Found on an 80's Elektor, this circuit uses common components, being the diode a general purpose germanium. The coils select the frequency range of the indicator that reaches 60 MHz.
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...