Oscillator Hartri: Me ke nan? (Tsohon Raka Da Kofin Kirkiro)

Mai shi ne Hartley Oscillator?

Hartley Oscillator (ko da kuma RF oscillator) shine wata na harmonic oscillator. Tashin tafiyar Hartley Oscillator ta gudanar da LC oscillator (yana nufin cikin capacitors da inductors). Hartley oscillators suna tattara don samun harsuna a bandin radiofrequency (saboda haka sunan RF oscillators).

An samu Hartley Oscillators a shekarar 1915 da Ralph Hartley, mahaiki masana'antu na Amurka.

Abubuwan da ke cika ce mai sauƙi a Hartley oscillator shine cewa tunanin cikin ya haɗa da kumbura daya a matsayin capacitor da duk inductor biyu a tsari (ko kuma inductor daya da kungiyar kan), kuma alamun feedback da zan iya buƙatar don tafiyar yana faru daga tsari na inductors biyu.

A cikakken bayanin Hartley Oscillator ta fi sani a cikin Raisu 1:

A nan RC shine resistor na collector kuma resistor RE na emitter yana ƙirƙira network na stabilizing. Kuma resistors R1 da R2 suka ƙirƙira voltage divider bias network don transistor a configuration na common-emitter CE.

Sauɗan, Ci da Co su ne input da output decoupling capacitors kuma CE na emitter yana ƙirƙira bypass capacitor don bypass amplified AC signals. Duk waɗannan components suna ƙunshi abubuwa masu common-emitter amplifier wanda ake bias using voltage divider network.

Amma, Raisu 1 ta fi sani abubuwan da suka ƙunshi L1 da L2, da kuma capacitor C wanda suka ƙirƙira tank circuit (a cikin enclosure na red).

Idan ake faɗinsa power supply, transistor ya faru zuwa conduct, wanda ya ƙara collector current, IC wanda ya charges the capacitor C.

Idan C ta samu muhimman charge, C ya faru zuwa discharge via inductors L1 da L2. Waɗannan cycles na charging da discharging suka ƙara damped oscillations a cikin tank circuit.

Oscillation current a cikin tank circuit ya ƙara AC voltage across inductors L1 da L2 wanda suka ƙara 180o out-of-phase saboda points of contact suka ƙare ground.

Duk da haka, daga figure, ita ce za a iya tabbatar da output na amplifier ya faru across inductor L1 kuma feedback voltage drawn across L2 ya faru zuwa base na transistor.

Saboda haka, za a iya tabbatar da output na amplifier ya ƙare phase da voltage na tank circuit da ya ƙara back energy lost by it while energy fed back to the amplifier circuit will be out-of-phase by 180o.

Feedback voltage wanda ya ƙare 180o out-of-phase with the transistor, an yi additional 180o phase-shift due to the transistor action.

Saboda haka, signal wanda ya faru zuwa output na transistor ya ƙara amplified and will have a net phase-shift of 360o.

A wannan lokacin, idan ake ƙara gain na circuit zuwa ko da feedback ratio given by

(if the coils are wound on the same core with M indicating the mutual inductance)
then the circuit generates the oscillator that can be sustained by maintaining the circuit’s gain to be equal to that of the feedback ratio.

This causes the circuit in Figure 1 to act as an oscillator as it would then satisfy both the conditions of the Barkhausen criteria.

The frequency of such an oscillator is given as

Where,

Hartley oscillators are available in many different configurations including series-or shunt-fed, common-emitter or common-base configured, and BJT (Bipolar Junction Transistor) or FET (Field Effect Transistor) amplifier based.

Further, it is to be noted that the transistor-based amplifier section of Figure 1 can even be replaced by