US2582697A - Blocking oscillator - Google Patents

Description

Jan. 15, 1952 G. HEPP 2,582,697

BLOCKING OSCILLATOR Filed April '7, 1948 GFRA PD H EPP IN VEN TOR.

A GENZ Patented Jan. 15, 1952 BLOCKING OSCILLATOR Gerard Hepp, E-indhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application April 7, 1948, Serial No. 19,455 In the Netherlands April 22, 1947' In known circuit-arrangements for producing impulse-like currents or voltages use is made of a discharge tube, with which is inserted between the anode and grid circuits a back-coupling which is arranged to be such that an anode-current impulse is converted with a given time lag into a grid-voltage impulse, with the result that the anode current of the, tube temporarily passes through the tube in a pulse-like fashion. In such circuit-arrangements the value of the invariably positive current impulses cannot be adjusted to any desired value and is entirely determined by the parameters of the tube, more particularly by those points of the anode-current control-grid voltage characteristic curve of the discharge tube which are widely divergent in straight-line relationship, the term positive impulse being to be understood to mean an impulse at which an anode current passes for a comparatively short time and no anode current passes for a comparatively long time.

The invention has for its object-to provide a circuit-arrangement which permits of also producing negative impulses and which'in addition readily permits of adjusting the impulse to any desired value. In the circuit-arrangement according to the invention, the discharge tube may in addition accomplish other functions, for example, may be used for producing a plurality of positive and/or negative impulses or for amplifying or generating electrical oscillations.

According to the invention, pulse-like currents or voltages are set up in the anode circuit of a discharge tube, a pulse-like voltage taken from the anode circuit charging, through a rectifier, a condenser which becomes discharged, in part, across a resistance and a rectifier with threshold voltage included in the grid circuit of the discharge tube, in such manner that the grid Voltage of the discharge tube varies ina pulse-like fashion if the condenser is discharged below a value corresponding to the said threshold voltage.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing.

Referring to Fig. 1, l designates a discharge tube, the anode circuit of which includes a transformer 2, the secondary winding 3 of which is connected through a rectifier 4 to a condenser 5. Thi condenser 5 is connected through a resistance 6 and a second secondary winding 9 of the transformer 2 to the series combination of a rectifier and a threshold voltage source B1, which combination is included in the r d ci cu t Oi th 5 Claims. (01.250-36) dischargetube I. The pulse-like oscillations may be taken, for example, from a terminal ll;

The operation of the tube is explained with reference to Fig. 2, of which the lower half shows the voltage-variation and the right-hand half shows'the current variation in a ia-Vg anode-current control-grid voltage characteristic curve.

Assuming that at a certain instant a pulse-like voltage is set up in the anode circuit of the-discharge tube I, the secondary 3 of-the transformer 2 included in the anode circuit of the tube I will have induced init a pulse-like voltage which is rectified by a rectifier 4. For the pass direction of the rectifier 4, which directionis indicated in Fig. l, the condenser 5 becomes charged to a positive value; the condenser voltage is denoted by a dotted line at the bottom of Fig. 2. The condenser 5 becomes discharged across-the resistance 6 and the rectifier l with threshold voltage B1- and across the leakage resistance M of the rectifier 4. Since the resistance of the rectifier I is negligible compared with-the resistance 6, the grid I5 of the tube 1 will have a substantially constant potentialB1 a long as the voltage across the condenser 5 exceeds the voltage of the voltage source B3. At the moment when the voltage of condenser 5 falls below the voltage of the voltage source B2, the grid voltage of the tube l (full curve at the bottom of- Fig. 2) drops, with the result that the anode current of this tube also drops (full curve on the right-hand side of Fig. 2). This drop of grid voltage of the tube l is accelerated by the feedback winding 9 of transformer 2, which winding is connected in series with the condenser 5 and the resistance 6, so that it assumes a pulse-like pattern, the level of the impulses produced across the grid of the tube I being determined by the disabling point A of the tube 1.

By providing the rectifier 8 havingv a" threshold voltage B2 it is possible to ensure that the grid voltage cannot drop below the valueBz, so that this permits of controlling the level of the said impulses.

