On: Practical Radio Circuits (2003) [pdf]

[rjsw]

I worked through this [1] book (PDF) as a child, everything worked fine but have no idea if component availability has changed.

[1] https://www.worldradiohistory.com/BOOKSHELF-ARH/Technology/M...

[drivers99 → rjsw]

Nice, I ran across that a month or two ago and it was great. I got to the OC71 germanium transistor and found out they're obsolete.

[kazinator → drivers99]

Silicon PNP transistors should work in those circuits.

It's also trivial to reverse all the polarities in the circuits and switch to NPN. Use a positive supply voltage rather than negative, flip the rectifier diode around as well as all the electrolytic caps.

[kazinator → kazinator]

In that most advanced circuit where are two diode drops against the BE junction of the transistor, you almost certainly want silicon diodes to go with the silicon transistor. The diode type is not otherwise critical. Other than that, I don't see any transistor biasing that depends on a detailed model of the germanium transistor.