How do I use fade in on typewritter effect.

hey guys

I stumbled upon this great example capx of a typewriter effect (I think it was from Ashley).

https://www.dropbox.com/s/vgn4h9hptntq8is/typewriter.capx?dl=0

I just wonder, is there a way I can go a bit further and make it so each letter has a fade in effect when appears. Sort of like the following:

https://youtu.be/6IqxgBrgUzg?t=857

I tried whatever came to mind but can't seem to target each letter seperatly in any opacity operation that I can come up with.

Thanks guys

Cheers!