This commercial radio with 3 earphone listening transistors was manufactured in Japan in the 1960s. The medium-wave circuit uses germanium transistors and is powered by a 9 V battery.
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...