Triode Tube Research Articles

On the Application of Thévenin Equivalent Circuits to the Analysis of Vacuum Tube Circuits

In this paper, we express Thévenin equivalent circuits seen looking into the terminals of the small-signal model of the vacuum tube triode in terms of the Thévenin equivalent circuits seen looking out of the other terminals and apply them to the analysis of the common-cathode, common-plate, and common-grid single-tube amplifier configurations, as well as a differential pair amplifier. This is an adaptation of equivalent circuit techniques for transistor circuits pioneered by Marshall Leach. The use of equivalent circuits can yield intuitive solutions that avoid solving sets of equations.

Optimal Extraction and Statistical Analysis of Physical Model Parameters for Nonlinear Properties of Triode Vacuum Tubes

The purpose of this paper is to estimate the manufacturing-related variation factor from the difference in variance and correlation of the high-precision physical model parameters for a miniature triode vacuum tube 5751 with an amplification factor of 70. The vacuum tube operating model used here is based on physical equations adapted to the large signal input behavior of vacuum tubes used in guitar amplifiers and incorporates the effect of modulation of the amplification factor. This improves the accuracy of the soft clipping and hard clipping characteristics that affect the spectrum of the distortion sound. In order to improve the accuracy of the extraction of such multivariate model parameters, we devised a new analytical formula. In addition, we devised an algorithm for sequential regression analysis of the simulated and measured values against the analytical equation, and all parameter extraction was performed automatically by a computer program. As a result, correlations between the parameters, which had not been found before, were confirmed, and it became clear that the manufacturing and assembly accuracy of the grid electrode strongly affected most of the physical parameters.

The First Transistor and how it Worked: It emerged from a combustible mix of brilliance and ambition

THE VACUUM-TUBE TRIODE wasn't quite 20 years old when physicists began trying to create its successor, and the stakes were huge. Not only had the triode made long-distance telephony and movie sound possible, it was driving the entire enterprise of commercial radio, an industry worth more than a billion dollars in 1929. But vacuum tubes were power-hungry and fragile. If a more rugged, reliable, and efficient alternative to the triode could be found, the rewards would be immense.

Statistical analysis of manufacturer difference for miniature triode tube characteristics based on physical model parameters

AbstractThe sound of the tube amp due to the harmonic distortion has been thought to depend not only on the vacuum tube type but also on the vacuum tube manufacturer and individual differences. However, quantitative differences in tube characteristics of the manufacturer have yet to be revealed. In this study, the characteristics of the triode 12 AX 7 of the five major manufacturers were analyzed based on statistical analysis of advanced physical model parameter sets. Tube characteristics were divided into three groups by cosine similarity and group clustering method. As a result, we succeeded for the first time quantitatively combining tube distortion characteristics and tube characteristics.

High Precision Model of Small Triode Tube Considering Grid-Bias Positive/Negative Transition State

High Precision Model of Small Triode Tube Considering Grid-Bias Positive/Negative Transition State

Physically Based Unified Modeling for a Series of Miniature Twin Triode Tubes

Physically Based Unified Modeling for a Series of Miniature Twin Triode Tubes

Carbon Nanotube Film Gate in Vacuum Electronic Devices.

A superaligned carbon nanotube (SACNT) film can act as an ideal gate electrode in vacuum electronics due to its low secondary electron emission, high electron transparency, ultrasmall thickness, highly uniform electric field, high melting point, and high mechanical strength. We used a SACNT film as the gate electrode in a thermionic emission electron tube and field emission display prototype. The SACNT film gate in a thermionic emission electron tube shows a larger amplification factor. A triode tube with the SACNT film gate is used in an audio amplification circuit. The SACNT film gate electrode in field emission devices shows better field uniformity. The field emission display prototype is demonstrated to dynamically display Chinese characters.

