heterodyne oscillator การใช้

This approach is usually less stable and cannot generate the low frequencies that a heterodyne oscillator can.
Better designs ( e . g ., Moog, Theremax ) may use two pairs of heterodyne oscillators, for both pitch and volume.
The heterodyne oscillator is the ancestor of the " beat frequency oscillator " ( BFO ) which is used to receive radiotelegraphy in communications receivers today.
Modern circuit designs often simplify this circuit and avoid the complexity of two heterodyne oscillators by having a single pitch oscillator, akin to the original theremin's volume circuit.
The advantage of using a VFO as a heterodyning oscillator is that only a small portion of the radio receiver ( the sections before the mixer such as the preamplifier ) need to have a wide bandwidth.