US1738041A - Piezo-electric crystal oscillator - Google Patents

Description

Dec. 3, .1929. A. cnos sL Y M C 1.3733941 PIEZO ELECTRIC CRYSTAL OSCILLATOR Filed May 28. 1926 INVENTOR. 22%! fives/9 f z d ATTORNEY l atente l lac; was

oi: the oh'jects or my invention is to de cuit arrangement tor pie-no crystal controlled electron e os hy "which the high potential direct ply system. may be segmented cui which high :trequency os- "oduccd for porn .tti the he oscillat, Cll'ffiillll rude high potential supply eye my invention to pro lit for a pieao clc to tune oscillato J. ohyect M rem i at m er system. Without resort ne oil stopping condensers id or choke coil invention been illustrated in detail .i accompanying drawings which will be understood more clearly "from the specifica tion hereinafterfollowing. Iln the drawings lligure l. diagrammaticah ly illustrates m invention and llig. 2 shows a modified on"- cuit arrangement wherein the piezo electric control element is in slightly diiierent ar rangement with respect to the electrodes of the electron tube system.

ln controlling an electron tube system'by a piezo electric crystal element l have round that special provision must be made in .the electron tube oscillator circuits for securing high etliciency in the generation of high irean quency oscillations. For the proper functioning ot a piezo electric frequency control system a relatively high potential issupplied to the plate circuit of the electron tube system.

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It is not unusual to employ 1,000 volts on the as plate circuit of an electron tube having a rating of approximately 150 Watts. Thehigh frequency oscillations correspondlng to the frequency of the piezo electric crystal whlch is associated with the electron tube system 60 are by my circuit arrangement made to occur the circuit arrangement cit contact plates l till? fllllfdlllltlllhlltlilili'lhl', L ltirlll'ldilifi'll tilllllffl'lllllllhh, iiiliihlillllillillllit llilill i filllltlt illitdi'l llltllld' tilt ilcrial l lo ill'tllhlt.

in a circuit independent oi the output circuit of the electron tube system, ll provide pan -llel iced system irons the pieao electric con-- trolled electron tube system to the high trequency oscillation circuit, 'lihe oscillation circuit is not connected series Wllilfli the out put circuit of the electron tube system been customary heretofore in the art but is connected in parallel With the electron tube system entirely independent of the high potential supply Parts of the high irec uency oscillation. circuit are maintained ground potential and in this "Way adjustment may be made ircrn time to time Without subjecting the operator to injury trom the high poten tials Which are present The separ te high frequency oscillation circuit facilitates the coupling of the Lirequency control system and oscillator to a povver amplification system A direct connection may he made from. points along the inductance oi the high frequency oscillation circuit to the grid circuit of the power amplification system tor thus obtaining the required controlling voltage Without resort to the use ed stoppingcondensers and their associated grid lealr or cholre coil sys tems,

lteiferring to the drawings in more detail reference character 1 designates the pieao electric crystal which is positioned between and l which connected across the grid and filament electrodes of the electron tube in In order to place the proper potential uponthe piezo electric crystal element 1 1 provide a highfrecyuency choke coil 2 and a battery 3 for normally biasing the piezo electric crystal circuit tor permitting the crystal to operate at substantially no load, as has been described more fully in my copending application, Serial Number 26,968, filed April 30, 1925, now Patent 1,696,626 of December 25, 1928. The output circuit of the electron tube 4 includes the plate and filament electrodes connected in series with a .high potential source 6 through high frequency choke coil 5. A condenser 7 is provided for by-passingthe high frequency cur rent from the high voltage direct current circuit. Radio frequency by-pass condenser llili 8 rovides radio circuit which consists of an in W takes justment.

