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.
When the supply is established, the load only receives the supply some seconds later, a time that...
With S1 closed, when dark, the triac will supply the load with the power set in R4. The LDR is...
This interesting amplifier for frame antenna for the medium wave range was found in a Popular...