Talk:TRIAC

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Gates[edit]

The details begin with "gate", and it appears as if there is only one gate at first. But then, in the descriptions and examples that follow, there suddenly appears to be two different gates - namely "gate 1" and "gate 2". So, the newcomers would be confused. How many gates are there for a triac? One? Two? Furthermore, the illustrations appear to be erroneous, in that the quadrant 3 diagram says "gate 2 negative", but the diagram currently has the "gate" on MT1 (Main Terminal 1). A similar issue for the quadrant 4 diagram, which says "gate 1 positive", but the "gate" is connected to MT2 according to the quadrant 4 diagram.

Those diagrams also shows four (not three) nodes. So why show four nodes when triacs are generally sold with three pins? — Preceding unsigned comment added by KorgBoy (talk • contribs) 09:33, 12 December 2016 (UTC)[reply]

I think I can help here. All of these devices have 4 or more layers and a nominal Cathode / Anode arrangement. In an SCR the "gate" is the base of one of the virtual transistors nearest the Cathode. In an SCS, both "gates", or the bases of both virtual transistors, is brought out at both the Anode and Cathode. In a PUT, the "gate" is the base of the virtual transistor nearest the Anode. In this case, there are two more PN junctions, creating two more virtual transistors as well as a fifth virtual transistor at the "gate". In the introductory schematics, the diagrams are the same, but inverted. The "gate" is the same terminal whether named "gate 1" or "gate 2". I'd recommend putting a caption on the diagrams in that section to clarify the inversion and removing the "1" and "2" from the "gate" designation. 50.247.247.81 (talk) 14:54, 19 September 2017 (UTC)[reply]


The drawings make no sense any way you turn them. It is written gate+/gate- and an `equivalent` circuit with transistors are shown, but the equivalent circuit has more pins than a triac does... It is also not mentioned in respect to what the gate is + or -. Voltages always require two points. Have a look at this pdf from ST and you will quickly see how confusing the image given in the wiki is. https://www.st.com/content/ccc/resource/technical/document/application_note/ce/e4/e4/c5/d3/bf/4c/c7/CD00003868.pdf/files/CD00003868.pdf/jcr:content/translations/en.CD00003868.pdf

After reading the wiki it is not even remotely possible to deduce that a triac could be controlled as shown in the st pdf. — Preceding unsigned comment added by 2A02:810B:4C0:66F6:A64C:C8FF:FE1C:9E42 (talk) 02:32, 3 March 2019 (UTC)[reply]


I agree with the objections above. Figure 1 doesn't make sense: neither is it correlated to the triggering mechanisms presented in the "Operation" section, which can be verified for instance in source [2], nor is it consistent with other literature, such as the AN https://www.st.com/content/ccc/resource/technical/document/application_note/ce/e4/e4/c5/d3/bf/4c/c7/CD00003868.pdf/files/CD00003868.pdf/jcr:content/translations/en.CD00003868.pdf.

Therefore, I am going to revert this figure to the following one, which I originally posted 8 years ago and was found in this article as late as this article's revision https://en.wikipedia.org/w/index.php?title=TRIAC&direction=prev&oldid=503427601.

It looks amazing to me that a wrong picture has remained on this article for such a long time. Vitaltrust (talk) 08:54, 2 November 2019 (UTC)[reply]

As the author of the diagram you removed, and as the electronic engineer who has extensively used these devices and physicist who researched these at the quantum level, I can state that the diagram is an obvious extension of the "equivalence curcuit" presented in quandrant 1.

So please be far less subjective in your criticism. It would help if in the spirit of wikpedia you improved it instead of replacing it with a meaningless image table of not real use to anyone who is attempting to understand these devices. Grahamatwp (talk) 20:43, 2 February 2021 (UTC)[reply]

For what it's worth, I find the removed illustration perfectly sensible, useful, and indeed obvious, and I see no reason to remove it. It is quite clear from Figure 2 that the two gates (one being N-type and one P-type) are in fact shorted together.

(...) the quadrant 3 diagram says "gate 2 negative", but the diagram currently has the "gate" on MT1 (Main Terminal 1). A similar issue for the quadrant 4 diagram, which says "gate 1 positive", but the "gate" is connected to MT2 according to the quadrant 4 diagram.

I don't see any place in the diagram where gate (whether "gate 1" on the left or "gate 2" on the right) is connected to a main terminal.

After reading the wiki it is not even remotely possible to deduce that a triac could be controlled as shown in the st pdf.

I assume this was coming from someone who failed to realize that there is in fact only a singe gate (and thus the TRIAC is a three-terminal device), and the two gates are connected together. Once you manage to understand this, such "deduction" should be quite straightforward. 90.183.96.145 (talk) 01:02, 8 January 2023 (UTC)[reply]

TRIAC patent[edit]

Hi to all, I found this link: http://patentimages.storage.googleapis.com/pdfs/US3275909.pdf US Patent 3 275 909 by Frank W. GUTZWILLER Filled on Dec./19/ 1963 Patented on Sept.27 1966 92.152.102.56 (talk) 15:14, 15 April 2017 (UTC)link found by Jacky THIELLIN -France [1][reply]

References

  1. ^ http://patentimages.storage.googleapis.com/pdfs/US3275909.pdf

Other names[edit]

Symistor--Юе Артеміс (talk) 13:00, 16 March 2018 (UTC)[reply]

Triacs aren't used for induction motors[edit]

Article indicates triacs can be used to control speed of induction motor. Though one might be able design a circuit that does this to prove a point, one cannot (generally speaking) control the speed of an induction motor by adjusting the voltage it gets. Torque, maybe. But to control speed you need to control frequency, not voltage, and lowering voltage under load usually leads to overheating. Reference to induction motor should be replaced with brushed ac or "universal" motor. The wiki article for universal motors affirms that an advantage of such motors is easy speed control via triac. — Preceding unsigned comment added by 73.162.24.160 (talk) 07:17, 7 March 2019 (UTC)[reply]

Triacs don't control voltage, but instead timing of turning it on. (Off at the next zero crossing.) As far as I know, it is more usual to use SCRs for big motor control as the current is higher. There is a favorite circuit for controlling a universal motor with an SCR, which uses the back-EMF to control the SCR triggering. TRIACs are an old favorite for light dimmers, though. Gah4 (talk) 23:18, 2 February 2021 (UTC)[reply]
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