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 medium wave radio with 7 germanium transistors was manufactured in Japan in the 1960s. Its...
In this circuit the frequency is determined by the coil and the variable capacitor. Transistors like the...
This high stability circuit is from the datasheet of the component used which is not very common...