This toy transistorized organ was found in the May 1970 issue of Radio Electronics magazine. The trimpots are adjusted to the musical notes according to the key.
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...