This circuit is from a 1924 book by Gernsback. The receiver uses two tubes and listens to headphones. Power is supplied by battery with the indicated voltages.
This circuit is from an Electronics World of 1967. The described calculations can be applied to...
This well-known configuration was found in a 1982 publication. Other operational amplifiers can be...
This circuit has a gain of 6 dB for low frequencies from 85 Hz and can be used in a mini...