CN206698417U - A kind of servo circuit of superaudio sine wave electronic pipe amplifier filament - Google Patents

Abstract

The utility model discloses a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament, it includes sine wave signal and circuit, digital regulation resistance, low pass filter, power amplification circuit, cpu circuit and power circuit occurs, sine wave signal caused by circuit occurs for sine wave signal by filtering out higher hamonic wave into low pass filter after digital regulation resistance partial pressure, the sine wave ingoing power amplifying circuit for obtaining 25KHz amplitude stabilization carries out power amplification, and the sine wave for producing 6.3VRMS, 25KHz provides driving voltage for discharge-tube amplifier filament；Cpu circuit is used to control sine wave signal generation circuit generation sine wave signal to provide stable excitation power supply for discharge-tube amplifier filament and controls the voltage of discharge-tube amplifier filament slowly to rise by digital regulation resistance；Power circuit for servo circuit providing working power.The utility model, which can not only remove 50Hz Hz noises, improves tonequality, and improves the life-span of filament.

Description

A kind of servo circuit of superaudio sine wave electronic pipe amplifier filament

Technical field

A kind of servo circuit of superaudio sine wave electronic pipe amplifier filament is the utility model is related to, belongs to electron tube and puts Big device filament drive technical field.

Background technology

Discharge-tube amplifier is also known as courage machine, is that sound equipment industry is most ancient and unfailing tree green for a long time, it is significant excellent Point is that sound is sweet soft, it is warm it is resistance to listen, music sense is good, and especially dynamic range is big, and linear is good, absolutely not other device institute energy Substitute, top stereo set is the courage machine using discharge-tube amplifier Technology design without exception in the world today.Therefore Courage machine is furtherd investigate, and the digitizing technique new technology for combining current new theory sum carries out upgrading to traditional courage machine and changed Enter, improving performance, be significantly to work.

Traditional electronics pipe power supply circuit typically by the electric power generating composition of the filament of supply electron tube, anode and grid, is also known as " first electricity ", " second electricity ", " the third electricity ".Wherein " second electricity ", " the third electricity ", are become by the secondary high pressure of power transformer after complete be rectified The DC voltage of pulsation, then the LC filter circuits formed by capacitor and inductor, obtain smooth DC voltage supply, 50Hz power frequencies Interference is filtered out in power unit by capacitor and inductor, is not entered inside electron tube.But " first electricity " therein is also known as filament voltage one As directly fed by alternating voltage, 50Hz power frequencies are directly entered electron tube and are internally formed an industrial frequency interference source, use conventional method It is not easy to eliminate.

At present, conventional filament power supply circuit mainly has two kinds of forms of frequency Alternating Current Power Supply and direct current supply.But they are deposited Respective the problem of, there is necessity of Promotion Transformation, concrete analysis is as follows

First, industrial frequency AC power supply circuit

Industrial frequency AC power supply is most common filament power supply mode.6.3V caused by the Filament Winding of power transformer is exchanged Voltage is directly powered to filament.But this power supply mode top grade amplifier no longer uses.

Current high-grade discharge-tube amplifier suppresses alternating current impression noise, all using exchange filament to reduce filament interference Earthed circuit.Exchange filament earthed circuit mainly has transformer center tap and the balance of potentiometer to be grounded two kinds of forms.1) become The centre tapped mode of depressor：Centre cap is set in power transformer Filament Winding and is grounded centre cap, filament line It is attached using twisted-pair feeder, using two groups of Filament Winding senses of current on the contrary, making electric field cancel out each other, to suppress alternating current impression Noise.2) the balance earthing mode of potentiometer：

Wheatstone bridge is formed using two additional resistances and filament resistance, during electric bridge approximate equilibrium, center voltage balance, The sense of current is on the contrary, make electric field cancel out each other, to suppress alternating current impression noise.Or using potentiometer, it is flat to accurate adjustment Weighing apparatus, this circuit are used in the transformer circuit of non-stop layer tap.

220V power frequency civil powers are a unstable power supplys.In city Electrical change it is positive and negative 10 when, 6.3V filament voltage becomes Change between 6.93 to 5.67.Sound quality deterioration when voltage is low, sound " feeling is aroused " when voltage is high, voltage is found in actual tests Fluctuation, influence of the influence far smaller than to filament to screen level.It is the driving source that electronics occurs in view of filament in electron tube, protects The stabilization for holding driving source is necessary, therefore imperative to AC filament voltages progress voltage stabilizing, is usually using external at present The method of high-power voltage stabilizer is realized.

2nd, DC power-supply circuit

In order to thoroughly remove 50Hz AC influences, and stability of power supply is improved, some discharge-tube amplifiers employ direct current Power supply circuit.DC power-supply circuit uses RC filtering or conventional voltage-stabilized power supply circuit to provide a stable direct current for filament and supplied Although circuit, direct current supply have blocked 50Hz exchanges into the approach of electron tube, it appears that eliminate filament from " theory " and deposit AC influence, but by actual audition and analyse in depth after find its negative effect and it is huge, it might even be possible to says directly Stream power supply plan loses more than gain.

