Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of 20 times. Phototransistors are types of the time.
Found in a 90s Radio Electronics this circuit requires precision resistors in the dividing...
The advantage of this circuit lies in the fact that it does not need a negative source to generate...
The transistors of this timing circuit may be more modern types such as BC548 and BC558. The...