This receiver of two transistors for the 3.5 MHz band was found in a circuit manual from the 80's. The coil data are found next to the diagram and the transistors can be general purpose PNP.
Using bipolar, FETs and unijunction this long-lasting timer can reach 10 hours with good quality...
The configuration shown is from the National Semiconductor Linear Applications Handbook. The...
This shield circuit uses a common CMOS port. The voltage depends on the interfaced logic. The...