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 appears elsewhere on this site using the most diverse transistors. This version is...
Frequency in this oscillator is controlled by a crystal. Any 1 MHz to 15 MHz can be used. The JFET can...
This was one of the National Semiconductor clock modules very popular in the 70s and 80s. In the...