Problems be present in the DC power-supply circuit of filament：

1st, direct current can produce the magnetic field of a polarity fixation by filament, and the transmitting to electronics is (especially to the pole of directly-heated three Pipe) deflecting effect is produced, trajectory of electron motion is reduced into curve, the electron amount of relative unit time transmitting；Also drop The low kinetic energy of electron emission, weaken its dynamics.

2nd, filament magnetizes, and is one of physical cause for causing direct current burn-out life shorter.Transmitting of the alternating current to electronics Influence is not deflected.The movement locus of electronics is most short air line distance, and the kinetic energy foot of electronics, emission rate is fast, the unit interval The electron amount of transmitting is more.Here it is the exchange filament courage machine music dynamics physics stronger than direct current filament courage machine music dynamics is former Cause.

3rd, the power supply of direct current filament can cause the early ageing of electron tube.Electrochemistry Knowledge shows：The chemical electrode of different metals Gesture is each different, and D.C. high-current causes electric corruption by that can produce electrochemical effect during the junctions of two kinds of different metal materials Erosion.The heater current of power tube is quite big, is changed to after direct current supply that filament and the weld of pin leads may be because of direct currents Galvano-cautery and blow, the life-span for reducing electron tube makes electron tube premature breakdown.

Actual audition also demonstrates that filament Alternating Current Power Supply is more preferable than direct current supply tone color, and burn-out life is longer.So direct current lamp Silk power supply is not a good power supply plan.

Above two tradition power supply plan can not perfectly solve the problems, such as the interference problem and burn-out life of filament power supply, add Filament bear big dash current when upper electric, easily cause filament impact fusing, influence the life of tube.Based on more than Analysis, the utility model proposes a kind of superaudio discharge-tube amplifier filament servo circuit.

Utility model content

For above-mentioned deficiency, the utility model provides a kind of servo electricity of superaudio sine wave electronic pipe amplifier filament Road, it, which can not only remove 50Hz Hz noises, improves tonequality, and can improve the life-span of filament.

The technical scheme in the invention for solving the technical problem is：A kind of superaudio sine wave electronic pipe amplifier The servo circuit of filament, it is characterized in that, including sine wave signal generation circuit, digital regulation resistance, low pass filter, power amplification Circuit, cpu circuit and power circuit, described sine wave signal occur circuit, digital regulation resistance, low pass filter, power and put Big circuit is sequentially connected, and sine wave signal caused by circuit occurs for sine wave signal by entering low pass after digital regulation resistance partial pressure Wave filter filters out higher hamonic wave, and the sine wave ingoing power amplifying circuit for obtaining 25KHz amplitude stabilization carries out power amplification, production Raw 6.3VRMS, 25KHz sine wave provide driving voltage for discharge-tube amplifier filament；The cpu circuit respectively with sine wave Signal generating circuit connects with digital regulation resistance, is electron tube for controlling sine wave signal that circuit occurs to produce sine wave signal Amplifier filament provides stable excitation power supply and controls the voltage of discharge-tube amplifier filament slowly to rise by digital regulation resistance； The power circuit for servo circuit providing working power.

Preferably, the sine wave signal occur circuit include 25M crystal oscillators, DDS chips AD9833, polarized electric capacity E10, Polarity free capacitor C10, polarity free capacitor C11, polarity free capacitor C12, the digital regulation resistance use AD5263 digital regulation resistances, The low pass filter includes polarity free capacitor C13, polarity free capacitor C14, polarity free capacitor C15, polarity free capacitor C16, electricity Hinder R10, resistance R11 and AD829 operational amplifier, the power amplification circuit include resistance R12, resistance R13, resistance R14 and LM3886 chips；

The VCC pin and H pins of the 25M crystal oscillators connect 3.3V voltages, GND pin ground connection, OUT pins and DDS cores respectively Piece AD9833 pin 5 is connected；The pin 1 of the DDS chips AD9833 is connected by polarity free capacitor C11 with pin 1 to be followed by 3.3V voltages, pin 1 are also grounded after polarity free capacitor C10, and pin 3 is grounded after polarized electric capacity E10, the He of pin 4 Pin 9 is grounded after being connected respectively with the B ends of AD5263 digital regulation resistances, and pin 10 is connected with the A ends of digital regulation resistance；The nothing Polar capacitor C12 is connected in parallel between the side a and b of AD5263 digital regulation resistances；The W ends of the AD5263 digital regulation resistances are successively It is connected after polarity free capacitor C13, resistance R10, resistance R11 with the normal phase input end of AD829 operational amplifiers, AD829 fortune Calculate amplifier normal phase input end be also grounded after polarity free capacitor C15, the inverting input of AD829 operational amplifiers with it is defeated Go out after end is connected and be connected to after polarity free capacitor C14 between resistance R10 and resistance R11, the positive electricity of AD829 operational amplifiers Source and negative power end connect positive 12V voltages and negative 12V voltages respectively, and the output end of AD829 operational amplifiers passes through nonpolarity electricity Holding C16 with the normal phase input end of LM3886 chips to be connected, the normal phase input end of LM3886 chips is also grounded after resistance R12, The inverting input of LM3886 chips is connected by resistance R13 with the output end of LM3886 chips and inverting input is also by electricity It is grounded after resistance R14, the positive power source terminal and negative power end of LM3886 chips connect positive 12V voltages and negative 12V voltages, LM3886 cores respectively The earth terminal ground connection of piece, the output end of LM3886 chips are connected with J1 joints.

