transistor

118 Articles

Bell Labs, Skunk Works, And The Crowd Sourcing Of Innovation

February 19, 2019 by 40 Comments

I’ve noticed that we hear a lot less from corporate research labs than we used to. They still exist, though. Sure, Bell Labs is owned by Nokia and there is still some hot research at IBM even though they quit publication of the fabled IBM Technical Disclosure Bulletin in 1998. But today innovation is more likely to come from a small company attracting venture capital than from an established company investing in research. Why is that? And should it be that way?

The Way We Were

There was a time when every big company had a significant research and development arm. Perhaps the most famous of these was Bell Labs. Although some inventions are inevitably disputed, Bell Labs can claim radio astronomy, the transistor, the laser, Unix, C, and C++ among other innovations. They also scored a total of nine Nobel prizes.

Bell Labs had one big advantage: for many years it was part of a highly profitable monopoly, so perhaps the drive to make money right away was less than at other labs. Also, I think, times were different and businesses often had the ability to look past the next quarter.

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Julius Lilienfeld And The First Transistor

December 11, 2018 by 31 Comments

Here’s a fun exercise: take a list of the 20th century’s inventions and innovations in electronics, communications, and computing. Make sure you include everything, especially the stuff we take for granted. Now, cross off everything that can’t trace its roots back to the AT&T Corporation’s research arm, the Bell Laboratories. We’d wager heavily that the list would still contain almost everything that built the electronics age: microwave communications, data networks, cellular telephone, solar cells, Unix, and, of course, the transistor.

But is that last one really true? We all know the story of Bardeen, Brattain, and Shockley, the brilliant team laboring through a blizzard in 1947 to breathe life into a scrap of germanium and wires, finally unleashing the transistor upon the world for Christmas, a gift to usher us into the age of solid state electronics. It’s not so simple, though. The quest for a replacement for the vacuum tube for switching and amplification goes back to the lab of  Julius Lilienfeld, the man who conceived the first field-effect transistor in the mid-1920s.

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New Transistor Uses Metal And Air Instead Of Semiconductors

December 3, 2018 by 59 Comments

The more things change, the more things stay the same. Early electronic devices used a spark gap. These have been almost completely replaced with tubes and then semiconductor devices such as transistors. However, transistors will soon reach a theoretical limit on how small they can be which is causing researchers to find the next thing. If the  Royal Melbourne Institute of Technology has its way, we’ll go back to something that has more in common with a spark gap than a conventional transistor. You can find the source paper on the Nano Papers website although the text is behind a paywall.

The transistor uses metal, but instead of a semiconductor channel — which is packed with atoms that cause collisions as electrons flow through the channel — the new device uses an air gap. You might well think that if fewer atoms in the channel are better, why not use a vacuum?

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Sidney Darlington

October 23, 2018 by 32 Comments

In a field where components and systems are often known by sterile strings of characters that manufacturers assign or by cutesy names that are clearly products of the marketing department and their focus groups, having your name attached to an innovation is rare. Rarer still is the case where the mere mention of an otherwise obscure inventor’s name brings up a complete schematic in the listener’s mind.

Given how rarely such an honor is bestowed, we’d be forgiven to think that Sidney Darlington’s only contribution to electronics is the paired transistor he invented in the 1950s that bears his name to this day. His long career yielded so much more, from network synthesis theory to rocket guidance systems that would eventually take us to the Moon. The irony is that the Darlington pair that made his name known to generations of engineers and hobbyists was almost an afterthought, developed after a weekend of tinkering.

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You Can’t Build A Roland TR-808 Because You Don’t Have Faulty Transistors

September 6, 2018 by 55 Comments

That headline sounds suspect, but it is the most succinct way to explain why the Roland TR-808 drum machine has a very distinct, and difficult to replicate noise circuit. The drum machine was borne of a hack. As the Secret Life of Synthesizers explains, it was a rejected part picked up and characterized by Roland which delivers this unique auditory thumbprint.

Pictured above is the 2SC828-R, and you can still get this part. But it won’t function the same as the parts found in the original 808. The little dab of paint on the top of the transistor indicates that it was a very special subset of those rejected parts (the 2SC828-RNZ). A big batch of rejects were sold to Roland back in the 1970’s — which they then thinned out in a mysterious testing process. What was left went into the noise circuit that gave the 808 its magical sizzle. When the parts ran out, production ended as newer processes didn’t produce the same superbly flawed parts.

This is an incredible story that was highlighted in 808, a documentary premiered at SXSW back in 2015. The film is currently streaming on Amazon Prime (and to rent everywhere else) and is certainly worth your time just to grasp how seminal this drum machine has been in hip hop and several other music genres.

For modern product developers, betting your production on a batch of reject parts is just batty. But it was a very different time with a lot fewer components on the market. What worked, worked. You do have to wonder how you stumble upon the correct trait in an obscure batch of reject parts? Looks like we’ll be adding Ikutar Kakehashi’s book I Believe in Music: Life Experiences and Thoughts on the Future of Electronic Music by the Founder of the Roland Corporation to our reading list.

[via EMSL]

Transistor Fundamentals Animated

September 2, 2018 by 5 Comments

When we were in school, every description of how transistors work was pretty dry and had a lot of math involved. We suppose you might have had a great instructor who was able to explain things more intuitively, but that was luck of the draw and statistically unlikely. These days, there are so many great videos on the Internet that explain things that even if you know the subject matter, it is fun to watch and see some of the great animations. For example [Sabin] has this beautifully animated explanation of how MOSFETs work that you can see below.

It uses the same basic graphics and style as his earlier video on bipolar transistors (second video, below) which is a great one to watch, too. In all fairness to your electronics teacher, the kind of graphics in these videos would have cost a fortune to do back in the 20th century — just watch some of the videos we talk about in some of our historical posts.

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Circuit VR: A Tale Of Two Transistors

August 17, 2018 by 8 Comments

Last time on Circuit VR, we looked at creating a very simple common emitter amplifier, but we didn’t talk about how to select the capacitor values, or much about why we wanted them. We are going to look at that this time, as well as how to use a second transistor in an emitter follower (or common collector) configuration to stiffen the amplifier’s ability to drive an output load.

Several readers wrote to point out that I’d pushed the Ic value a little high for a 2N2222. As it turns out, at least one of the calculations in the comments was a bit high. However, I’ve updated the post at the end to explore what was in the comments, and talk a bit more about how you compute power dissipation with or without LTSpice. If you read that post, you might want to jump back and pick up the update. Continue reading “Circuit VR: A Tale Of Two Transistors” →