Just started T2 science in my run, and huge fun. The main issue I see is that there were a bunch of t1 techs that required.other techs to make use of, but didn't have prerequisites set. If they unlocked several things, some of which could be used it would be fine, but I tried to rush the synthesizer and recharger as obvious steps before realizing they were useless without, I think, circuits or widgets. Don't remember, this was last night. I Suggest adding such prerequisites so you don't have to memorize or check the recipes to know a tech is worthless until you do a tech-tree-wise unrelated tech.

In contrast, inserter tech unlocks the filter inserter, which doesn't work til you grab a few other techs, but since it unlocks usable inserters, it isn't as bad. Would still prefer it as a separate tech that requires circuit network tech though.

I'm a bit confused since I think Synthesizer already depends on the circuit and widget techs: https://imgur.com/a/Vl3z9h5 (same for the recharger).

Filter inserters could use their own tech if I can come up with appropriate technology graphics.

I'm confused now too. Because I wouldn't have made this post if there.wasn't something like this. Maybe it was rare metals? Or wires/circuits? Will check tonight when I get home.

On looking at it, you are correct, and I have no idea what issue I was remembering. My best guess is that either the Fast Splitter and Filter Inserters, which I immediately unlocked to automate the cube, before realizing you needed circuits/combinators, or else I ended up researching those components, but didn't have a rare metal mine yet. Though the latter case would not have pointed me at tech as the issue.

As suggestions, moving splitter to electronics tech, and filter inserter to the combinator tech might work if you don't have tech graphics available.