How do you make the most compact rapid redstone pulser that never stops?

How do you make the most compact rapid redstone pulser that never stops?

And in my friend's server, the rapid redstone pulser stops after some time, and I have no idea why, how do you prevent that from happening?

There are 3 designs in mind:

and also this

The third design is slowest but it is also the smallest,

The problem with any always-on redstone design (including pulsars) is that they will die or glitch when no players are close enough to keep the chunk in memory. Redstone current is not saved with the world.

There are a couple of ways to combat this, both of which have been covered in previous questions here. You can either add a "jump-start" component to the circuit to get it started again after re-load or use a Bukkit mod to keep some chunks loaded regardless of player distance.

I know another way to make it far more compact see picture. If you power input it turns the pulser off (de-powering the input will make the pulser resume). to start it power and then de-power the piston. ta da! most compact pulser I have ever seen.