I do” vs “What I actually do” memes? Well there should be one for 3D printing that highlights what you think you’ll do before buying your first printer vs what you actually wind up printing once you get it!

However, thanks to [Revolver3DPrints] you can fulfill your dream of printing a useful tool that looks like a commercial product, the Revolver two-speed screwdriver. The screwdriver isn’t motorized, but it has an interesting midsection that can be rotated to spin the bit, and you can select between a speed and torque mode.

The Revolver isn’t a solution looking for a problem. The designer noted a few issues with normal screwdrivers. They are hard to get into tight spaces, which was the biggest issue. The Revolver is compact, and since you turn its midsection, you don’t have to have clearance for your hand on the top. The gear ratios allow you to apply more torque without needing a long handle.

As you may have guessed, the internal arrangement is a planetary gear drive. You might consider if you want to print this using resin or FDM printing. You also need some screwdriver bits, some glue, and a few magnets to complete the project. If you prefer to make a motorized screwdriver, we’ve seen that done, too.

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Metal Crystal Stops Electrons

February 7, 2024 by Al Williams 14 Comments

Researchers at Rice University have found an alloy of copper, vanadium, and sulfur that forms crystals that, due to quantum effects, can trap electrons. This can produce flat bands, which have been observed in 2D crystals previously. The team’s results are the first case of a 3D crystal with that property.

The flat band term refers to the electron energy bands. Normally, the electrons change energy levels based on momentum. But in a flat band, this doesn’t occur. This implies that the electrons are nearly stationary, which leads to unique optical, electronic, and magnetic properties. In addition, flat-band materials often exhibit unusual behavior, such as exotic quantum states, ferromagnetism, or even superconductivity.

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Your 1983 Video Phone Is Finally Ready

February 7, 2024 by Al Williams 8 Comments

If you read Byte magazine in 1983, you might have expected that, by now, you’d be able to buy the red phone with the video screen built-in. You know, like the one that appears on the cover of the magazine. Of course, you can’t. But that didn’t stop former Hackaday luminary [Cameron] from duplicating the mythical device, if not precisely, then in spirit. Check it out in the video, below.

While the original Byte article was about VideoTex, [Cameron] built a device with even more capability you couldn’t have dreamed of in 1983. What’s more, the build was simple. He started with an old analog phone and a tiny Android phone. A 3D-printed faceplate lets the fake phone serve as a sort of dock for the cellular device.

That’s not all, though. Using the guts of a Bluetooth headset enables the fake phone’s handset. Now you can access the web — sort of a super Videotex system. You can even make video calls.

There isn’t a lot of detail about the build, but you probably don’t need it. This is more of an art project, and your analog phone, cell phone, and Bluetooth gizmo will probably be different anyway.

Everyone always wanted a video phone, and while we sort of have them now, it doesn’t quite seem the same as we imagined them. We wish [Cameron] would put an app on the phone to simulate a rotary dial and maybe even act as an answering machine.

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