This circuit detects changes in magnetic flux in a coil as an external magnetic field moves. The circuit is from Electronics Now magazine, October 1996.
We found this commercial circuit sold as PT-40 in Japan in the 1960s in a documentation of the...
This audio oscillator can also be frequency controlled by an LDR. The circuit is from a 1975...
The circuit shown in the figure is triggered by an input voltage determined by the setting of P1....