This circuit was obtained from Popular Electronics of the 1990s. The circuit uses common transistors today and the frequency is given by the crystal.
This charger can be used with one to four AA, AAA, C or D cells. The maximum current is given by R...
This wireless infrared remote sound transmitter is from an article published in the August 1988...
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...