This circuit is from an old Mullard (Philips) manual with applications using the 555. Choosing appropriately the resistors and the timing capacitors, the ranges obtained can exceed days.
This circuit was found in a 1975 documentation. The SCR can be of any type and in this case, we...
This fuzz circuit is more elaborate with the previous ones, as it has a selection switch that...
The XR2206 is not a common component today, but if you have one you can build this function...