thyristor vs triac

[cjdelphi]

I'm posting this mainly for others, but after a few searches and ebay seller listings many people seem confused...

While looking for resources to read, most people seem to interchange or use both "triac" and "thyristor" like they are both the same component!

And to add to confusion "SCR" well a sillicon controlled rectifier can be a triac or thyristor right?

In short thyristors allow ac to flow in 1 direction, triacs allow ac to flow in both directions, search for thyristor circuits and you'll indeed find triacs not thyristors but a lot of people seem to confuse the two which confused me lol

 

[Minder]

Both the GE SCR manual and the RCA manuals both refer to Triacs (bidirectional triode thyristor) and SCR's as part of the Thyristor family of semiconductors.
M.

 

[Tha fios agaibh]

Basically, SCRs and thyristors are for switching dc and triacs for switching ac.
A believe "thyrisor" is just a fancy name for a high current SCR.

So a triac and a thyristor are not the same components, but a scr and a thyristor are essentially the same.

 

[Minder]

So a triac and a thyristor are not the same components, but a scr and a thyristor are essentially the same.

GE were the first developer of the Triac after the SCR development (patent 3,275,909), and they termed it a Bidirectional Triode Thyristor.
I have the 6th edition of the GE SCR manual, 1st edition 1st pub. 1958.
They refer throughout to SCR's and Triacs as thyristors devices.
M.

 

[Tha fios agaibh]

They refer throughout to SCR's and Triacs as thyristors devices.
M.

Thank you for the correction.
I have never heard anyone referring to a Triac calling it a Thyristor.

 

[dorke]

What's in a name?

Before the semi-conductor period,
"name calling" started with Vacuum-Tubes or Valves.
As in so many fields we have the Greecks to blame for

They where named by the number of the Electrodes :
DIODE : DI-ODE ,Di for dual or 2 ,ODE short of electrode
TRIODE : TRI-ODE ,Tri for 3
TETRODE : TETR-ODE ,Tetr for 4
PENTODE : PENT-ODE ,Pent for 5

Then there were the ones named by "functionality"
MAGNETRON :Magne-Tron ,Magne for magnet,Tron for Electron.
CYCLOTRON :Cyclo-Tron, Cyclo for cycle (circle)
THYRATRON :Thyra-Tron ,Thyra for entrance or gate.

then came the semis named as follows:

THYRISTOR :Thyr-Istor ,replacing Tron(from Thyratron above) with Transistor (Thyra+Transistor)

TRIAC Tri-AC : TRi for 3 pins ,AC for Alternating Current

DIAC Di-AC : Diode for AC

S.C.R Silicon Controlled Rectifier a controllable diode( for DC).


Personally,
I prefer not to use Thyristor and prefer
SCR for DC and Triac for AC.

 

[Minder]

S.C.R Silicon Controlled Rectifier a controllable diode( for DC).


Personally,
I prefer not to use Thyristor and prefer
SCR for DC and Triac for AC.

A Triac If used on DC has to be commutated off, they are just as readily used in AC such as SCR bridge for one etc.?
Also SCR used back to back for AC use to simulate a triac.
I guess those that develop them, get to name them.
M.

 

[Tha fios agaibh]

Seem silly to me to use generic names like thyristor or vacuum-tube when referring to components.

It's like walking into a grocery store and asking for a can of vegetables.

 

[dorke]

A Triac If used on DC has to be commutated off, they are just as readily used in AC such as SCR bridge for one etc.?
Also SCR used back to back for AC use to simulate a triac.
I guess those that develop them, get to name them.
M.

Absolutely,
SCRs are used in AC application.

The inventors do it lovingly like naming a new born baby...

 

[dorke]

Seem silly to me to use generic names like thyristor or vacuum-tube when referring to components.

It's like walking into a grocery store and asking for a can of vegetables.

Well ,
Imagine asking for a "Modern Aladdin's Lamp"
here goes a true gem,enjoy

 

[Tha fios agaibh]

Those confounded newfangled inventions. Lol

(Good video but could only stand about 5 minutes of it)

 

[sureshot]

I thought a triac was two thyristors back to back in a single package ?

 

[dorke]

Those confounded newfangled inventions. Lol

(Good video but could only stand about 5 minutes of it)

The interesting part stars after 5:00...

 

[Herschel Peeler]

Thyristor is a general group of transistors that includes SCRs TRIACs, SCSs and such.

 

[cjdelphi]

Thyristor is a general group of transistors that includes SCRs TRIACs, SCSs and such.

À SIlicon Controlled Rectifier (SCR) is going back to William Shockleys 4? Layer diode is a general group of transistors but a thyristor and triac are not the same thing even though they're both SCRs

 

[PAFMElb]

Basically, SCRs and thyristors are for switching dc and triacs for switching ac.
A believe "thyrisor" is just a fancy name for a high current SCR.

So a triac and a thyristor are not the same components, but a scr and a thyristor are essentially the same.

Can't agree with that.
An SCR is a thyristor. A Triac is a thyristor. SIDACs, DIACs, SBSs (Silicon Bilateral Switch) and PUTs* (Programmable Unijunction Transistor) are also usually considered in the thyristor family.

In general thyristor refers to any 4 layer semiconductor with a negative resistance characteristic. Often the term thyristor is (incorrectly) used as a synonym for a Silicon Controlled Rectifier (SCR). So... An SCR is always a thyristor, but a thyristor is not necessarily an SCR.

*Note that a PUT is waaayyy different from a true Unijunction Transistor (UJT). Totally different technologies. It just happens that PUTs are (were?) used as a replacement for true UJTs because their behaviour when used in trigger circuits was similar.

 

[Minder]

Thought we had put this one to bed 5 years ago?

 

[bertus]

Hello,

Have a look at the attached PDF and PDF in the link made by ON:
https://github.com/Miceuz/triac-bloc/raw/master/HBD855-D.pdf

Bertus