This filter is from the Linear Applications Handbook of the National Semiconductor of 1994. However, it can be used with other operational and modified to operate with other frequencies.
This circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...