These circuits were found in Exar documentation from the 90s. The circuits use both a small speaker and a piezoelectric transducer. The integrated circuit is not common today.
The integrated circuit 4136 consists of operational amplifiers of type 741 in the same enclosure and...
In the figure we have an active high pass filter of 100 Hz, suggested by National Semiconductor in its 1994...
According to the consulted American publication of the 1980s, a zener diode can be used for DC...