Minecraft

I am by no means good at redstone, so I do not know if my solution is compact or efficient (or any good at all!).

My approach is to make the pistons fire alternatively constantly until the string is not triggered for a few seconds then it stops firing the pistons. This way there is always a constant piston firing rate and after the last item has fallen through the string the pistons still fire a couple of times just in case some items fell on top of a slime block then this will clear the items.

In the images you can see I made a pulse extender coming off the observer that is looking at the string. Then there are observers looking at the dust that is part of the pulse extender and every time the pulse degrades the observers trigger. Then after those observers are repeaters to slightly extend the pulse so that the pistons fire slow enough not to leave their slime blocks behind.

Note that the repeater after the left observer is 3 ticks and the repeater after the right observer is 4 ticks.

OK, so here's the update. thanks to all the suggestions - I combined a few ideas, and came up with the following solution.

The observer triggers as items drop, this does two things at once:

1. Drives a pulse extender which immediately retracts the secondary piston
2. Pulses the primary piston after a short delay to push the items into the space that the secondary piston just made

As the clock decays fully the secondary piston fires and pushes the items.

An added bonus here is spam protection - so if items drop consecutively more quickly than the clock decays, it simply resets the clock so you don't get pistons firing together, or too quickly. This way nothing ever ends up on the top of the slime/honey blocks. I've added a front-side view for those curious as well.

Thanks for all the help and tips!

Which is supposed to be piston 1 or 2? They are labeled 2 and 3 in the image

I haven't done much MC Redstone in a long time (not in any significant way since some time observers were added). Couldn't you take the inverse signal for piston 2 and put it in an and gate to piston 1 (or vice versa). Basically make your circuit (p1/2 is piston 1/2) : p1= observer && !p2. p2 = delayed observer.

Edit: Actually, the delay might fuck this up. I don't know if I can help. It's been far too long. I don't have the intuition for it anymore.

what you could do is set piston 2 to be on an inverted signal from piston 1, instead of having a unique timing.

what this would do in effect is that piston 2 is extended by default, until an item passes in front of your observer, then piston 2 retracts and piston 1 extends, dropping the item in front of piston 2. and then when the pulse ends piston 1 retracts and piston 2 extends