SPICE Modeling of Miniature Dual Triode Vacuum Tube for Audio Application

SUMMARYIn this paper, we describe novel high precision SPICE modeling for triode vacuum tube, which is attracting attention in electronic musical instruments continuously and recently in the field of audio systems. The advantage of proposed high‐precision modeling is that it is created considering the difference of space charge distribution originated from the difference of electrode distance between triode tube 12AX7 and 12AU7.It was found that the characteristic of the space charge change appears within the grid voltage range of minus 1 to plus 1 volt with respect to the grid current versus grid voltage Ig‐Vg curve. In this range, thermal electrons are accelerated from the initial velocity condition of the Maxwell distribution. Based on this analysis, the modulation model formula of the perveance value Gs, which is the key factor of the space charge, is obtained. Subsequently, we extended the model formula to the cathode current versus plate voltage Is‐Vp family curves with the grid voltage as a parameter in consideration of the perveance Gs modulation effects. Finally, Ig‐Vp family curve model equation is derived. Comparing the simulation results of the AC characteristics performed using the proposed model equation and the conventional SPICE model equation, the superiority of the new model equation was confirmed.

Characterization of Inductive loop coupling in a Cyclotron Dee Structure

Many of today's low to medium-energy cyclotrons apply RF power to the resonator structure (the dees) by inductive loop coupling through a feed-line driven by an RF transmitter employing a triode or tetrode power tube. The transmitter's output network transforms the tube's optimum load line (typically a few thousand ohms) down to Z0, typically 50 ohms. But the load-line is not a physical resistance, so one would not expect to see 50 ohms when looking back toward the transmitter. Moreover, if both the resonator's input and the transmitter's output are matched to Z0, then the coupled or working Q of the resonator is reduced to half that of the uncoupled Q, implying that half the power is being dissipated in the transmitter's output resistance- an inefficient and expensive solution for a high power RF application. More power is available if the transmitter's reverse-impedance is not matched to Z0, but this may result in misalignment between the frequency for correct forward match at the loop, versus the frequency for maximum power in the resonator. The misalignment can be eliminated, and the working Q maximized, by choosing the appropriate length of feed-line between the non-matched transmitter output and the matched resonator's input. In addition, the transmitter's output impedance may be complex, comprising resistance plus reactance, requiring a further process and means of measuring the output impedance so that an additional compensating length of feed-line can be incorporated. But a wrong choice of overall feed-line length- even though correctly load-matched at the resonator's operating frequency- can result in a curious degenerate condition, where the resonator's working Q appears to collapse, and the potential for transmitter overload increases substantially: a condition to be avoided!

High Precision Temperature Control System for an Oven-Controlled Crystal Oscillator

Environmental temperature is a highly influential factor regarding the stability of the crystal oscillator frequen- cy. Thus, a high precision temperature control system is critical for improving the frequency stabilization of crystal oscil- lators. This paper proposes a temperature control system, including a high sensitive thermistor, precision reference voltage source and an instrumentation amplifier for the temperature measurement and preamplifier. System level MCU— MSC1210 acts as a main controller, and a novel way of the interrupt + ribbon strategy is adopted to realize real-time task scheduling. The PID controller program is crafted with the help of the anti-integral saturated and bumpless trans- fer algorithms. The cascade control system with the heating current of negative feedback is then realized using the triode tube consumption heating style. The results show that the temperature and fluctuation of heat voltage have almost no ef- fect on the heating current when the heating system voltage fluctuates between 2.2 ~ 8V. Within those parameters, the temperature deviation remains within 0.01 degrees. Thus it can be seen that the high-performance temperature control sys- tem has a high anti-interference capability and a similarly high level of accuracy.

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

New Family of Wave-Digital Triode Models

A new family of wave-digital vacuum tube triode models is presented. These models are inspired by the triode model by Cardarilli , which provides realistic simulation of the triode's transconductance behavior, and hence high accuracy in saturation conditions. The triode is modeled as a single memoryless nonlinear three-port wave digital filter element in which the outgoing wave variables are computed by locally applying the monodimensional secant method to one or two port voltages, depending on whether the grid current effect is taken into account. The proposed algorithms were found to produce a richer static harmonic response, introducing comparable or less aliasing and requiring approximately 50% less CPU time than previous models. The proposed models are suitable for real-time virtual analog circuit simulation.

Radio-Frequency Electron Accelerators for Industrial Applications

Two types of radio-frequency electron accelerators are described in this article. They operate in the frequency range of 100–200 MHz and are energized with triode or tetrode tubes instead of klystrons. They can provide more powerful electron beams than typical microwave linear accelerators.

