Vackář oscillator

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Vackář oscillator with electron tube
Vackář oscillator with JFET

The Vackář oscillator is an oscillator whose oscillation frequency is determined by inductances and capacitances. The electronic circuit was developed in 1945 by the Radioslavia company and has been in practical use at the Czech Post Office since 1946. The circuit was published in 1949 by Jiří Vackář and in 1948 by O. Landini (mentioned in Vackář's article).

If designed correctly, the Vackář oscillator can generate a very stable frequency oscillation.

functionality

The Vackář oscillator is an improvement on the Colpitts oscillator . In order to achieve high frequency stability, capacitor C a is parallel to the internal anode-cathode capacitance of the electron tube, and C g is also parallel to the grid-cathode capacitance. With these capacitors connected in parallel, changes in supply voltage, temperature or load resistance have less of an effect on the frequency than with other oscillators.

The second (dimensioned) figure uses a junction field effect transistor (JFET) instead of the electron tube; it is an alternate representation of the same circuit.

Footnotes

  1. Jiří Vackář , LC Oscillators and their Frequency Stability , TESLA Report 1949, ch. 4 ( Memento from August 13, 2012 on WebCite )
  2. ^ O. Landini, Radio Rivista, November 1948

Web links