Category Archives: transistor

Help Solve The Single-Transistor Latch Mystery

If you’ve spent any time on hackaday.io, you may have noticed that more than a few denizens of the site are fans of “alternative” electronic logic. Aiming to create digital circuits from such things as relays, vacuum tubes, discrete transistors, and occasionally diodes, they come up with designs that use …read more

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Retrotechtacular: How Not to Design With Transistors

Consider the plight of a mid-career or even freshly minted electrical engineer in 1960. He or she was perched precariously between two worlds – the proven, practical, and well-supported world of vacuum tube electronics, and the exciting, new but as yet unproven world of the transistor. The solid-state devices had …read more

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Posted in comparative, design, electrical engineering, electron tube, Hackaday Columns, Retrotechtacular, transistor, vacuum tube | Leave a comment

Bell Labs, Skunk Works, and the Crowd Sourcing of Innovation

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 …read more

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Posted in bell labs, Business, Featured, history, ibm, lockheed, Nobel, rants, skunk work, skunk works, transistor, Volta | Leave a comment

New Transistor Uses Metal And Air Instead Of Semiconductors

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 …read more

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

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 …read more

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Posted in drum machine, Ikutar Kakehashi, musical hacks, noise, noise circuit, roland, Roland TR-808, TR-808, transistor | Leave a comment

Circuit VR: A Tale Of Two Transistors

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 …read more

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Posted in bipolar transistor, circuit vr, common collector, common emitter, emitter follower, LTSpice, Skills, spice simulation, transistor | Leave a comment

Circuit VR: Starting an Amplifier Design

Sometimes I wish FETs had become practical before bipolar transistors. A FET is a lot more like a tube and amplifies voltages. Bipolar transistors amplify current and that makes them a bit harder to use. Recently, [Jenny List] did a series on transistor amplifiers including the topic of this Circuit VR, the common emitter amplifier. [Jenny] talked about biasing. I’ll start with biasing too, but in the next installment, I want to talk about how to use capacitors in this design and how to blend two amplifiers together and why you’d want to do that.

But before you can dive …read more

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Biasing That Transistor Part 4: Don’t Forget the FET

Over the recent weeks here at Hackaday, we’ve been taking a look at the humble transistor. In a series whose impetus came from a friend musing upon his students arriving with highly developed knowledge of microcontrollers but little of basic electronic circuitry, we’ve examined the bipolar transistor in all its configurations. It would however be improper to round off the series without also admitting that bipolar transistors are only part of the story. There is another family of transistors which have analogous circuit configurations to their bipolar cousins but work in a completely different way: the Field Effect Transistors, or …read more

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Biasing That Transistor: The Emitter Follower

We were musing upon the relative paucity of education with respect to the fundamentals of electronic circuitry with discrete semiconductors, so we thought we’d do something about it. So far we’ve taken a look at the basics of transistor biasing through the common emitter amplifier, then introduced a less common configuration, the common base amplifier. There is a third transistor amplifier configuration, as you might expect for a device that has three terminals: the so-called Common Collector amplifier. You might also know this configuration as the Emitter Follower. It’s called a “follower” because it tracks the input voltage, offering …read more

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Circuit VR: Current Mirrors

Last time we looked at Spice models of a current sink. We didn’t look at some of the problems involved with a simple sink, and for many practical applications, they are perfectly adequate. However, you’ll often see more devices used to improve the characteristics of the current sink or source. In particular, a common design is a current mirror which copies a current from one device to another. Usually, the device that sets the current is in a configuration that makes it very stable while the other device handles the load current.

For example, some transistor parameters vary based on …read more

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