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.
The shunt type regulators are connected in parallel with the load, deflecting the current to...
Using the LM317 (or LM350), this circuit is based on precision regulatory components such as those...
This solar cell powered circuit generates a standard 100 kHz signal. The circuit is from a 1960...