This old fashioned transistor amplifier was found in a publication of the year 1958. Transformer are the critical components in the circuit and power comes from 6 D cells.
This “zero crossing detector” was found in a manual of operational amplifiers from the 1980s....
With this circuit it is possible to follow the transmission in the range of 2 meters with a...
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...