US2621294A - Circuit for providing timed electrical impulses - Google Patents

Description

Dec. 9, 1952 T- PODBIELNIAK CIRCUIT FOR PROVIDING TIMED ELECTRICAL IMPULSES Filed April 27, 1948 IN V EN TOR.

THADDEUS PODBIELNIAK BY /j 0% ATT ORNEY Patented Dec. 9, 1952 CIRCUIT FOR PROVIDING TIMED ELECTRICAL IMPULSES Thaddeus Podbielniak, Bufialo, N. Y., assignor to the United States of America as represented by the Secretary of the Navy Application April 27, 1948, Serial No. 23,470

2 Claims. (Cl. 250-36) The present invention relates to a process and circuit for providing electrical impulses, which are timed to occur at desired intervals, each impulse moreover being of a desired duration.

An object of the invention is to secure the desired initial timed electrical impulses by means having no movable parts, including a relaxation oscillator and a thermionic tube controlled thereby.

Still more specifically, it is an object of the invention to provide intervals each of the order of one-half second duration, under the control of a relaxation oscillator of twice such period, which, however, itself yields extremely short pulses.

A particular purpose of the invention is to provide a device of this type, that is compact and of relatively small size, to make it suitable for use in a test projectile, to emit, during the travel of the projectile, modulated radio frequency signals, that may be received at a suitable location, and from which the characteristics of projectile performance may be determined. Such devices are commonly called sondes.

While the principles underlying the invention are such that the invention may be utilized in many different circuits, a preferred form is shown by way of example in the accompanying drawing and described in this specification.

The single figure constituting the drawing is the circuit diagram of a timing device intended for a sonde, and embodying the invention.

In said drawing, I3 is a neon glow-lamp or similar gas-filled discharge tube which has a capacitor 12 connected across its terminals, as shown. This constitutes a relaxation oscillator circuit wherein the capacitor may discharge through the neon lamp. In order to charge the capacitor, a resistor ll of suitable value is provided in series relation to the capacitor with respect to the energy source, such as battery [1, through an optional switch 31, to determine the rate of charge.

A thermionic tube 26, shown as a triode, has its cathode 2| connected directly to one terminal of the neon lamp l3 and its grid 20 connected to the other terminal thereof through the capacitor 16. A resistor l9 connects the grid 20 to the negative terminal of the bias voltage source l8. The switch 30 controls the parallel-connected cathode-heating circuits of the tubes 26, 21 and 28, which are connected to the battery 29, through said switch. The switch 3| may be provided, to disconnect the battery I! from the neon lamp circuit, when not in use.

The operation of the circuit above described, certain values of the electrical constants that have been found suitable in practice being-assumed, is as follows:

The capacitor l2 of .09 mfd., with the 10 megohm resistor II in series therewith, will be charged by the source I! of volts in such way that the neon lamp will flash at intervals of approximately 1 second, the exact time being determined by RC, the resistance-capacitance value, in conjunction with the applied voltage and the characteristics of the neon lamp.

As the charge of the capacitor builds up, th voltage at its terminals increases in the well known way. This voltage, in effect, is transmitted through the 1 mid. capacitor l6 and causes the grid 20, connected to the other side thereof, to build up a positive potential, anasmuch as the grid resistor IQ, of 10 megohms, is sufiiciently high to prevent too-rapid readjustment of the grid potential to its normal bias value.

Consequently, when capacitor [2 has charged to about one-half the breakdown voltage of the lamp I3, the grid 20 usually will be sufficiently positive to allow a large anode current to flow in the thermionic tube. This condition of large anodev current continues until the moment the neon lamp fires, when a sudden negative pulse substantially cuts off the anode current by reason of a momentary abnormally high negative bias, followed by the restoration of normal negative potential to the grid.

The winding 22 of a relay is inserted in the anode circuit. This relay may have the tension of its spring 32 preferably so adjusted that the magnetism produced by the anode current will overcome it at such times that the armature 23 thereof is swung from contact 24 to contact 25 and back at equal intervals, remaining on each for approximately -second. This relay may then control any desired mechanical or electrical action in the sonde.

