VFETs are (Almost) Solid State Tubes
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VFETs are (Almost) Solid State Tubes
We always enjoy videos from [w2aew]. His recent entry looks at vertical or VFETs, which are, as he puts it, a JFET that thinks it is a triode. He clearly explains how the transistor works as a conductor unless you bias the gate to form a depletion zone.
The transistors have a short channel, which means they conduct quite well. The low gate resistance and capacitance mean the devices can also switch very quickly. These devices were once in vogue for audio applications. However, they’d fallen out of favor until recently. The reason is that they work quite well in switching power supplies.
How good is the on resistance? So good that his meter reported the probes were shorted instead of measuring the resistance. Pretty good. We’ve seen these VFET transistors used as switches to drive magnetic field coils many years ago and they replaced much more complex circuitry.
The curve tracer in the video is a beautiful instrument of its own. The digital displays give it a high tech yet retro look. A curve tracer, if you haven’t used one, plots stepped voltages against current flowing, and is very useful for examining semiconductor devices. While not as fancy, it is possible to make one to connect to a scope quite easily.
We are pretty sure that it is a Tektronix 576. We watched a repair of a similar unit, the 577, if you’d like to see some (probably) similar insides.
youtube.com/embed/93ke5wM0gZ0?…
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Record-Breaking Robots at Guinness World Records
If you ever wanted to win a bar bet about a world record, you probably know about the Guinness book for World Records. Did you know, though, that there are some robots in that book? Guinness pointed some out in a recent post.
Ever wonder about the longest table-tennis rally with a robot or the fastest robotic cube solver? No need to wonder anymore.
Our favorite was the fastest robot to solve a puzzle cube. This robot solved the Rubik’s Cube in 103 milliseconds! Don’t blink or you’ll miss it in the video embedded. Of course, the real kudos go to the team that created the robot: [Matthew Patrohay], [Junpei Ota], [Aden Hurd], and [Alex Berta].
Another favorite was the smallest humanoid robot. In order to win this record, the robot must be able to move its shoulders, elbows, knees, and hips just like a human. It also has to be able to walk on two feet. This tiny little guy meets the requirements and stands only 57.6 mm (2.26 in) tall! Created by [Tatsuhiko Mitsuya] in April 2024, this robot can be controlled via Bluetooth.
We’ve seen entries in this category before — check them out in Almost Breaking The World Record For The Tiniest Humanoid Robot, But Not Quite.
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mstdn.jpが日本公式サーバと誤認されやすいのを、あえてjapanをぶつけることで上書きしようとしたmastodon-japan.netですが、
先に閉鎖をアナウンスすることになり、今度はmstdn.jpがサービス終了すると誤解させることになり……
■ これを覚えておいてね
・mstdn.jpは運営継続中（閉鎖予定なし）
2017年4月に日本のMastodonブームを牽引した老舗サーバですが、名前だけそれっぽいだけで、私設のサーバです。運営譲渡が2回あり、現在はSujitechが運営。閉鎖ニュースの誤情報が多いので注意してね。
・mastodon-japan.netが2026年1月31日に閉鎖予定
2022年11月に設置された比較的新しいサーバで、くろりんごさんが設置。こちらもあえてjapanを名乗っていますが、私設のサーバです。イーロンマスクがTwitterを引き継いだ際にMastodonに登録する人が激増した際、既存サーバだけで受け入れるのは大変だからと、新しいサーバを立てて支えてくれました。
今回閉鎖となりましたが、Mastodon Server Covenantによる、閉鎖3ヶ月前に事前アナウンスする約束を守ってくれています。
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@petersuber aww, that's really too bad.
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@eccosilvia l'importanza della prevenzione e della sicurezza, altro che fattore "C" .
Una ragione per vedere positivamente la sparizione totale della fiamma viva dalle case.... comunque Silva ha un "C" di generosissime dimensioni 🤭 ...
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VFETs are (Almost) Solid State Tubes
We always enjoy videos from [w2aew]. His recent entry looks at vertical or VFETs, which are, as he puts it, a JFET that thinks it is a triode. He clearly explains how the transistor works as a conductor unless you bias the gate to form a depletion zone.
The transistors have a short channel, which means they conduct quite well. The low gate resistance and capacitance mean the devices can also switch very quickly. These devices were once in vogue for audio applications. However, they’d fallen out of favor until recently. The reason is that they work quite well in switching power supplies.
How good is the on resistance? So good that his meter reported the probes were shorted instead of measuring the resistance. Pretty good. We’ve seen these VFET transistors used as switches to drive magnetic field coils many years ago and they replaced much more complex circuitry.
The curve tracer in the video is a beautiful instrument of its own. The digital displays give it a high tech yet retro look. A curve tracer, if you haven’t used one, plots stepped voltages against current flowing, and is very useful for examining semiconductor devices. While not as fancy, it is possible to make one to connect to a scope quite easily.
We are pretty sure that it is a Tektronix 576. We watched a repair of a similar unit, the 577, if you’d like to see some (probably) similar insides.