Preferably, the J1 joints are connected using twisted-pair feeder with discharge-tube amplifier filament.

Preferably, the cpu circuit includes STM32 chips and its peripheral circuits, pin 9, the pin of the STM32 chips 11 and pin 13 be connected respectively with DDS chips AD9833 pin 8, pin 7 and pin 6, the pin 10 and pin of STM32 chips 12 are connected with the pin 13 and pin 16 of AD5263 digital regulation resistances respectively, the pin 11 of the AD5263 digital regulation resistances and draw Pin 12 is connected with DDS chips AD9833 pin 6 and pin 7 respectively.

Preferably, the power circuit includes transformer T1, rectifier bridge BG1, polarity free capacitor C20, polarity free capacitor C21, polarity free capacitor C22, polarity free capacitor C23, π type LC wave filters, polarity free capacitor C4, polarity free capacitor C5 and LT1117 Voltage-stablizer, the π types LC wave filters include polar capacitor E20, polarized electric capacity E21, polarized electric capacity E22, polarized electricity Hold E23, inductance L1 and inductance L2, the transformer T1 primary side access 220V electric mains, transformer T1 secondary side with Rectifier bridge BG1 input is connected, rectifier bridge BG1 positive output end one end with polarity free capacitor C20, polarized electric capacity respectively E20 one end is connected with inductance L1 one end, the other end of inductance L1 one end with polarized electric capacity E21, electrodeless respectively Property electric capacity C21 one end is connected with positive 12V voltage output ends, and rectifier bridge BG1 negative output terminal is respectively with polarity free capacitor C22's One end, polarized electric capacity E22 one end are connected with inductance L2 one end, the other end of the inductance L2 respectively with polarized electric capacity E23 one end, polarity free capacitor C23 one end are connected with negative 12V voltage output ends, the polarity free capacitor C20 other end, have pole The property electric capacity E20 other end, the polarized electric capacity E21 other end, the polarity free capacitor C21 other end, polarity free capacitor C22 The other end, the polarized electric capacity E22 other end, the polarized electric capacity E23 other end are connected with the polarity free capacitor C23 other end After be grounded；The voltage input end of LT1117 voltage-stablizers one end with positive 12V voltage output ends and polarity free capacitor C4 respectively It is connected, the earth terminals of LT1117 voltage-stablizers is after the other end with polarity free capacitor C4, polarity free capacitor C5 one end are connected respectively Ground connection, the voltage output end of LT1117 voltage-stablizers are connected with polarity free capacitor the C5 other end and 3.3V voltage output ends respectively.

Preferably, the secondary side neutral ground of the power transformer T1.

The beneficial effects of the utility model are：

The utility model has abandoned traditional electron tube heater power supply plan, substitutes with superaudio filament power supply mode, this It is the Beneficial for carrying out performance boost to conditional electronic pipe amplifier using modern digital technology.

The utility model discharge-tube amplifier provides the driving voltage of silent-sound pure sine wave for filament, so drives The a-c cycle of discharge-tube amplifier heater current is beyond the sense of hearing (20H-20KHz) of human ear, and human ear can not perceive, because being Pure sine wave Alternating Current Power Supply, so Traditional DC has not existed the drawbacks of power supply.Consideration is because according to number with pure sine wave Word signal processing theory, pure sine wave do not have harmonic wave interference；The sine wave radiation interference of slightly above audio is not also serious.Exchange supplies Electricity will not have undesirable effect to filament.In order to avoid it is upper electric when whole rated voltage moment be applied directly to filament filament rushed Hit, the utility model devises soft electrification circuit and (realizes the soft of discharge-tube amplifier filament using cpu circuit and digital regulation resistance Upper electricity), realized with digital regulation resistance, the digital regulation resistance zero setting when upper electric, the tune of linear smoothing in ten seconds after the power-up To maximum, realize that filament voltage by zero to rated value " soft upper electricity ", protects filament from impacting, improves the longevity of filament Life, enables the life-span of electron tube to extend.

