US2444998A - Rochelle salt resonator - Google Patents

Rochelle salt resonator Download PDF

Info

Publication number
US2444998A
US2444998A US538142A US53814244A US2444998A US 2444998 A US2444998 A US 2444998A US 538142 A US538142 A US 538142A US 53814244 A US53814244 A US 53814244A US 2444998 A US2444998 A US 2444998A
Authority
US
United States
Prior art keywords
crystal
crystals
frequency
rochelle
direct voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US538142A
Other languages
English (en)
Inventor
Matthias Bernd
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Patelhold Patenverwertungs and Elektro-Holding AG
Original Assignee
Patelhold Patenverwertungs and Elektro-Holding AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Patelhold Patenverwertungs and Elektro-Holding AG filed Critical Patelhold Patenverwertungs and Elektro-Holding AG
Application granted granted Critical
Publication of US2444998A publication Critical patent/US2444998A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/545—Filters comprising resonators of piezoelectric or electrostrictive material including active elements
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/34—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being vacuum tube
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/542—Filters comprising resonators of piezoelectric or electrostrictive material including passive elements

Definitions

  • a Rochelle electric crystal which is caused to oscillate can be regarded as the equivalent of an electrical oscillation circuit, which according to Fig. 1 consists of two capacitances C1 and C2, an inductance L and an ohmic resistance R.
  • This oscillation circuit possesses the disadvantage that the resonance frequency is not sharply defined and the dielectric losses are high.
  • theresonance frequency can be varied by applying a direct voltage to both faces of the crystals. This dependence of the resonance frequency on the applied direct voltage exists over the range within which the polarisation of the crystal shows a hysteresis character as a function of the voltage applied to both faces; that is to say the dependence exists up to field strengths of about 900 v./cm.
  • the present invention thus consists of an oscillation circuit for high frequency electrical oscillations whose frequency is controlled by at least one Rochelle electric crystal, the invention being characterised by the feature that means are provided whereby the operating point is 10- cated in a range within which the polarisation of the Rochelle electric crystal is practically a deflnite function of the voltage applied to both faces of the crystal.
  • Objects of the invention are to improve the selectivity or sharpness of tuning of oscillation circuits which include Rochelle salt crystals, the
  • Objects are to provide oscillation circuits of the type including Rochelle salt crystals which are preloaded or polarized electrically and/or mechanically substantially to eliminate the hysteresis character of the known electrical polarization corresponding to biasing electrical fields of the order of up to about 900 volts per centimeter.
  • Other objects are to provide methods of and apparatus for adjusting the frequency of an oscillation circuit which is frequency stabilized by a Rochelle salt crystal pre-loaded to such a degree that the resonant frequency of the circuit is substantially independent of small changes in polarizing voltages applied to the crystal to pre-load the same.
  • Fig. 1 is the equivalent circuit diagram of a. Rochelle salt crystal
  • Figs. 2 and 3 are circuit diagrams of two oscillation circuits embodying the invention.
  • Figs. 2 and 3 of the accompanying drawing Two constructional examples of the invention are illustrated diagrammatically in Figs. 2 and 3 of the accompanying drawing, Fig. 2 showing a crystal-controlled transmitter and Fig. 3 an electric filter with two Rochelle crystals.
  • the Rochelle electric crystal 1 is separated from the transmitter by the capacitances 2.
  • a suitable direct voltage is applied to both faces. This is supplied to terminals l by a voltage source 5.
  • the direct voltage source is separated from the crystal by the choke coils 3. These prevent high frequency power from escaping over the direct voltage source.
  • the feed back from the anode to the grid circuit occurs over the grid-anode capacitance.
  • the dielectric losses not only depend on the initial voltage but also on the temperature. They .attain a maximum value at the Curie points and have a minimum value between these points.
  • Fig. 3 shows how for example Rochelle electric crystals I are used in a filter arrangement of known type in which each crystal is shunted by a variable condenser 6 and the opposite faces of the crystals are cross-connected by variable condensers I.
  • the direct voltage sources By means of the direct voltage sources the operating point on the Rochelle electric crystals is again located in a range where the losses practically disappear.
  • the direct voltages I are separated from the crystals I by the high frequency blocking elements 3. If necessary the Rochelle electric crystals can also be separated from the rest of the high frequency arrangement.
  • the resonance frequency of the crystals variable for instance so as to make the passing range of a filter variable.
  • the direct voltage should be varied in the hysteresis region, as already mentioned. It has, however, been determined that the resonance frequency also depends on the magnitude of the alternating voltage at the crystal surfaces, so that this voltage can also be employed for varying the frequency.
  • the dielectric losses are high when regulating with direct voltage. Furthermore the necessary alternating voltage alterations are much smaller than the corresponding direct voltage alterations. For this reason it is often an advantage to control the frequency with the alternating voltage.
  • the alteration of the frequency as a function of the alternating voltage amplitude is a maximum when the temperature is so selected that the operating point lies in the region of one of the Curie points, it being particularly advantageous when it is in the region of the upper Curie point.
  • the temperature of the crystal can also be employed for slow changes in frequency, because the frequency follows a temperaturedependent course, whereby there is a minimum value at each Curie point and a maximum value between these points.
  • the direct voltage source for the elimination of the hysteresis losses can be obtained in several ways. Either a special direct voltage source can be provided, or the direct voltage is produced by extracting high frequency energy from the oscillation circuit and if necessary transforming it to a higher voltage and then rectifying it. In order to maintain the direct voltage exactly constant it is advisable to stabilize it.
  • the frequency is to be kept as constant as possible, it is not only necessary to maintain the electrical values but also the temperature constant. Furthermore it is also an advantage to locate the operating point in a range where the resonance frequency changes as little as possible as a function of the temperature. For this purpose the region of maximum frequency between both Curie points is especially favourable. It is, however, also possible to operate with the flattened parts at the Curie points. Furthermore in accordance with the present invention it has been recognized that by applying a field strength exceeding 1400 v./cm it is possible to achieve a considerable flattening of the resonance frequency curve as a function of the temperature, and the curve becomes still flatter if the alternating voltage is less than 0.1 volt.
  • the crystal becomes deformed when the direct voltage is applied. By means of this deformation it is therefore possible to make the hysteresis losses disappear.
  • a favorable constructional form of the invention is therefore obtained when by deforming the Rochelle crystal, for instance by pressure, the operating point is located in a range where the polarisation of the crystal is practically a definite function of the voltage applied to both faces.
  • An electrical high frequency oscillation circult comprising at least one Rochelle salt crystal for controlling the frequency of the circuit, means for impressing an alternating current voltage upon the crystal, and a direct current source for establishing in the crystal an electrical field strength of the order of 1400 volts per centimeter.
  • a filter in combination, a circuit comprising a pair of conductors, a Rochelle electrical crystal in series with each conductor, and means polarizing said crystals to locate the operating points thereof outside the range within which the crystals'exhibit a hysteresis characteristic as a function of the applied polarization, said polarizing means comprising a direct voltage source individual to each crystal and connected to impress a voltage across the opposite faces thereof.

