GB1128481A - Improvements in or relating to frequency dividers - Google Patents

Abstract

1,128,481. Valve oscillating and frequency dividing circuits; pulse circuits. LABORATORNI PRISTROJE NARODNI PODNIK. 11 Jan., 1966 [14 Jan., 1965], No. 1194/66. Headings H3F and H3P. In a frequency dividing arrangement, the first and third grids of a heptode 1 are back-coupled via tuned circuit 15 and crystal 12 to form a stable oscillator, an output at the frequency concerned being available from potentiometer 14. The remaining electrodes are crosscoupled to a triode portion 2 via resistors 21, 22 and capacitor 23 to form a relaxation oscillator synchronized to the frequency of stable oscillations. The rectangular waveform at the anode of triode 2 is differentiated by means of capacitor 24 and fed as synchronizing signal to the grid of a triode 5; the differentiated signal is also rectified by diode 4 to charge capacitor 25 and so develop a positive bias for the grid of triode 5. Triodes 5, 6 are back-coupled via capacitor 52 and common cathode resistor 51 to form a Schmitt trigger circuit, running at the division frequency and providing an output via tuned circuit 61 and potentiometer 62. The arrangement is such that in the absence of the bias derived from synchronizing pulses from the valve 2, the valve 5 is biased so as to be inoperative by the voltage developed across capacitor 54.