Sine wave signal caused by the utility model DDS chips, by being irrigated after digital regulation resistance partial pressure into second order Bart This low pass filter filters out higher hamonic wave, obtains the sine wave of 25KHz amplitude stabilization, the amplification formed afterwards into LM3886 Device carries out power amplification, produces 6.3VRMS, and 25KHz sine wave provides driving voltage for electron tube heater.

Sine-wave generator is made up of U1 (AD9833) and peripheral components, is connected by SPI mouths with CPU, CPU, which passes through, to be configured The sine wave that register inside U1 produces 25KHz is exported by 10 pin, access digital regulation resistance U2 A pin, in the control of program Lower to produce an amplitude by 0 to 0.6Vp-p sine wave, digital regulation resistance is when upper electric by zero to maximum slowly varying generation The soft power up that one filament slowly powers up.To protect filament from heavy current impact, extend the life of tube.U2 output pins The second order Butterworth LPF that the cut-off frequency of W access R10-11, C14-15, U3 compositions is 40KHz, the Q of wave filter It is worth for 0.707, multiplication factor 1, exports through C16, power amplification is carried out into U4 (LM3886), in order to improve effect in circuit Rate, not using mu balanced circuit, it is contemplated that inherently a kind of power amplifiers of LM3886, there is very high PSRR (PSRR Representative value is 120dB), it can be approximately considered, the stable then output signal of input signal is also stable, so completes friendship indirectly Flow the filament AC voltage-stabilizing under electric power thus supplied.Power amplifier is the in-phase amplifier connection of standard, and multiplication factor is determined by R13, R14, Multiplication factor calculation formula is G=(1+R13/R14), changes R13, R14 ratio and can change output voltage, output voltage by Input voltage and multiplication factor G are determined, unrelated with mains fluctuations, because input voltage is by reference power supply and D/ in U1 piece A converters export, and itself is highly stable, and equivalent to AC voltage-stabilizing is completed, filament supply is exported by J1, and filament line is using double Twisted wire is attached, and using two groups of Filament Winding senses of current on the contrary, being grounded with reference to power transformer, electric field is cancelled out each other, Ultrasonic alternating current impression noise can effectively be suppressed.

The utility model filament power supply circuit for analyzing discharge-tube amplifier deep in detail, and combine current numeral Change technology proposes the superaudio sine wave electronic pipe amplifier filament servo circuit based on Direct Digital, for electricity The filament power supply of sub- pipe amplifier, extends the life-span of filament, eliminates hum, improve the tonequality of discharge-tube amplifier.

The utility model proposes a kind of " superaudio discharge-tube amplifier filament servo circuit ", coordinates soft upper electricity of starting shooting, While removing 50Hz Hz noises improves tonequality, the life-span of filament is also improved.

Brief description of the drawings

Fig. 1 is circuit theory diagrams of the present utility model；

Fig. 2 is that circuit, digital regulation resistance, low pass filter and power amplification occur for sine wave signal described in the utility model The circuit diagram of circuit；

Fig. 3 is the circuit diagram of digital regulation resistance described in the utility model；

Fig. 4 is the circuit diagram of cpu circuit described in the utility model；

Fig. 5 is the circuit diagram of power circuit described in the utility model.

Embodiment

For the technical characterstic for illustrating this programme can be understood, below by embodiment and its accompanying drawing is combined to this practicality It is new to be described in detail.Following disclosure provide many different embodiments or example be used for realizing it is of the present utility model not Same structure.In order to simplify disclosure of the present utility model, hereinafter the part and setting of specific examples are described.In addition, this Utility model can in different examples repeat reference numerals and/or letter.This repetition be for purposes of simplicity and clarity, Relation between itself not indicating discussed various embodiments and/or setting.It should be noted that part illustrated in the accompanying drawings It is not drawn necessarily to scale.It is unnecessary to avoid that the utility model eliminates the description to known assemblies and treatment technology and process Ground limits the utility model.

As shown in Figures 1 to 5, the servo electricity of a kind of superaudio sine wave electronic pipe amplifier filament of the present utility model Road, it includes sine wave signal and circuit, digital regulation resistance, low pass filter, power amplification circuit, cpu circuit and power supply occurs Circuit, described sine wave signal occurs circuit, digital regulation resistance, low pass filter, power amplification circuit and is sequentially connected, sinusoidal Sine wave signal caused by ripple signal generating circuit by filtering out higher hamonic wave into low pass filter after digital regulation resistance partial pressure, The sine wave ingoing power amplifying circuit for obtaining 25KHz amplitude stabilization carries out power amplification, is producing 6.3VRMS, 25KHz just String ripple provides driving voltage for discharge-tube amplifier filament；With sine wave signal circuit and numeral occur for the cpu circuit respectively Potentiometer is connected, and stabilization is provided for discharge-tube amplifier filament for controlling sine wave signal that circuit generation sine wave signal occurs Excitation power supply and by digital regulation resistance control discharge-tube amplifier filament voltage slowly rise；The power circuit to for Servo circuit provides working power.

