This circuit was found in a 1992 publication. What it does is to light an external lamp when it gets dark. The trigger point adjustment is made in a potentiometer or trimpot and the sensor is a common LDR.
This portable transceiver circuit for the 11 meter or 27 MHz band was found in a 1991...
This circuit was found in an American 1980s documentation. It makes use of an unusual MOSFET today...
This circuit was found in an old Linear Technology documentation. The working principle can be...