It will be noted that an oscillator, including the thermionic tubes 21 and 28 and the circuits connected thereto, is also provided and has the grid of its tube 28 connected through capacitor [4 of .04 mf., and the radio frequency choke 15, to one side of capacitor l2, which has its other side connected to the cathodes of tubes 2! and 28 as shown. This oscillator is in other respects entirely independent of the circuits previously described, and its purpose is continuously to emit radio frequency radiation, which constitutes the radio signal of the sonde.

However, a potential pulse is applied to the grid of tube 28 each time the glow-lamp I3 fires, and thus a timing signal is impressed on the oscillator output, in synchronism with the operation of the relay 22, and may be received by a properly adjusted-radio receiver, and used toobserveand/ or check'ithe .operationrof the relayifromzaremote point.

While values have been assigned to the electrical magnitudes of certain of the circuit components illustrated, it will be clearthat cthese values are given in a purely suggestive-sensaarid not in any way as limitations. .Moreovenzequivalents may be substituted,forpractically:anygor all the components, for example, the gas inxthe;

glow-lamp [3 may be other than .neon if desired, power supplies of any other preferred type 'may replace the batteries, and so on, withoutcint any manner sacrificing any of the advantages of the ginyention.

H "Therefore, -.-,it:i-should .lbe I understood 2, that the ainventiondsidefinedsolelyinandibyiythe following claims.

,I' claim: 1. .timingsystem :for a periodically. controlled -::lo.ad circuit, comprisingza source misubstantially wcon'stant potentialpza capacitor connected to be charged .irom fiaidi sourcewa seriestcircuit includi-ngziinzseriespcircuitazrelation'an impedance said .-:capacitor';and :said source; of. otential,-*,the:..con- 1 stants of said-seriescircuit controlling the: charging. intervalrz ofwsaid; capacitor, {an 1 grid controlled electric valve: inssaid load circuit :having 38. 0011- trol :grid, a1=source.. otbiasing zpotential connected a-to: said :grid, Lsaid ibiasing potential": tendingrto r-main'tain said valve".noneconduoting-circuit means impressing the potential of saidfcapacitoronsaid zgr-id in opposition to said has potential; said :bias potential and said capacitor :potentiali -=.being so proportioned that a charge. of .the' order of i half charge of said capacitor produces a potential ---sufiicient to overcome-said bias potential torender said- -valve conducting; a cold elect-rode dis- :cha-rge device connected across the terminals of :said-capacitor, saiddischarge device being operative inresponse'to the application :ofiffulr potenti'al ofisaid "capacitor" to' discharge the capacitor ieand render-said:valvenon-conducting.

, ;2.=. In'ean;-old combination oferas resonant':circuit 4 oscillator having a plurality of grid controlled tubes and a relaxation oscillator wherein the latter is used to pulse the former; the improvement, comprising a source of substantially constant potential, a capacitor connected 'to be charged from-said source a seriescircuit includ fiingiin, series icircuit relation anlimpe'dance, said capacitor and said source of potential, the conj stants of said series circuit controlling the charging interval of said capacitor, a grid controlled e'lectric valvehin said load circuit having a con- "itrolled grid, a source of biasing potential con- .mected to .saidzgridisaid biasing potential tending to; maintain said valve non-conducting, circuit meansimpressing-the potential of said capacitor on said grid in opposition to said bias potential,

'said"biaspotential and said capacitor potential being'so'proportioned that a charge of the order of half charge of said capacitor produces a potential sufficient to overcome vsaid bias potential to :render said valve conductin'gya cold-electrode discharge device connected across the-terminals of said capacitor said discharge, device'being operativein'response' 'tOi th'e'application or full potential ofsaid capacitor'todischarge thecapacitor "and render said valve-nonconducting;and a con- 'nectionimpressing thepotential of :saidcapacitor on' the' grid of'at least one of said grid controlled tubes. of said resonant circuit oscillator.

THADDEUS: :PIODBIELNTAK.

R-EEERENCES LCITED lhe qfollowing references-arerof record .inutth-e file of this patent:

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