"Simistor"?

[ozcar]

In another forum, somebody referred to an ST-made component, ACST6, as a "simistor", a term I had never heard of before. I don't feel totally ignorant though, as I note that even ST do not seem to use that name, preferring the long-winded "Overvoltage protected AC switch"  - https://www.st.com/resource/en/datasheet/acst6.pdf.

An old thread here hints that "simistor" could be derived from "symmetric thyristor", and by observation, Google seems to treat "simistor" as some sort of synonym of "triac", but such usage seems to be pretty rare. I also found that the term has been used for a completely different component, the "silicon thermistor" - https://www.theengineer.co.uk/silicon-thermistor/.

So, if somebody were to mention "simistor" to you, would you know what they were talking about?

[Zero999]

I've never heard of it. The data sheet is for a snubberless TRIAC. I presume it's a marketing term.

[wraper]

It's a triac. Triacs are called simistor in Russian. https://ru.wikipedia.org/wiki/%D0%A1%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80

[ColdPower]

When I went to school, the exact wording for triacs was "simistor" or the long version was exactly "symmetric thyristor". I guess maybe coming from Russian -

https://www.google.com/search?sxsrf=ALeKk03_nn1c7UZULvVcKPkEnjoFOcwy4w%3A1610912449941&source=hp&ei=wZIEYLC1N_TTgwfxx7XQDA&q=%D1%81%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80&oq=%D1%81%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80&gs_lcp=CgZwc3ktYWIQAzIFCAAQyQMyBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB4yBAgAEB46CwgAELEDEIMBEMkDOggIABCxAxCDAToICC4QsQMQgwE6AgguOgUIABCxAzoICAAQsQMQyQM6AggAOggILhDJAxCTAlDqCFjhD2CEEWgAcAB4AIABcIgB3gWSAQM2LjKYAQCgAQGqAQdnd3Mtd2l6&sclient=psy-ab&ved=0ahUKEwjwmd3C3KPuAhX06eAKHfFjDcoQ4dUDCAk&uact=5

[ozcar]

I've never heard of it. The data sheet is for a snubberless TRIAC. I presume it's a marketing term.

I'm glad to hear I'm not the only one to be unfamiliar with it. It was not obvious that ST had used it as a marketing term, but maybe I missed that.

It's a triac. Triacs are called simistor in Russian. https://ru.wikipedia.org/wiki/%D0%A1%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80

I'll have to take your word that "simistor" is mentioned there, as I don't know how that would be written.
 

[wraper]

I'll have to take your word that "simistor" is mentioned there, as I don't know how that would be written.

Put into google translate and let it sound. https://translate.google.com/?sl=ru&tl=en&text=%D0%A1%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80&op=translate

[RoGeorge]

Triac.

[S. Petrukhin]

It's a triac. Triacs are called simistor in Russian. https://ru.wikipedia.org/wiki/%D0%A1%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80

Maybe I'm wrong, but the simisеor is not only a russian name, it is an international name for two counter-connected thyristors with a common control input. Triac has a different structure. 3Q, 4Q...

[ozcar]

Maybe I'm wrong, but the simisеor is not only a russian name, it is an international name for two counter-connected thyristors with a common control input. Triac has a different structure. 3Q, 4Q...

If that spelling was intentional, it defeats both Google and Bing, quite an achievment!

"Semistor" ( a suggestion from Mrs Ozcar, who did a course of Russian translation half a century ago), seems more promising...

[RoGeorge]

In the datasheet linked in the OP it is described as a triac https://www.st.com/resource/en/datasheet/acst6.pdf and it might be described as a diac with a gate (my guess), but the name of simistor is mostly unknown.

[wraper]

it is an international name for two counter-connected thyristors with a common control input.

Such part does not exist AFAIK and would not work to begin with. You cannot simply connect gate terminals together.

[ColdPower]

it is an international name for two counter-connected thyristors with a common control input.

Such part does not exist AFAIK and would not work to begin with. You cannot simply connect gate terminals together.

Incidentally, that is the triac's "simistor" equivalent circuit, isn't it 

[S. Petrukhin]

it is an international name for two counter-connected thyristors with a common control input.

Such part does not exist AFAIK and would not work to begin with. You cannot simply connect gate terminals together.

There are thyristors that are controlled not relative to the cathode, but relative to the anode. 

[ozcar]

Put into google translate and let it sound. https://translate.google.com/?sl=ru&tl=en&text=%D0%A1%D0%B8%D0%BC%D0%B8%D1%81%D1%82%D0%BE%D1%80&op=translate

I just noticed that getting that to say "triac" results is something like "tree-ack", which is not how I say it. What next, tree-angles? So, not sure that is very trustworthy.

Thanks for all the comments, I'll have to put this down as yet another of the many things I did not know. Or, if perchance I did know it, I had forgotten, an increasingly common phenomenon.

[VK3DRB]

I've never heard of it. The data sheet is for a snubberless TRIAC. I presume it's a marketing term.

SIDACtor... just a TVS with a marketing term that makes it fantastic.