Parts

613 Articles

Unusual Port Combines DisplayPort And HDMI

March 12, 2024 by 22 Comments

Everyone knows you can’t plug an HDMI cable into a DisplayPort… port, and yet a recent video from [Jon Bringus] challenges that seemingly obvious assumption. The hardware in question is a variant of the 2013-era Xi3 X7A mini PC, code-named ‘Piston’ and also known as a ‘Steambox’, from back when that was still something that Valve was working on. Although the physical format here is definitely quaint, it might be implementing DisplayPort Dual-Mode (DP++), which was introduced around the same time.

With DP++ the DP port can detect when a DVI or HDMI adapter is connected and then transmit DVI/HDMI TMDS signals rather than DP signals. Since DP and HDMI/DVI use a different signaling scheme, normally an active adapter would be required. One disadvantage of DP++ is that the HDMI signal will be limited to e.g. 1920×1080 @ 120 Hz and 4K only at 30 Hz.

Normally a DP++ port is marked as such, and requires an adapter that works with the DP++ port. What Xi3 did in this case to make regular DP and HDMI connectors work seems to be somewhat of a mystery, with any information on this type of port being rather scarce. [Jon] thinks he may have found the part itself listed on Mouser, but isn’t completely sure.

Feel free to leave your thoughts and any information you have on this oddity in the comments.

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That’s A Lot Of Building Systems

March 8, 2024 by 9 Comments

The only thing makers like more than building things is making systems to build things. [Eric Hunting] has compiled a list of these modular building systems.

You’ve certainly heard of LEGO, grid beam, and 80/20, but what about Troxes or Clickaloo? The 70 page document has a helpful index at the beginning arranged in families of similar systems followed by information about each and some helpful links.

As the well-known XKCD comic likes to point out, the issue with standards is that they tend to proliferate instead of getting adopted, so this might be a good list to check before you start to implement your brilliant spin on modular construction. It’s possible the right system is already waiting for you.

The list certainly isn’t exhaustive, but it’s a good place to start. If you do have the modular building system that will solve all the world’s problems though, by all means, send it to the tipsline!

What’s A Transfluxor?

March 3, 2024 by 11 Comments

In the 1967 movie The Graduate, a wise older man gives some advice to the title character: plastics. Indeed, plastics would become big business. In 1962, though, a computer-savvy character might have offered a different word: transfluxor. What’s a transfluxor? Well, according to computer history sleuth [Ken Shirriff], it was the heart of a 20-pound transistor computer from Arma. Of course, plastics turned out to be a better bet, but in 1962, the transfluxor seemed to be the wave of the future.

In 1962, most computers were room-sized, but the Arma was “micro” taking up just 0.4 cubic feet — less than an Apple II. It would eventually spawn computers used in ships at sea and airplanes ranging from the Concorde to Air Force One.

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Washing Machine Motors Unlocked

February 29, 2024 by 19 Comments

There’s great potential in salvaging a motor from a broken appliance, but so often the part in question is very specific to its application, presenting a puzzle of wires to the experimenter. This was very much the case with older washing machines and other white goods, and while their modern equivalents may have switched to more understandable motors, there are still plenty of the older ones to be had. [Matthias random stuff] sheds a bit of light on how these motors worked, by means of a 1980s Maytag washing machine motor.

Many of us will be used to old-style induction motors, in which two windings were fed out of phase via a large capacitor. This one doesn’t have a capacitor, instead it has a primary winding and a secondary one with a higher resistance. We’re not quite sure the explanation of the resistance contributing to a phase shift holds water, however this winding is connected in for a short time at start-up by a centrifugal switch. Even better, reversing its polarity reverses the direction of the motor.

The result is a mess of wires demystified, and a mains powered motor with a bit of strength for your projects. We’ve let a few of these motors slip through our fingers in the past, perhaps we shouldn’t have been so hasty.

This is a subject that we’ve looked at in the past.

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The Photodiode You Never Knew You Had

February 28, 2024 by 33 Comments

Optoelectronics hold a range of possibilities for the hardware experimenter — indeed who among us hasn’t added LEDs aplenty to our work? What many of us may be unaware of though is that an LED is also a photodiode, and can even be persuaded to generate usable quantities of power. [Voltative] takes a look at this phenomenon with a series of experiments.

Lighting up an LED from a set of other LEDs is pretty cool, as is powering a calculator, or even the calculator powering itself from its on-board LED. But what caught our eye was using two LEDs as a data link, with both of them acting as transmitter and receiver (something on searching we find we’ve seen before). The possibilities there become interesting indeed.

Given that we are now surrounded by LEDs, from OLED screens to LED lighting, we can’t help wondering what the photodiode performance of some other types of part might be. Would the large area of a lighting LED give a better result for example, or would the phosphorescent coating of a white LED make it useless. We feel there’s more scope for experimentation here.

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Op-Amp Drag Race Turns Out Poorly For 741

February 23, 2024 by 32 Comments

When it was first introduced in 1968, Fairchild’s 741 op-amp made quite a splash. And with good reason; it packed a bunch of components into a compact package, and the applications for it were nearly limitless. The chip became hugely popular, to the point where “741” is almost synonymous with “op-amp” in the minds of many.

But should it be? Perhaps not, as [More Than Electronics] reveals with this head-to-head speed test that compares the 741 with its FET-input cousin, the TL081. The test setup is pretty simple, just a quick breadboard oscillator with component values selected to create a square wave at approximately 1-kHz, with oscilloscope probes on the output and across the 47-nF timing capacitor. The 741 was first up, and it was quickly apparent that the op-amp’s slew rate, or the rate of change of the output, wasn’t too great. Additionally, the peaks on the trace across the capacitor were noticeably blunted, indicating slow switching on the 741’s output stage. The TL081 fared quite a bit better in the same circuit, with slew rates of about 13 V/μS, or about 17 times better than the 741, and nice sharp transitions on the discharge trace.

As [How To Electronics] points out, comparing the 741 to the TL081 is almost apples to oranges. The 741 is a bipolar device, and comparing it to a device with JFET inputs is a little unfair. Still, it’s a good reminder that not all op-amps are created equal, and that just becuase two jelly bean parts are pin compatible doesn’t make them interchangeable. And extra caution is in order in a world where fake op-amps are thing, too.

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A Classroom-Ready Potentiometer From Pencil And 3D Prints

February 19, 2024 by 18 Comments

If you need a potentiometer for a project, chances are pretty good that you’re not going to pick up a pencil and draw one. Then again, if you’re teaching someone how a variable resistor works, that old #2 might be just the thing.

When [HackMakeMod] realized that the graphite in pencil lead is essentially the same thing as the carbon composition material inside most common pots, the idea for a DIY teaching potentiometer was born. The trick was to build something to securely hold the strip while making contact with the ends, as well as providing a way to wipe a third contact across its length. The magic of 3D printing provided the parts for the pot, with a body that holds a thin strip of pencil-smeared paper securely around its inner diameter. A shaft carries the wiper, which is just a small length of stripped hookup wire making contact with the paper strip. A clip holds everything firmly in place. The video below shows the build process and the results of testing, which were actually pretty good.

Of course, the construction used here isn’t meant for anything but demonstration purposes, but in that role, it performs really well. It’s good that [HackMakeMod] left the body open to inspection, so students can see how the position of the wiper correlates to resistance. It also makes it easy to slip new resistance materials in and out, perhaps using different lead grades to get different values.

Hats off to a clever build that should be sure to help STEM teachers engage their students. Next up on the lesson plan: a homebrew variable capacitor.

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