This audio level indication system for microphones was found in Radio Electronics from the 90s. The components used are common today.
This circuit found in a 1964 US publication reverses the signal level by providing 9 to 0 V...
This charger can be used with one to four AA, AAA, C or D cells. The maximum current is given by R...
This ultra-low consumption circuit was originally designed to be powered by a solar panel or small...