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