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.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...