need help selecting the right optocouple

[jbest]

their is a seperate resistor to each optocouple

the statment you said were they will turn on a different increments depending on the resitance from the source is that called phase angle latching

all the scr outputs are hooked together and go to the load as one

the circuit is varible transformer 5amp and is hooked to an inductive load

i am guessing to acheive a side by side wave i will have to try different resistors on the k side of the scr like you said also would mounting each scr with its own power source instead off them all on one strip help to give me the 4 hump 50htz wave like in the first drawing

is their a type of mosfet that will give me a rounded top similar to what i had draw in the diagram ? like something used in a sinewave inverter

thanks for the help so far tonigua

 

[tonigau]

I don't see why you need 4 SCR's, it could be done with just one (unless I am misunderstanding)
Your square wave signal (1khz) is going into the 7404, then buffered by 4 other gates (all in phase) & fed to 4 optocouplers turning on all 4 SCR's at the same time.

i am guessing to acheive a side by side wave i will have to try different resistors on the k side of the scr

No, resistors on the "K" leads are only for equalising current in parallel scr's
But I suspect you are not paralleling the SCR's for added current, rather to get a sequential control ???, so the equalising resistors would be irrelevent.

If you just want 4 "humps" at 50hz set your square wave to 35ms (30ms for 60hz) but you will need ZCD (Zero Crossing Detect) so the SCR turns on at the start of first "hump" & turns off before the 4th "hump"
See atached gif.
There would be other ways to do this...

Should start a new thread for this one.


In your drawing you stated "what I am trying to make" & the graphic is a 1khz burst modulated full wave DC with the original half wave waveform below.
You cannot do this with an SCR. (Unless I am musunderstanding your intentions here as well).

Keep in mind the current rating for the SCR's is with a suitable heatsink.

The big question: What are you trying to do, what actually is your load.


Tonig.au

 

[jbest]

i was trying to take this pulse train and put it thru an inductor to cause transient spike forming a huge igniton coil

the attachment didnt take can you please repost it

thanks for your help tonigua

 

[tonigau]

the attachment didnt take can you please repost it

This has happened a few times, try right clik & save as. (it worked when I did this)

Might be a bug in electrotech? / explorer ?

I have tried before to re-attach but stays the same, I will save as different format that should fixit

 

[tonigau]

Heres a pdf for the 4wave DC phase control...

 

[jbest]

thanks for the pdf

i quess i will have to reevaluate what im doing and play with the circuit tommorow and see what im going to end up doing

thanks for the help tonigua

 

[jbest]

tonigua i think i figured out were my circuit went wrong i was searching thru scr phase control and i came across this pdf on it about half way down on the left is a section on scr with ttl

according to this my error is i didnt grond the electronic circuit to the ground of the power circuit

i found the problem i dont have the circuit set up as a bridge rectifer circuit

i will have to try this tommorow

 

[jbest]

tonigua i found the problem i can make the wave shown i just didnt have the scrs set up right i need to make a bridge rectifier out of it as in the pic

 

[tonigau]

according to this my error is i didnt grond the electronic circuit to the ground of the power circuit

With this approach you are more likely to electrocute yourself than get the circuit working the way you want. Better to reference example in "Figure AN1003.22" on the same page.


Variacs can be especially dangerous as if there is a wiring fault (A/N reversed) there will be full mains Voltage to earth even if the variac output is 10V.


---------------------------------------------------------
James,
I dont think this discussion thread is going to resolve your needs not in the short term anyway, & I am getting a bit dizzy .

Try & find an example of how someone else has made a circuit that will do the same/similar as your desired result.

I would suggest buying some electronic reference books or read some online tutorials, you need to have a sound basic understanding of the parts & how they operate/interact to achieve a good result.

Datasheets & application notes are also a valuable source of information but having base knowledge will make these documents more useful.

When you have gained some more kniowledge you then only need to ask a few key questions to get something working properly.

Good luck.

Toni g .au

 

[jbest]

thank for the help tonigua it was extremly helpfull and lead me to the info i needed to finish