This selectivity multiplier circuit for 455 kHz IF receivers was found in American documentation from the 1980s. The circuit requires a symmetrical power supply.
Found in an Electronics Now from the 90s, this circuit appears elsewhere in this section and...
This TTL circuit was found in the February 1973 issue of Radio Electronics magazine. The power...
This circuit was found in an old publication about transistor. The original trasistors are...