Vackář oscillator
The Vačkář oscillator is an oscillator whose oscillation frequency is determined by inductance and capacitance. The electronic circuit was developed in 1945 in the company Radioslavia and was in practical use at the Czech Post since 1946. The circuit in 1949 by Jiří Vačkář and 1948 by O. Landini was published (mentioned in the article by Vačkář ).
Interpreted correctly, can be generated with the Vačkář oscillator a very stable frequency oscillation.
Operation
Vačkář the oscillator is an improvement of the Colpitts oscillator. To achieve high frequency stability, the capacitor Ca is connected in parallel to the internal anode-cathode capacitance of the electron tube, is also parallel to the grid-cathode Cg capacity. By these parallel-connected capacitors changes in the supply voltage, the temperature or the load resistance will have less impact on the frequency and on the other oscillators.
The newer design used as shown in the adjacent sketch instead of an electron tube, a junction field effect transistor ( JFET).