B21126E)
This circuit was taken from an old Popular Electronics. The circuit can have its frequency changed from an external signal. The center frequency is given by C1.
This circuit was found in an American documentation and can be added to common amplifiers of any...
This circuit reinforces signals in a frequency range between 1500 and 2000 Hz for use in...
This simple circuit indicates, through an LED, when the water level of a filter (or other kind of...