This circuit was found in a 1980s documentation for amateur radio. The circuit is for 9 MHz signals and values in parentheses for FI of 455 kHz. The circuit can be adapted to other frequencies.
We found this configuration in an early 1977 publication. The PNP transistor may be the BC558 and...
This circuit is indicated to operation with piezoeletric transdicers or other with high impedance...
This circuit was found in a 90s Radio Electronics. The load is an LED, but the circuit can be...