This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer available that timer and the transistors are germanium types. The circuit is intended to receive MW stations.
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...