Infrared modulated transmitter (CB7247E)

This simple Philips circuit from the 1960s can use any general-purpose transistor. The signal is modulated at 2.7 kHz.

Symmetrical Adjustable Source (CB16785E)
This symmetrical 1.2 to 35 V source was found in a 1994 documentation. The integrated circuits are...
4-channel mixer (CB8756E)
Found in a 90s Elektor, this mixer makes use of integrated circuits of the time. The supply must be...
1 to 5 W amplifier TDA1011 (CB15975E)
This amplifier is specifically designed for portable radio and recorders with a 4 ohms load....