Polymer space-charge-limited transistor as a solid-state vacuum tube triode

We report the construction of a polymer space-charge-limited transistor (SCLT), a solid-state version of vacuum tube triode. The SCLT achieves a high on/off ratio of 3×105 at a low operation voltage of 1.5 V by using high quality insulators both above and below the grid base electrode. Applying a greater bias to the base increases the barrier potential, and turns off the channel current, without introducing a large parasitic leakage current. Simulation result verifies the influence of base bias on channel potential distribution. The output current density is 1.7 mA/cm2 with current gain greater than 1000.

Photochemical “Triode” Molecular Signal Transducer

A molecular "hexad" in which five bis(phenylethynyl)anthracene (BPEA) fluorophores and a dithienylethene photochrome are organized by a central hexaphenylbenzene unit has been prepared. Singlet-singlet energy transfer among the BPEA units occurs on the 0.4 and 60 ps time scales, and when the dithienylethene is in the open form, the BPEA units fluoresce in the 515 nm region with a quantum yield near unity. When the dithienylethene is photoisomerized by UV light to the closed form, which absorbs in the 500-700 nm region, the closed isomer strongly quenches all of the excited singlet states of BPEA via energy transfer, causing the fluorescence quantum yield to drop to near zero. This photochemical behavior permits the hexad to function in a manner analogous to a triode vacuum tube or transistor. When a solution of the hexad is irradiated with steady-state light at 350 nm and with red light (>610 nm) of modulated intensity, the BPEA fluorescence excited by the 350 nm light is modulated accordingly. The fluorescence corresponds to the output of a triode tube or transistor and the modulated red light to the grid signal of the tube or gate voltage of the transistor. Frequency modulation, amplitude modulation, and phase modulation are all observed. The unusual ability to modulate intense, shorter-wavelength fluorescence with longer-wavelength light could be useful for the detection of fluorescence from probe molecules without interference from other emitters in biomolecular or nanotechnological applications.

Design aspects of 13.56MHz, 1kW, CW-RF oscillator for plasma production

RF produced plasma has many applications in plasma processing and also it is useful in studying the fundamental characteristics of the plasma. A 1KW RF Hartley oscillator is designed and tested at 13.56 MHz. This has been built at RF section of Institute for Plasma Research by using EIMAC (3CX1200A7) triode tube. The RF source is operated in the grounded cathode mode. Triode 3CX1200A7 is operated in class AB and the feedback is Cathode grounded. The tube has sufficient margin in terms of plate dissipation and Grid dissipation that makes it suitable to withstand momentarily load mismatch. To optimize the RF source along with HVDC power supply many mechanical and electrical aspects have been thought of to enhance the overall quality of the system. This source mainly has three sections (The RF section, HVDC Power supply and soft start Filament Power supply). The system is compact and is housed in a 80 cm × 60 cm × 1800 cm aluminum panel. This paper describes the specifications, design criteria, circuit used, operating parameters of 1KW Oscillator along with HVDC power supply with necessary interlocks, tests conducted and results obtained of this 1 KW grounded grid Hartley Oscillator on 50 ohm dummy load. This system has been tested for 8 hours of continuous operation without any appreciable deterioration of the RF output power.

Videos Describing the Manufacture of a Triode Vacuum Tube (or Valve)

First Page

An experiment on thermionic emission: back to the good old triode

A simple experiment to study thermionic emission, the Richardson–Dushman equation and the energy distribution function of thermionic electrons emitted from a hot cathode using a triode vacuum tube is described. It is pointed out that such a distribution function is directly proportional to the first derivative of the Edison anode current with respect to the control grid voltage of the triode when the anode voltage is equal to zero. The energy distribution functions obtained are better described by the Fermi–Dirac law than by the Maxwell–Boltzman distribution law.

The Legacy of the CE and BMET: Safer Healthcare Technologies

The Legacy of the CE and BMET: Safer Healthcare Technologies

Polymer space-charge-limited transistor

A metal grid is sandwiched between poly(3-hexylthiophene) to form a solid-state version of vacuum tube triode, where the vertical space-charge-limited current is modulated by the grid potential. The Al grid contains random submicron openings formed by a nonlithographic method. The multilayer polymer structure is made by spin coating. The operating voltage of the polymer space-charge-limited transistor is 3V, and the current gain of 506 is obtained. The characteristics of the transistor can be tuned by the diameters and the density of the openings on the grid. Similar to the vacuum tube triode, the current follows a power law voltage dependence.