Talk:Bipolar junction transistor

reverse active mode

The article indicates that reverse active mode is seldom used. In most types of circuits, I expect that is true, but it is an important part of the operation of TTL circuits. Specifically, the advantage of TTL over DTL. As TTL is getting less common, and CMOS more, I suppose it is less common than it used to be, but still not so seldom. Gah4 (talk) 07:54, 29 March 2020 (UTC)

Why is there a random formula for $J_{n}({\text{base}})$

This formula in the Ebers Moll model section comes out of nowhere. $J_{n}({\text{base}})$ doesn't appear in any formula and nothing explains what base internal current is. I can't fix it because I do not know.

$J_{n\,({\text{base}})}={\frac {1}{W}}qD_{n}n_{bo}e^{\frac {V_{\text{EB}}}{V_{\text{T}}}}$

2600:8807:5480:713:EC68:B0E5:991B:BFAC (talk) 00:05, 25 May 2020 (UTC)

Propose removal of "Technical" tag (on section "Function") dating from 2012

The "Technical" tag on this section of the BJT article does not seem to apply any longer; for example, many inline citations now exist, leading directly to Wikipedia articles that explain the concepts involved. I have read the section and do not see the need for this tag at this date; also, the Talk page does not contain much discussion of this issue, and certainly nothing that can be decribed as "active".

As the BJT is a complex system, there will be a need to use technical terminology in explaining it. This is no different from any other advanced/non-introductory concept and does not (in my opinion) warrant a tag "in-and-of itself". I do believe a few tweaks/improvements can still be made (and am happy to make them), however I believe the "Technical" tag has served its purpose in the last decade and is no longer needed.

I am raising the issue here to see if anyone has strong feelings about this, and also if anyone is willing to help with improvements. Snooze Dogg (talk) 12:34, 27 July 2022 (UTC)

Removing the tag is much easier than fixing the article. But have we really done all we can to make the presentation more accessible, or is it infested with relativistic effects, excess math typesetting, and spurious ISO standards? --Wtshymanski (talk) 02:20, 14 August 2022 (UTC)

I vote for removing it. Removing it doesn't say that the article is perfect, as no article ever is. With {{cn}}, we usually know we can remove it when we supply a (hopefully good enough) citation. In this case, the line is fuzzier. There is no completely untechnical explanation of a bipolar transistor. (There might almost be for a MOSFET.) If the article is within the range of the usual article on a technical subject, I think we can remove it. Gah4 (talk) 12:14, 15 August 2022 (UTC)

Proposed summary for technical prose

I've been using Google's Gemini 2.5 Pro Experimental large language model to create summaries for the most popular articles with {{Technical}} templates. This article, Bipolar junction transistor, has such a template in the "Function" section. Here is the paragraph summary at grade 5 reading level which Gemini 2.5 Pro suggested for that section:

A bipolar junction transistor, or BJT, is a tiny electronic part with three connections called the emitter, base, and collector that controls electricity. Think of it like a faucet where the base is the handle: a small signal sent to the base controls a much bigger flow of electricity between the emitter and the collector. This lets the BJT make weak electrical signals stronger or act like a switch to turn bigger currents on and off.

While I have read and may have made some modifications to that summary, I am not going to add it to the section because I want other editors to review, revise if appropriate, and add it instead. This is an experiment with a few dozen articles initially to see how these suggestions are received, and after a week or two, I will decide how to proceed. Thank you for your consideration. Cramulator (talk) 13:13, 2 April 2025 (UTC)

I think what we already have is much better. The voice is not encyclopedic. In STEM articles, we try for grade 9 reading level. Some BJTs are large. Those on integrated circuits actually have four connections, the fourth being the substrate. Constant314 (talk) 13:49, 2 April 2025 (UTC)

I picked fifth grade because I had been told or read long ago that the World Book Encyclopedia is written at that level. I will gladly re-run these suggestions at grade 9 and fold them in as alternatives. I see what you mean about the substrate being a physical connection, although I think it's usually composed of an insulator. Cramulator (talk) 14:40, 2 April 2025 (UTC)

