Found in the June 1987 issue of Radio Electronics magazine, this circuit uses well-known CMOS components. The circuit has a CMOS amplifier stage that drives a small speaker.
The filter shown in the figure, using only an operational amplifier, is characterized by allowing 1...
Found in a 90s American documentation, this circuit can be used as a shield, just change the...
Found in a Philips' 1968 documentation, this circuit is slightly different from the previous one. The...