This circuit was published in an 80's American documentation, but it is still current. The power depends on the operational. The generated signal has a sinusoidal waveform.
This filter for the 300 Hz to 3 kHz range was found in an American documentation from the 90's....
The battery is charged by the photocell that keeps the low consumption beacon in the dark. The...
This is the typical circuit of an FET amplifier stage in the common source configuration. The circuit is...