Preferably, as shown in Fig. 2 sine wave signal generation circuit includes 25M crystal oscillators, DDS chips AD9833, has pole Property electric capacity E10, polarity free capacitor C10, polarity free capacitor C11, polarity free capacitor C12, the digital regulation resistance use AD5263 Digital regulation resistance, the low pass filter include polarity free capacitor C13, polarity free capacitor C14, polarity free capacitor C15, nonpolarity Electric capacity C16, resistance R10, resistance R11 and AD829 operational amplifier, the power amplification circuit include resistance R12, resistance R13, Resistance R14 and LM3886 chip.The VCC pin and H pins of the 25M crystal oscillators meet 3.3V voltages, GND pin ground connection, OUT respectively Pin is connected with DDS chips AD9833 pin 5；The pin 1 of the DDS chips AD9833 is by polarity free capacitor C11 with drawing Pin 1, which is connected, is followed by 3.3V voltages, and pin 1 is also grounded after polarity free capacitor C10, and pin 3 is followed by by polarized electric capacity E10 Ground, pin 4 and pin 9 are grounded after being connected respectively with the B ends of AD5263 digital regulation resistances, the A ends of pin 10 and digital regulation resistance It is connected；The polarity free capacitor C12 is connected in parallel between the side a and b of AD5263 digital regulation resistances；The AD5263 numerals current potential The W ends of the device normal phase input end phase after polarity free capacitor C13, resistance R10, resistance R11 with AD829 operational amplifiers successively Even, the normal phase input end of AD829 operational amplifiers is also grounded after polarity free capacitor C15, AD829 operational amplifiers it is anti-phase Input is connected between resistance R10 and resistance R11 after being connected with output end after polarity free capacitor C14, and AD829 computings are put The positive power source terminal and negative power end of big device connect positive 12V voltages and negative 12V voltages, the output end warp of AD829 operational amplifiers respectively The normal phase input end that polarity free capacitor C16 is crossed with LM3886 chips is connected, and the normal phase input end of LM3886 chips also passes through resistance It is grounded after R12, the inverting input of LM3886 chips is connected by resistance R13 with the output end of LM3886 chips and anti-phase input End is also grounded after resistance R14, and the positive power source terminal and negative power end of LM3886 chips connect positive 12V voltages and negative 12V electricity respectively Pressure, the earth terminal ground connection of LM3886 chips, the output end of LM3886 chips are connected with J1 joints.With traditional frequency synthesizer phase Than sine wave signal occurs circuit and uses Direct Digital Synthesizer (Direct Digital Synthesizer) DDS Digital technology realizes that DDS has the advantages that high accuracy, high-resolution, low harmony wave interference, using direct digital frequency synthesis technology Produce that frequency spectrum is pure, superaudio sine wave signal of amplitude stability, this signal passes through power amplification, pure stabilization is provided for filament Excitation power supply.

Preferably, the J1 joints are connected using twisted-pair feeder with discharge-tube amplifier filament.

Preferably, as shown in Figure 3 and Figure 4, the cpu circuit includes STM32 chips and its peripheral circuits, the STM32 Pin 9, pin 11 and the pin 13 of chip are connected with DDS chips AD9833 pin 8, pin 7 and pin 6 respectively, STM32 cores The pin 10 and pin 12 of piece are connected with the pin 13 and pin 16 of AD5263 digital regulation resistances respectively, the AD5263 numerals electricity The pin 11 and pin 12 of position device are connected with DDS chips AD9833 pin 6 and pin 7 respectively.

Preferably, as shown in figure 5, the power circuit includes transformer T1, rectifier bridge BG1, polarity free capacitor C20, nothing Polar capacitor C21, polarity free capacitor C22, polarity free capacitor C23, π type LC wave filters, polarity free capacitor C4, polarity free capacitor C5 With LT1117 voltage-stablizers, the π types LC wave filters include polar capacitor E20, polarized electric capacity E21, polarized electric capacity E22, Polarized electric capacity E23, inductance L1 and inductance L2, the transformer T1 primary side access 220V electric mains, transformer T1's Secondary side is connected with rectifier bridge BG1 input, rectifier bridge BG1 positive output end respectively one end with polarity free capacitor C20, have Polar capacitor E20 one end is connected with inductance L1 one end, the other end of the inductance L1 respectively with polarized electric capacity E21 one End, polarity free capacitor C21 one end are connected with positive 12V voltage output ends, rectifier bridge BG1 negative output terminal respectively with nonpolarity electricity One end, the polarized electric capacity E22 one end for holding C22 are connected with inductance L2 one end, and the other end of the inductance L2 is respectively with having Polar capacitor E23 one end, polarity free capacitor C23 one end are connected with negative 12V voltage output ends, and polarity free capacitor C20's is another One end, the polarized electric capacity E20 other end, the polarized electric capacity E21 other end, the polarity free capacitor C21 other end, nonpolarity The electric capacity C22 other end, the polarized electric capacity E22 other end, the polarized electric capacity E23 other end and polarity free capacitor C23 The other end is grounded after being connected；The voltage input end of the LT1117 voltage-stablizers respectively with positive 12V voltage output ends and nonpolarity electricity The one end for holding C4 is connected, the earth terminals of LT1117 the voltage-stablizers other end with polarity free capacitor C4, polarity free capacitor C5 respectively One end is grounded after being connected, and the voltage output end of LT1117 voltage-stablizers is defeated with polarity free capacitor the C5 other end and 3.3V voltages respectively Go out end to be connected.

