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 the March 1980 issue of Radio Electronics magazine. It is based on the...
This circuit (2009) has driver control through the RTS signal or in automatic mode through the...
This monotone alarm oscillator circuit was found in July 1975 Radio Electronics magazine. Power is...