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.
This alarm circuit is from a 1990 Electronics Handbook. Transistor Q1 can be a BD135 and the relay...
This trigger circuit was found in old European documentation, but it can be implemented with...
This circuit is from the SGS Integrated Circuits Manual of 1982. The integrated circuit used is...