We found this circuit in the Texas Instruments optoelectronics manual. Field effect transistors can be BF245 and bipolar BC548. The sensor is a photodiode in the photo-generator mode.
This well-designed sinusoidal oscillator by Wien bridge was found in ancient European...
This is a circuit for testing small lamps and LEDs. The lamps that can be tested are the ones...
Found in a Popular Electronics from the 90's, this circuit can be implemented with almost any...