Water Lock

[Like Ra]

Yes, agree about the ice locks. You never know how long it will take.

[Tinker D]

OK, I can see how that works. Good idea.
If you have the device, then you can have any water source with a valve that you can use to timed your release. The more you open the valve, the shorter the time. But make sure that there is a good drip. You wouldn't want something like one drip per hour to fill a 5-gal bucket.

[Strappado]

This looks very good and quite safe. And I also like the extra decorative work on the stand.

Since using water from a tap tends to be messy, it might be interesting to put the bucket on the other side of the beam, make a hole in the bottom and let it run dry. There should be a counterweight on the other side (where the bucket is on the original) to lift the rod when the bucket is empty.

I made a rough drawing.

   

Of course there should be another bucket underneath the bucket, to collect the water. And I think, it should be enough to make a hole in the base to keep the left rod in position until it is lifted.

The size of the hole in the bucket would determine the time until release. You could use various corks with different hole sizes to change it quickly.
A tap would work too, but is probably less predictable.

The advantage of this device is that the bucket will eventually run out of water. On the original device, if the water source or the device is misplaced by an accident, it won't ever release.