We found this circuit in the November 1992 Radio Electronics magazine. The circuit uses an LDR as a sensor and the transistor can be any general-purpose transistor.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...