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.
We found this circuit in a year 2000 documentation. It must be powered by a voltage of 5 V as it...
This circuit was found in the February 1990 issue of Radio Electronics magazine. The circuit uses...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...