With these circuit-arrangements it becomes manifest that the nonlinear characteristic curve of the discharge tube I need not be utilized, and this permits of using the latter also for the ac complisment of other functions, such as the production of further positive and/or negative impulses or the amplification or production of electrical oscillations. Thus, Fig. 1 shows, for example, a circuit-arrangement in which this tube I also acts as an amplifier of oscillations rendered effective in the grid-circuit of the discharge sired value.

plified voltage and the produced impulses may be taken from the terminal II. In order to prevent the nonpulse-like oscillations produced across,

the anode circuit of the tube I from unduly controlling the grid [5 of the tube I, through the transformer 2 and the winding 9, which, owing to l the conductivity of the rectifier 1 will never be possible as long as the total voltage produced across the resistance 6 exceeds the voltage of the battery B1, provision is made of impedances 'lzand l3 which suppress in the transformer 2 the frequencies of the oscillations fed to the transformer l0.

' 'I 'l'iecircuit-arrangement above described permits of producing negative impulses of any de- Reversal of the pass direction of the rectifiers 4, 1 and 8 and the polarity of the voltage sources B1 and B2 permits of similarly producing positive-impulses.

' What I'claim is:

1 A- circuit arrangement for generating voltagepulses comprising an electron discharge tube having a cathode, a grid and an anode, an anode circuit for applying an operating potential tov said anode,- a charging condenser, first and second rectifiers, means coupled to said anode circuit to derive a voltage pulse therefrom and for applying said pulse through said first rectifier across 'said'condenser to charge same, an impedance coupled to said anode circuit to derive a positive feedback voltage'therefrom, a resistance, a source of direct voltage, means to apply said feedback voltage to said resistance in series with said second rectifier and said source in the order named, a discharge network connected across said condenser and including said resistance, said second rectifier and said source in series relation, and means to apply the voltage developed across said second rectifier between said grid and said cathode, the polarity of said source being arranged inopposition to the polarity of charge on said condenser, said source having a magnitude at which when said charge falls to a predetermined value said tube produces said voltage pulses.

2. An arrangement, as set forth in claim 1, further including a third rectifier connected in series with a second voltage source across said second rectifier, the directivity of said third rectifier being arranged in opposition to that of said second rectifier,

3. An arrangement, as set forth in claim 1, further including a circuit forapplying oscillations to said tube to be amplified, said circuit including means interposed between said grid and said point to apply said oscillations to said tube.

4. A circuit arrangement for producing voltage pulses comprising an electron discharge tube having a cathode, a grid and an anode, a transformer having a primary and first and second secondaries, means to apply a constant potential to said anode through said primary, first and second rectifiers, a charging condenser, said first secondary being connected to said condenser through said first rectifier, a resistance, a source of direct voltage, said second secondary being connected in series with said resistance, said second rectifier and said source in the order named across said condenser, the polarity of said source being opposed to the polarity of the charge attained by said condenser, and means to apply the voltage developed across said second rectifier between said grid and said cathode, said source having a value at which when said condenser is discharged to a predetermined level said tube produces said pulses, said second secondary being connected to provide positive feedback.

5. A circuit arrangement for producing voltage pulses and amplifying oscillations comprising an electron discharge tube having a cathode, a grid and an anode, a transformer having a primary and first and second secondaries, means to apply a constant potential to said anode through said primary, first and second rectifiers, a charging condenser, said first secondary being connected to said condenser through said first rectifier, a resistance, a source of direct voltage, said second secondary being connected in series with said resistance and said second rectifier and said source across said condenser, the polarity of said source being opposed to the polarity of the charge attained by said condenser, said second secondary being arranged to provide positive feedback, means to apply the voltage across said second rectifier between said grid and said cathode, said source having a value at which when said. condenser is discharged to a predetermined level said tube produces said pulses, and transformer means for impressing said oscillations intermediate said grid and said junction of said resistance and said second rectifier.

GERARD HEPP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,207,511 Geiger July 9, 1940 2,250,706 Geiger July 29, 1941

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