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
US538142A 1943-04-12 1944-05-31 Rochelle salt resonator Expired - Lifetime US2444998A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH587399X 1943-04-12

Publications (1)

Publication Number Publication Date
US2444998A true US2444998A (en) 1948-07-13

Family

ID=4521893

Family Applications (1)

Application Number Title Priority Date Filing Date
US538142A Expired - Lifetime US2444998A (en) 1943-04-12 1944-05-31 Rochelle salt resonator

Country Status (3)

Country Link
US (1) US2444998A (fr)
FR (1) FR903247A (fr)
GB (1) GB587399A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471085A (en) * 1947-06-28 1949-05-24 Sinclair Refining Co Fluid catalyst process for the conversion of hydrocarbons
US2702427A (en) * 1948-03-13 1955-02-22 Roberts Shepard Method of making electromechanically sensitive material
US2878454A (en) * 1953-09-03 1959-03-17 Motorola Inc Piezoelectric crystal filter
US2939089A (en) * 1958-01-06 1960-05-31 Philco Corp Signal generating circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1994220A (en) * 1934-01-03 1935-03-12 Hormel August Metal sheet drying oven
US1996504A (en) * 1933-04-12 1935-04-02 Bell Telephone Labor Inc Wave filter
US2306555A (en) * 1940-05-23 1942-12-29 Research Corp Method for frequency control

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1996504A (en) * 1933-04-12 1935-04-02 Bell Telephone Labor Inc Wave filter
US1994220A (en) * 1934-01-03 1935-03-12 Hormel August Metal sheet drying oven
US2306555A (en) * 1940-05-23 1942-12-29 Research Corp Method for frequency control

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471085A (en) * 1947-06-28 1949-05-24 Sinclair Refining Co Fluid catalyst process for the conversion of hydrocarbons
US2702427A (en) * 1948-03-13 1955-02-22 Roberts Shepard Method of making electromechanically sensitive material
US2878454A (en) * 1953-09-03 1959-03-17 Motorola Inc Piezoelectric crystal filter
US2939089A (en) * 1958-01-06 1960-05-31 Philco Corp Signal generating circuit

Also Published As

Publication number Publication date
FR903247A (fr) 1945-09-27
GB587399A (en) 1947-04-24

Similar Documents

Publication Publication Date Title
US2473556A (en) Device for controlling oscillating circuits
US2306555A (en) Method for frequency control
US3068427A (en) Frequency modulator including voltage sensitive capacitors for changing the effective capacitance and inductance of an oscillator circuit
US2444998A (en) Rochelle salt resonator
DE2539632A1 (de) Kristalloszillator
US2171243A (en) Frequency control system
US1930278A (en) Oscillation generator
US2424246A (en) Frequency-modulated crystal oscillator
US2486265A (en) Variable frequency oscillator
GB615841A (en) Improvements in and relating to piezo-electric resonators
US2130272A (en) Piezoelectric crystal oscillator
US2246179A (en) Electric control circuit
US2043242A (en) High frequency oscillator
US2476804A (en) Control circuit
US1717451A (en) Method of producing oscillations from piezo-electric plates
US2470738A (en) Temperature compensated crystal unit
US1811126A (en) Balanced magnetostrictive oscillator
US2454933A (en) Frequency modulation
US2960666A (en) Transistor oscillator with impedance transformation in feedback circuit
US3477039A (en) Voltage controlled crystal oscillator
US2565842A (en) Frequency stabilizing device for high-frequency oscillators
US2998575A (en) High precision frequency standard comprising silicon or germanium crystal element
US3026488A (en) Frequency modulator having electromechanical oscillator means
US2453243A (en) Frequency modulating and harmonic producer apparatus
US3192485A (en) Tunnel diode frequency controlled oscillator