We found this circuit in a 1973 publication. The circuit lets frequencies below 480 kHz pass through with an output impedance of 1k. The circuit can be implemented with current operational.
We found this circuit in a 1973 documentation. The null adjustment trimpot is 10k. The circuit can be...
This circuit is from Radio Electronics from April 1977. The circuit is for analog lines using...
The indicator for this circuit is a mini buzzer with a 1.5 V oscillator. The circuit can also be...