This mixer with 20 dB gain per channel uses RCA's CA3048 integrated circuits. We found it in the July 1971 Radio Electronics magazine. The power supply does not need to be symmetrical.
This power supply with several transistors can supply a current of several amps and a voltage of...
Found in a 1967 EEE, this circuit oscillates at 20 MHz according to the values of the given...
We found this circuit in a 1974 technical documentation. The circuit can be made with BC549...