This receiver for the AM band with 6 transistors was manufactured in the 60's in Japan. The power is made with 9 V and the circuit is of the super heterodyne type with FI of 455 kHz.
If you have a disused old computer, the type that still has a parallel port, you can use it in...
This circuit triggers on a lamp when the sensor (a metal plate us touched). Up to 100 W...
Suggested by National based on the LM6218, this circuit from the 90s has high speed...