The substate connection to BJTs usually a parasitic reverse biased diode, which leads to unexpected failure mechanisms. There is dielectric isolation, but that is more expensive. Constant314 (talk) 14:55, 2 April 2025 (UTC)

For most of the years when BJT integrated circuits played a large role, especially in computers, the substrate connection was a reverse-biased diode, and that was the only way known to build them. This lasted from the 1960s through the early 1990s. In the mid to late 1990s insulating substrates were developed, but this required major changes to manufacturing processes, and only a few fabs adopted it. By the early 2000s CMOS had almost entirely displaced BJTs. Jc3s5h (talk) 15:31, 2 April 2025 (UTC)

The level of the generated passage is the kind of level one might put in the lead. It has no place in the more detailed sections of articles like this one. It reminds me of the time our electrical engineering class at USC made a field trip to the Sylmar Converter Station and the representative from the electric utility who met us told us he was expecting a group from a grade school. Jc3s5h (talk) 15:34, 2 April 2025 (UTC)

Here is the ninth grade reading level summary for this article:

A Bipolar Junction Transistor (BJT) is an electronic switch or amplifier with three parts: the emitter, base, and collector. It comes in two types, NPN and PNP, based on how materials are layered. BJTs work by using a small electrical current or voltage at the base terminal to control a much larger current flowing from the emitter to the collector. For this to happen, the connection between the base and emitter is usually turned "on" (forward-biased), allowing charge carriers (like electrons) to flow from the emitter into the very thin base region. Most of these carriers then travel across the base and are collected by the collector, which has its connection to the base turned "off" (reverse-biased). The thinness of the base is crucial because it allows most carriers to reach the collector without getting lost, enabling the transistor to amplify the small base signal into a large collector current.

I would love to know what you think of it. To be honest, I really do prefer the simpler one, even for the Function subsection. The reason is that I spent most of my teens trying to learn electronics from books that were too advanced for me, while unable to find anything intermediate or advanced that used metaphors I could understand. (I was stuck in a rural area with small libraries before the internet.) Maybe we should see what happens requesting seventh grade level prose. Cramulator (talk) 16:30, 2 April 2025 (UTC)

Have you considered Simple English Wikipedia? Constant314 (talk) 20:18, 2 April 2025 (UTC)

Indeed. Sadly, when second grade students type or say words into Google and the other popular search engines, they are shown links to Wikipedia, not the Simple version. Are you writing for the audience you have or the audience you imagine you have? Cramulator (talk) 16:37, 3 April 2025 (UTC)

• That ninth grade one is a terrible description, in that it fails to explain anything. It's typical LLM output (and TBH, WP suffers from this too) in that it's perfectly correct [sic] yet it's also failing because it has no editorial narrative. There's no overall structure behind the words, even if the words in isolation are good.

The description (as broadly here) needs to state three things: they're three-legged devices which can make amplifiers, they come in NPN and PNP flavours, and they respond to a small change in an applied control current at the base controlling a much larger output current through the collector. We don't need to explain how it works in the same paragraph and we don't need to talk about charge carriers. The same article does, but not the same section. Also saying anything about base voltage is somewhere between wrong and badly misleading. Andy Dingley (talk) 21:01, 3 April 2025 (UTC)

Use of LLM needs to be discussed by the entire Wikipedia community, not just those interested in one article. You can start at WP:Village pump. Sundayclose (talk) 15:25, 2 April 2025 (UTC)

I am retracting this and the other LLM-generated suggestions due to clear negative consensus at the Village Pump. I will be posting a thorough postmortem report in mid-April to the source code release page. Thanks to all who commented on the suggestions both negatively and positively, and especially to those editors who have manually addressed the overly technical cleanup issue on six, so far, of the 68 articles where suggestions were posted. Cramulator (talk) 01:52, 5 April 2025 (UTC)

Thanks for making the effort to improve Wikipedia and thanks for taking the negative response in good humor. I look forward to your postmortem report. Constant314 (talk) 02:53, 5 April 2025 (UTC)