Found in a QST magazine from the 90s, this circuit broadcasts on different amateur radio bands depending on the coil. Data for the coil and crystal are provided next to the diagram.
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...