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 circuit for analog video signals was found in the August 1970 issue of Radio Electronics...
This 5-range current measurement circuit was found in the September 1989 issue of Radio...
Oscillators up to some megaherts can be made with comparators like the LM139, 239 or 339. Theses...