This circuit was found in a 1967 Electronics World. We can design it with a BF245 for the FET and a BC558 for the bipolar transistor. The circuit has 3 scales and a 10 M ohm input resistance.
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...