Found in a 90's EDN this circuit can be used as a shield. The transistor is a general-purpose type and the frequency of the emitted sound is determined by R1 / C1.
This circuit was found in the SGS manual of linear integrated circuits of 1982. The CMRR depends on...
In the figure we have a receiver for frequency modulated light signals (see the transmitter in...
In the figure we have a high stability voltage reference, providing a voltage of 10 V at the...