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 suggested by Signetics in 1980s documentation. The circuit makes use of the...
This circuit produces low frequency sinusoidal signals. The circuit is a phase shift oscillator...
This variation of the previous circuit produces a pulsating sound when the sensor is activated. The...