Thyristors control

[ze]

Hi
does anyone know any circuit that allow me to change the frequency of pulse that will act in a thyristor gate?
i need to control the output current of a thyristor and the guess that it can be done if i can change the number o times that the thyristor guets an impulse. is that correct?
thanks :?:

 

[Phasor]

By "thyristor", I'm guessing you mean an SCR. "Thyristor" refers to a whole family of devices, including SCRs, Triacs, Diacs, PUTs, GTOs etc.

You will have to give us more details of your circuit and application, in order to answer your question properly.

Remember that an SCR, once triggered, maintains current flow, until the anode current is reduced to near zero by some other means. What is there in your circuit to interrupt the current?

 

[ze]

thanks for your reply
in the rectifier thers is a transformer and conected to the primary of the tranfrmer there are 2 scr in oposition that control me the output current of the rectifier, what i need to do is to do this automatialy, so i will need to control the scr firing angle right? and this firing circuit will be conected to a PLC
did i explain in the right way?
thank you

 

[Nigel Goodwin]

thanks for your reply
in the rectifier thers is a transformer and conected to the primary of the tranfrmer there are 2 scr in oposition that control me the output current of the rectifier, what i need to do is to do this automatialy, so i will need to control the scr firing angle right? and this firing circuit will be conected to a PLC
did i explain in the right way?
thank you

Perhaps you ought to post the circuit?.

 

[ze]

sorry but i don't understand "ought" !
not even the dictionary has that word!
do you think it's possible to built one of these boards or it's best to look in the internet for some pre-built?

 

[Nigel Goodwin]

sorry but i don't understand "ought" !
not even the dictionary has that word!

It spell checks fine!.

Presumably English isn't your first language?, but as you haven't entered your location we've no way of knowing.

Anyway, I'll try the question again!.

Perhaps you should post the circuit.

 

[ze]

Yes, you presume well! English is not my first language, not even the second!!
that kind of circuit was what i was trying to find out!
i searched in the internet for this kind of circuits, and i saw many companies that sell this boards, so i reached a conclusion, it's not easy to built one of these circuits right?
I'm sorry for my lack of knowledge, but new in this bussines and there are a lot of things that i dont know, that's why i joined this forum, to achieve more knowledge.

 

[Nigel Goodwin]

Yes, you presume well! English is not my first language, not even the second!!
that kind of circuit was what i was trying to find out!
i searched in the internet for this kind of circuits, and i saw many companies that sell this boards, so i reached a conclusion, it's not easy to built one of these circuits right?

Your English is actually quite good, although your spelling is a little poor. But the English itself is good enough not to make it obvious that it's not your first language (never mind your third!).

But your actual requirements are still rather vague (not clear), which is why I suggested you post a circuit diagram (schematic) showing what you wish to do.

For a start, are you wanting to just turn a thyristor ON and OFF, or do you want to vary the power with it?.

 

[ze]

I atach a paint file where it's better explained want i want to do!
i want to control the output current on my retifier, as far as i know it is possible by vary. the firing angle of the scr's right? what do you think??

 

[Sebi]

UAA145 designed for this purpose...

 

[ze]

thanks Sebi!
this component it is to control the scr's right?

 

[Sebi]

Yes, i've used it for same application: controlled rectifier for 10A analog supply.