However although the "thread number" seemed to be the same (49993) it switched me to a discussion about water valves, titled "Looking for an electrically actuated water valve" (which actually seems to be thread 50046).
Then if I hit "previous" from page 2 of "Looking for an electrically actuated water valve" it takes me back to page 1 of "Logic Level MOSFET Question" (although the URL now says 50046).
This is just a feature of the forum software, hitting next takes you to the next thread. To navigate through pages of a thread you need to click the page numbers on the bottom left of the page.
Oh, right. How confusing. Can't it say "next thread"?
In any case, why does going from page 1 of thread A take you to page 2 of thread B? How useful is that? I mean, when reading about MOSFETs the discussion switches to "ball valves" when I hit "next" but it was on page 2 of the ball valves thread, with quotes and stuff, so it looked like I had just changed pages, until the context made me look back up to the forum title.
I simply can't think of a reason why you would want to jump from part-way in one thread to part-way in a different thread.
I am used to forums where to read through a thread you just hit a "next" button, otherwise you have to work out the current page, add one to it, and then find that number. Not too mentally taxing I know, but the "next" button saves you that trouble.