This is the receiver for the previous circuit, also found in 90s Radio Electronics. The circuit operates at 2.25 MHz, detecting variations in signal frequency due to the Doppler effect.
This application is not modern since few computers have parallel ports. But you can use this...
Using a 741 op-amp this circuit high-pass to 10 kHz was found in the February 1995 issue of...
Found in a 1969 EEE, this circuit is based on an operational amplifier of the time and on old type...