Hello guys I would appreciate some help from your side. I need to implement an audio circuit that doubles the incoming signal frequency, that is f(t) => f(2*t) for any frequency and any kind of signal, not just a fixed one for that I could use a tuned class C amplifier.
I am interested also in the theory beyound this circuit. I would applreciate also some e-books on the analog circuit design and audio Fx.
Thank in advance...
If you use an analog multiplier and feed your signal into both inputs you will get a double frequency output and a DC output. Capacitor coupling will eliminate the DC. These chips go by MPY pefixes. The old Burr Brown now bought by TI has some. Here is one **broken link removed**
If you want a cheaper form, use a full wave rectifier. Put the signal through both an inverting gain and a noninverting gain amplifiers. Put diodes from these outputs to the inputs of an inverting stage with two resistor inputs. this will get you mostly second harmonic output.