How to make an energy condenser with two energy collectors while offline?

I've recently started to play tekkit classic again, I still know the basics and a little bit of the advanced knowledge but I have forgotten how to run a condenser while not having Minecraft launched on single player. I have tired putting the world anchor with the other glowing yellow bit that lets you choose how many chunks you load but it did not work, I put the two bits diagonally to each other and both on a one block lower level than the condenser, so maybe i need to put them on the same layer or put them side by side? I don't know, maybe I have to keep tekkit launched or the tekkit launcher up but i'm not sure, could someone please help, I'm running low on diamonds and I want it to still run so I can get off if i'm bored or when I don't know what to do.

Its simple really you take the first energy collector and then you take the second energy collector together and then boom there diamonds. Just be careful because i heard that someone did this the wrong way and spontaneously com-bust

To the best of me knowledge there's no way to run a single player world while you are not playing it.