. ductive a path over which the generated frequency currents are transferred to an independent high frequenqy oscillation uctance 9, a variable condenser 10 and an ammeter 11. The. frequency controlsystem is rounded as represented at 12, and it will be 0 served that one terminal of the inductance 9 and one side of the condenser 10 are at round poten* tial and in such condition can fie safely handled by an o erator during the process of adhis condition, particularly with respect to the'movable lates of the variable condenser 10 is ideal or the manipulation of the tuning feature of the circuit without injury to the operator. In systems hereto fore employed where the high frequency oscillation circuit is series connected in the output circuit substantial insulation has been necessa for the parts of the oscillation system an extreme precaution has been required in the adjustment of the circuits for avoiding severe shock due to the fact that when touching either the inductance or the condenser another path to ound is rovided through the operators dy by w ich the high voltage dlrect current W111 flow. my arrangement the tuned circuit is so situated that only high frequency current flows in that circuit and one terminal of either the inductance or the condenser can be touched by the operator during the process ofltuning without any disastrous effect.

By" virtue of the absence of high voltage direct current in the tuned circuit 10 and 11, a direct connection to the grid circuit of the power amplifying system me. be readily made and the required contro g voltage is thus obtained without the introduction of condensers, associated grid leaks or c e coil systems.

As represented in Fig. 2 the piezo electric crystal element may be positioned between the plate an $31 electrodes of the electron tube 4. By arrangement a change in the .reactance nature of the tuned circuit lace. In Fig. 1 the tuned circuit 9, 11 is so tuned that it affords-an inreactance for the frequency towhich the circuit is oscillating. In Fig. 2 the tuning should be such that the tuned circuit affords a capacitive reactance for the "freuency at which the circuit is oscillating. ahis condition is brought about by the location of the piezo electric substance in the circuits and theresultant change in phase re- 'lationships of the two circuits to produce a condition of oscillation.

e numerous advantages arising out of the parallel feed system constructed in accordance with my invention will be readily understood from the description herein.

While I have described my invention in preferred embodiments, I desire it quency oscillation circuit whereby to be understood that modifications in detail may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a frequency control system an electron tube having grid, filament and plate electrodes, input and output circuit interconnecting sald electrodes, a high potential supply system connected in series with said output clrcuit, a radio frequency choke coil in series therewith, a piezo electric crystal element connected in series in said input circuit, to control the operation of said circuits, an independent radio frequency choke coil connected in said input circuit a high frequency oscillation circuit and connections from said output circuit to said high frequency oscillation circuit whereby high frequency oscillations corresponding to the natural frequency of said plezo electric c s- .tal element are sustained in said high quenc oscillation circuit.

2. Iii a frequency control system an electron tube having grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, a hi h potential source interposed in series in sai cuit and having means comprisin a radio frequency choke coil for excluding igh frequency oscillations therefrom, a piezo electric crystal element arranged in said input circuit, an independent radio frequency choke coil disposed in said in ut circuit means in said in ut circuit for fixing the potential of one si e of said piezo electric crystal element, a high frequency oscillation circuit and parallel connections between ints in said output circuit with said hig frehigh frequency oscillations at the natural fr equency of said piezo electric crystal element may be sustained in said high frequency oscillation circuit independent of said high source.

3. In a frequency control system an electron tube having grid, filament and plate electrodes, input and output circuits interconnecting said electrodes, a hi h potential source interposed in series in sai output circuit and having means comprising a radio frequency choke coil connected between said plate electrode and said source for excludmg high frequency oscillations therefrom, a peao electric crystal element connected in sa1 cuit fpr fixing the potential of one side of said piezo electric crystal element, a radio frequency choke coil disposed between said means and the grid electrode of said electron tube a high frequency oscillation circuit, said circuit including inductance and capacity with one side of said inductance and capacity potential output cir-.

input circuit, means in said input cir- A no at ground potential and parallel connections I between sald high frequency oscillation circuit and said output oircult whereby hi h frequenc oscillatlons corresponding to t 0 natural requency of gaid piezo electric o s-- tal element are sustalned by said high equency oscillation circuit.-

. ALFRED OROSSLEY.

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