This simple audio and RF signal tracker was found in a Japanese publication in 1967. The transistors are made of germanium and the headphone is made of crystal.
This circuit is from the 1993 Motorola Linear Interface ICs. Equivalent operating may be used and...
Through the TTL output this circuit can be used as a shield. The sensor is a platinum probe, and...
This alarm with sensors in series and parallel was found in the 1995 Encyclopedia of Electronic...