This transistor circuit was found in Mullard's 1960s transistor manual. The transistors are germanium from the time.
This source was found in a 1982 American publication, but can be easily assembled using 2N2995 (PNP...
This receiver can operate with the transmitters shown in previous articles and even others...
We got this circuit in an old 1983 publication, but it can be fitted with equivalent transistors. For Q1...