Электрондық осциллятор: Хартли осцилляторының құрылысы мен қағидалары

Electronic oscillator
The Hartley oscillator is an electronic oscillator circuit in which the oscillation frequency is determined by a tuned circuit consisting of capacitors and inductors, that is, an LC oscillator. The circuit was invented in 1915 by American engineer Ralph Hartley. The distinguishing feature of the Hartley oscillator is that the tuned circuit consists of a single capacitor in parallel with two inductors in series (or a single tapped inductor), and the feedback signal needed for oscillation is taken from the center connection of the two inductors.

The Hartley oscillator was invented by Hartley while he was working for the Research Laboratory of the Western Electric Company. Hartley invented and patented the design in 1915 while overseeing Bell System's transatlantic radiotelephone tests; it was awarded patent number 1,356,763 on October 26, 1920. Note that the basic schematic shown below labeled "Common drain Hartley circuit" is essentially the same as in the patent drawing, except that the tube is replaced by a JFET, and that the battery for a negative grid bias is not needed. In 1946 Hartley was awarded the IRE medal of honor "For his early work on oscillating circuits employing triode tubes and likewise for his early recognition and clear exposition of the fundamental relationship between the total amount of information which may be transmitted over a transmission system of limited band width and the time required. "(The second half of the citation refers to Hartley's work in information theory which largely paralleled Harry Nyquist.)

The schematic shows an example with component values. Instead of field effect transistors, other active components such as bipolar junction transistors or vacuum tubes, capable of producing gain at the desired frequency, could be used. The common drain amplifier has a high input impedance and a low output impedance. Therefore the amplifier input is connected to the high impedance top of the LC circuit C1, L1, L2 and the amplifier output is connected to the low impedance tap of the LC circuit. The grid leak C2 and R1 sets the operating point automatically through grid leak bias. A smaller value of C2 gives less harmonic distortion, but requires a larger load resistor. The load resistor RL is part of the simulation, not part of the circuit.