This circuit was obtained from the Encyclopedia of Electronic Circuits volume 5 of 1995. The circuit uses the 4001 CMOS to obtain hysteresis in the sensor feedback.
Found in documentation for radio amateurs of the 70's, this circuit generates signals from 18 to 24...
This receiver was found in a documentation by Gernsback from 1960. The circuit uses high impedance...
This circuit is for transducers (headphones or speakers) of 200 to 300 ohms. The frequency is...