This is a Japanese commercial radio from the 60s. The superheterodyne circuit of 7 transistors for medium waves has 200mW of output when powered by 4 common batteries.
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...