The main feature of this circuit found in an old American publication is that it is powered by the very signal it converts. The transistors are of the time and can be replaced by current types.
This rather sophisticated circuit does not recognize false tones, such as harmonics, and can be...
This circuit is intended for testing circuits with RIAA equalization. We found this configuration in a 1977...
We found this two stage transistor amplifier circuit using RC coupling in a magazine published in...