This sensitive two-transistor circuit was found in the June 1965 Radio Electronics magazine. The circuit has low drift and uses an analog instrument. The input resistance is high.
This simple lie detector was found in Popular Electronics. Transistors are commonly used. The...
This one-transistor alarm can be used with much more sensors than the two shown by the figure....
This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the...