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 alarm uses several sensors that directly trigger a sensitive relay. A larger relay can be...
This circuit was found in an old publicatio n from the year 1958. The circuit controls an external load by...
Found in the July 1994 Electronics Now magazine, this circuit drives a relay up to 12 V depending on...