Preferably, the secondary side neutral ground of the power transformer T1.

By sine wave signal chip AD9833, the soft electrification circuit AD5263 of digital regulation resistance, low pass occur for the utility model Wave filter AD829, power amplification circuit LM3886, cpu circuit STM32 and power circuit are formed.Sine wave caused by DDS chips Signal, by filtering out higher hamonic wave into second order Butterworth LPF after digital regulation resistance partial pressure, obtain 25KHz width Stable sine wave is spent, power amplification is carried out into the amplifier that LM3886 is formed afterwards, produces 6.3VRMS, 25KHz sine Ripple provides driving voltage for electron tube heater.

1. sine-wave generator：

Sine wave is generally represented with its amplitude：A (t)=sin (ω t).But, this sinusoidal wave is non-linearity curve, Therefore unless building by being segmented, otherwise it is not easy to generate.On the other hand, angle information is inherently linear.That is, In each unit interval, phase angle can rotate fixed angle.Angular speed depends on signal frequency, the π f of namely ω=2.Sine wave Generator by ANALOG companies Direct Digital Synthesizer (Direct Digital Synthesizer) chip AD9833 is formed, and the chip supports various simple and complicated modulation schemes completely.These modulation schemes are completely in numeric field Realize so that DSP (Digital Signal Processing) technology can be used accurate and easily realize the modulation algorithm of complexity.AD9833 bags Containing 10 high impedance, current source DAC.The DAC receives the point-by-point numerical value of sine wave from SINROM (sine table), and is converted Into corresponding analog voltage.The DAC is configured to single-ended mode of operation.The DAC can produce an output voltage, and its representative value is 0.6V p-p.Stabilized power source needed for the voltage reference offer AD9833 analog portions and numerical portion of chip internal.DDS chips Internal sine table has at as many as 4096 points per cycle, and the harmonic wave of its caused waveform is significantly larger than 25KHz and is very easy to filter out, and The sine wave spectrum of multiple spot synthesis is very pure, and waveform stabilization degree is very high as caused by crystal oscillator, internal reference circuit and D/A Converter make it that sinusoidal amplitude is highly stable.

2. digital regulation resistance

AD5263 is 256, digital control variable resistance, can be achieved to adjust with potentiometer or variable resistor identical electronics Function.Between A ends and vernier W or B ends and vernier, each VR provides a complete programmable resistance values.A to B fixes termination electricity It is 1% to hinder 20k Ω tolerances.Powered using highest+15V or ± 5V power supplys.In system electrification, vernier position default setting is middle amount Journey.After upper electricity, VR verniers position can be programmed setting by a SPI compatible type serial data interface.

3. power amplifier

LM3886 is the high-power audio amplification circuit that NS companies of the U.S. release, and its power is larger, in specified work Make the maximum continuous undistorted mean power up to 68W under voltage, equally protect work(with fairly perfect overvoltage, overcurrent and superheat Can, most valuable is the function of rush of current when it has an automatic anti-switching on and shutting down, and this feature is protected to electricity on electron tube heater Shield is particularly valuable.Other features have：Small (the total distortion plus noise of output power (continuous power output 68W), the distortion factor< 0.03%), defencive function (including protect by impact when overvoltage protection, overtemperature protection, current limit, temperature limiting, Switching Power Supply Shield, noise elimination function) it is complete, peripheral cell is few, makes debugging easily, stable and reliable in work.There is non-constant width through surveying LM3886 Bandwidth, survey and can't see distortion with oscillograph observation on 100KHz sine wave pure resistor loads, in the utility model It is smaller that LM3886 works in 25KHz distortions, fully meets application.

