GB655102A - Improvements in electrical oscillation generators - Google Patents

Abstract

655,102. Saw-tooth generating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Oct. 16, 1948, No. 26936. Convention date, Oct. 17, 1947. [Class 40 (vi)] A saw-tooth wave is generated in the anode circuit of a valve by slowly charging a capacitor connected to the grid and rapidly discharging it through a unilateral conductive device con. nected to the secondary of a transformer, the primary of which is connected to an auxiliary electrode of the valve and which applies a voltage developed at the auxiliary electrode to the device to render it conductive. A capacitor 21 which carries a negative charge discharges substantially linearly through resistors 23 and 25 connecting to a +H.T. source with the result that the anode and screen currents rise to produce the long Hank of the saw-tooth wave in the secondary of the anode transformer 7 and a positive diode blocking potential in the secondary 33 of a transformer coupling the screen and control grids. When the valve saturates the blocking potential ceases to be developed and the cathode of diode 27 rapidly becomes negative so that a charging current flows into capacitor 21 to replace its negative charge. The value of the charging current is limited by resistor 23, which also helps to produce the desired shape of the anode current wave. Capacitor 38 and resistor 40 or an equivalent diode or other valve arrangement enables the first part of the long flank to be generated from energy stored in the circuit, and a capacitor 39 increases the natural period of transformer 35 to that of the natural period of oscillation of the deflection circuit. Synchronizing pulses are applied to a tertiary winding 41 of the screen transformer or to the cathode circuit of valve 15. In an alternative circuit (Fig. 2, not shown), the deflection coils are cbnnected in series in the anode circuit of valve 15 or across a portion of an inductor provided in series in the anode circuit. In the former case a damping resistor is connected across the secondary of an additional transformer in the anode circuit. Specification 523,476 is referred to. Reference has been directed by the Comptroller to Specification 628,742.