This Japanese radio is from the 60s, presenting excellent sensitivity and an output power of 100mW with 6 V power from ordinary batteries. The circuit is of the superheterodyne type.
This simple alarm circuit was found in a 1998 documentation. When the sensors are activated, the...
This circuit was found in an old American documentation. The integrated circuit used is uncommon...
Found in a 90s Electronic Design, this suggestion to have a higher voltage in a fixed regulator...