Circuit analysis：

Sine-wave generator is made up of U1 (AD9833) and peripheral components, is connected by SPI mouths with CPU, CPU, which passes through, to be configured The sine wave that register inside U1 produces 25KHz is exported by 10 pin, access digital regulation resistance U2 A pin, in the control of program Lower to produce an amplitude by 0 to 0.6Vp-p sine wave, digital regulation resistance is when upper electric by zero to maximum slowly varying generation The soft power up that one filament slowly powers up.To protect filament from heavy current impact, extend the life of tube.U2 output pins The second order Butterworth LPF that the cut-off frequency of W access R10-11, C14-15, U3 compositions is 40KHz, the Q of wave filter It is worth for 0.707, multiplication factor 1, exports through C16, power amplification is carried out into U4 (LM3886), in order to improve effect in circuit Rate, not using mu balanced circuit, it is contemplated that inherently a kind of power amplifiers of LM3886, there is very high PSRR (PSRR Representative value is 120dB), it can be approximately considered, the stable then output signal of input signal is also stable, so completes friendship indirectly Flow the filament AC voltage-stabilizing under electric power thus supplied.Power amplifier is the in-phase amplifier connection of standard, and multiplication factor is determined by R13, R14, Multiplication factor calculation formula is G=(1+R13/R14), changes R13, R14 ratio and can change output voltage, output voltage by Input voltage and multiplication factor G are determined, unrelated with mains fluctuations, because input voltage is by reference power supply and D/ in U1 piece A converters export, and itself is highly stable, and equivalent to AC voltage-stabilizing is completed, filament supply is exported by J1, and filament line is using double Twisted wire is attached, and using two groups of Filament Winding senses of current on the contrary, being grounded with reference to power transformer, electric field is cancelled out each other, Ultrasonic alternating current impression noise can effectively be suppressed.

Power unit of the present utility model is whole mainly by the power transformer T1 using transformer center tap earthing mode Bridge BG1, and π type L, C wave filters E20, L1, E21, E22, L2, E23 composition are flowed, positive-negative power, LT1117 voltage stabilizings are provided for system Device U6 provides power supply for 3.3V voltage-stablizers for the numerical portion of system.The determination of supply voltage：The utility model is described as filament Voltage is 6.3V RMS, then voltage peak is：6.3*1.414=8.9Vp actual power voltage takes 12V-14V.The power supply of power amplifier Voltage, it not be higher by too much, otherwise efficiency is low, and heating is serious.

CPU part of the present utility model is responsible for the digital current potential of control using the current most common bit CPUs of STM32-M0 32 Device and DDS chips, circuit are connected as standard connection, will not be repeated here.

Implementation process of the present utility model：After CPU electrification resets, initialize peripheral chip, and by digital regulation resistance as Minimum, it is zero to make output voltage, configures DDS chips afterwards, exports 25KH sine waves, and in 10 seconds, by digital regulation resistance Maximum gradually is adjusted to, output voltage is reached 6.3V, completes the soft upper electricity of filament.

Practical application explanation：

1st, it is 6.3V that the utility model, which is described as filament voltage, electron tube multi-filament of the same race can be connected during actual use Use, improve the output voltage of power amplifier, reduce output current, to reduce power amplification distortion, and heating, at this moment power supply should be made accordingly Adjustment, but it is noted that not exceeding the peak power of power amplifier, due to continuous work, power amplifier must have enough radiatings.

2nd, because filament supply current is big, frequency is high, it is necessary to which, using the twisted-pair shielded wire for having enough line footpaths, screen layer should can It is abutted against ground.

In addition, application of the present utility model be not limited to the technique of the specific embodiment described in specification, mechanism, Manufacture, material composition, means, method and step.From disclosure of the present utility model, as one of ordinary skill in the art Will readily appreciate that, for current technique that is existing or will developing later, mechanism, manufacture, material composition, means, Method or step, the function or obtain substantially that wherein their execution are substantially the same with the corresponding embodiment of the utility model description Identical result, they can be applied according to the utility model.Therefore, the appended claims for the utility model be intended to by These techniques, mechanism, manufacture, material composition, means, method or step are included in its protection domain.

Claims (6)

1. a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament, it is characterized in that, including sine wave signal generation Circuit, digital regulation resistance, low pass filter, power amplification circuit, cpu circuit and power circuit, described sine wave signal hair Raw circuit, digital regulation resistance, low pass filter, power amplification circuit are sequentially connected, and sine wave signal occurs caused by circuit just String ripple signal obtains 25KHz amplitude stabilization by filtering out higher hamonic wave into low pass filter after digital regulation resistance partial pressure Sine wave ingoing power amplifying circuit carries out power amplification, and the sine wave for producing 6.3VRMS, 25KHz is discharge-tube amplifier lamp Silk provides driving voltage；Circuit occurs with sine wave signal respectively for the cpu circuit and digital regulation resistance is connected, for controlling just String ripple signal generating circuit produces sine wave signal and provides stable excitation power supply and by digital electricity for discharge-tube amplifier filament The voltage of position device control discharge-tube amplifier filament slowly rises；The power circuit is electric to provide work for servo circuit Source.

