This circuit uses a power component that is not common today, being recommended by Motorola in the 90's. Note the need for symmetrical power supply.
This simple circuit can be used in a robot that follows the light directly feeding a small motor....
We found this circuit in Radio Electronics magazine from May 1962. The circuit uses rectifier...
We found this circuit in Mullard's 1960s transistor manual. The circuit oscillates at 800 Hz, the...