This General Electric circuit, in a documentation from the 1960s, allows the use of high resistance resistive sensors with unijunction transistors in a relaxation oscillator.
This circuit is of great use today, when solar energy is becoming increasingly important. The...
In figure we have an interesting circuit in which an LED is used as a photoelectric sensor. When...
This circuit is from an old English documentation. It is intended for coupling a microphone to the...