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 project in a 2002 documentation. The transistor amplifier has a power of a few watts...
This circuit is from 1995 documentation. In the original, the source is symmetrical at 12 V, but...
Here we have a transceiver for the amateur radio range, which operates in the 40 m band (7 MHz),...