Minecraft - special redstone clock?

I'm looking for a special clock, not one that stops for a certain time but one that outputs exactly 13 signals. Can you help me?

Oh, I'm a redstone groundie.

Are you just concerned with the part giving a signal at 13 different times?

If so:

First the basic circuit:

Material:

1 redstone block

1 sticky piston

a few units of Redstone Dust

Structure (+ - | = Redstone Dust,> = Sticky Piston, # = Redstone Block):

+ → #
| |
+ - +

The principle: The redstone block activates the piston, which pushes the block to the side, which deactivates the piston and pulls the block back…

If you hang 13 redstone repeaters on it now, you have your 13 signals.

E.g. So:

+ → #
| |
+ - + - V-V-V-V-V-V-V-V-V-V-V-V-V
| | | | | | | | | | | | |

Possibly. You can also build the whole thing with 2 "normal" pistons, the last of which is only activated at the 13th signal and pushes the redstone block back to start the next run.