2. a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament according to claim 1, it is characterized in that, The sine wave signal occur circuit include 25M crystal oscillators, DDS chips AD9833, polarized electric capacity E10, polarity free capacitor C10, Polarity free capacitor C11, polarity free capacitor C12, the digital regulation resistance use AD5263 digital regulation resistances, the low pass filter Including polarity free capacitor C13, polarity free capacitor C14, polarity free capacitor C15, polarity free capacitor C16, resistance R10, resistance R11 and AD829 operational amplifiers, the power amplification circuit include resistance R12, resistance R13, resistance R14 and LM3886 chip；

The VCC pin and H pins of the 25M crystal oscillators connect 3.3V voltages, GND pin ground connection, OUT pins and DDS chips respectively AD9833 pin 5 is connected；The pin 1 of the DDS chips AD9833 is connected by polarity free capacitor C11 with pin 1 to be followed by 3.3V voltages, pin 1 are also grounded after polarity free capacitor C10, and pin 3 is grounded after polarized electric capacity E10, the He of pin 4 Pin 9 is grounded after being connected respectively with the B ends of AD5263 digital regulation resistances, and pin 10 is connected with the A ends of digital regulation resistance；The nothing Polar capacitor C12 is connected in parallel between the side a and b of AD5263 digital regulation resistances；The W ends of the AD5263 digital regulation resistances are successively It is connected after polarity free capacitor C13, resistance R10, resistance R11 with the normal phase input end of AD829 operational amplifiers, AD829 fortune Calculate amplifier normal phase input end be also grounded after polarity free capacitor C15, the inverting input of AD829 operational amplifiers with it is defeated Go out after end is connected and be connected to after polarity free capacitor C14 between resistance R10 and resistance R11, the positive electricity of AD829 operational amplifiers Source and negative power end connect positive 12V voltages and negative 12V voltages respectively, and the output end of AD829 operational amplifiers passes through nonpolarity electricity Holding C16 with the normal phase input end of LM3886 chips to be connected, the normal phase input end of LM3886 chips is also grounded after resistance R12, The inverting input of LM3886 chips is connected by resistance R13 with the output end of LM3886 chips and inverting input is also by electricity It is grounded after resistance R14, the positive power source terminal and negative power end of LM3886 chips connect positive 12V voltages and negative 12V voltages, LM3886 cores respectively The earth terminal ground connection of piece, the output end of LM3886 chips are connected with J1 joints.

3. a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament according to claim 2, it is characterized in that, The J1 joints are connected using twisted-pair feeder with discharge-tube amplifier filament.

4. a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament according to claim 1, it is characterized in that, The cpu circuit includes STM32 chips and its peripheral circuits, and pin 9, pin 11 and the pin 13 of the STM32 chips are distinguished Be connected with DDS chips AD9833 pin 8, pin 7 and pin 6, the pin 10 and pin 12 of STM32 chips respectively with AD5263 The pin 13 of digital regulation resistance is connected with pin 16, the pin 11 and pin 12 of the AD5263 digital regulation resistances respectively with DDS Chip AD9833 pin 6 is connected with pin 7.

A kind of 5. servo electricity of superaudio sine wave electronic pipe amplifier filament according to Claims 1-4 any one Road, it is characterized in that, the power circuit includes transformer T1, rectifier bridge BG1, polarity free capacitor C20, polarity free capacitor C21, nothing Polar capacitor C22, polarity free capacitor C23, π type LC wave filters, polarity free capacitor C4, polarity free capacitor C5 and LT1117 voltage stabilizing Device, the π types LC wave filters include polar capacitor E20, polarized electric capacity E21, polarized electric capacity E22, polarized electric capacity E23, inductance L1 and inductance L2, the transformer T1 primary side access 220V electric mains, transformer T1 secondary side with it is whole Stream bridge BG1 input is connected, rectifier bridge BG1 positive output end one end with polarity free capacitor C20, polarized electric capacity respectively E20 one end is connected with inductance L1 one end, the other end of inductance L1 one end with polarized electric capacity E21, electrodeless respectively Property electric capacity C21 one end is connected with positive 12V voltage output ends, and rectifier bridge BG1 negative output terminal is respectively with polarity free capacitor C22's One end, polarized electric capacity E22 one end are connected with inductance L2 one end, the other end of the inductance L2 respectively with polarized electric capacity E23 one end, polarity free capacitor C23 one end are connected with negative 12V voltage output ends, the polarity free capacitor C20 other end, have pole The property electric capacity E20 other end, the polarized electric capacity E21 other end, the polarity free capacitor C21 other end, polarity free capacitor C22 The other end, the polarized electric capacity E22 other end, the polarized electric capacity E23 other end are connected with the polarity free capacitor C23 other end After be grounded；The voltage input end of LT1117 voltage-stablizers one end with positive 12V voltage output ends and polarity free capacitor C4 respectively It is connected, the earth terminals of LT1117 voltage-stablizers is after the other end with polarity free capacitor C4, polarity free capacitor C5 one end are connected respectively Ground connection, the voltage output end of LT1117 voltage-stablizers are connected with polarity free capacitor the C5 other end and 3.3V voltage output ends respectively.

6. a kind of servo circuit of superaudio sine wave electronic pipe amplifier filament according to claim 5, it is characterized in that, The secondary side neutral ground of the power transformer T1.