Diode Definition and 571 Threads

A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other semiconducting materials such as gallium arsenide and germanium are also used.

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  1. M

    Understanding PN Junction Diodes: Vbi & Measuring Voltage

    During the processing of a PN junction diode when the Ptype material and the Ntype material are joined together. The holes tend to diffuse from the Ptype material to the Ntype material and conversly the electrons from the Ntype material diffuse from the ntype material to the ptype material...
  2. P

    How does Switch mode power supplies differ from diode rectification

    hey guys, the topic basically explains it...Can someone please help me out with this question...How does SMPS differ from diode rectification? Thanks jake
  3. G

    Controlling Sensor Through Labview: Role of Diode?

    Can you guys look at the attached file. I have a sensor hooked up to a plug box. My question is, i am suppose to control the sensor through labview. My question is, how does the diode play a role? I would technically send the commands to the 1st input right? and if i wanted to read data, i could...
  4. H

    Where Can I Find a Graph of the 1N4148 Diode Characteristics?

    Anyone knows where can I find graph(characteristics) of the 1N4148 diode. Is there any website that has large number of different graphs for transistors, diodes ?
  5. Q

    Understanding Diode Display on a C.R.O.

    i have to draw the c.r.o. display for a diode, is it just the same as for an a.c. input but with the parts that were below the x-axis, intead reflected in the x-axis?
  6. S

    I-V characteristics of a silicon p-n junction diode

    Hello all, I've been tasked with drawing the I-V characteristics of a silicon p-n junction diode and I've managed to do that fine. Now, I've been tasked with showing how this curve will vary with temperature (200-400 deg.c) and by illumination with light of photon energy greater than the...
  7. Q

    Redrawing Circuits for Diode Analysis: Is It Valid?

    in the diagram below, the voltmeters are as near to perfect as possible, the cell has negligible internal resistance. the red blob is a conducting diode, and the green blob is non-conducting. the coloured boxes are resistors. in order to work out the current through the red diode, is it ok to...
  8. N

    Diode Configuration in Protection Circuit: Nose-to-Nose or Tail-to-Tail?

    Hi All, I'm replacing a switch in a piece of equipment. I'm looking at the circuit diagram and the actual circuit, and I notice that the diodes in the circuit aren't wired as they are in the diagram.:smile: The HI signal is dc from 0-1 Volt and LO is ground. Is there going to be any...
  9. T

    What happens when you shortcircuit a pn diode?

    A thought experiment: (note that this comes from a student with only amateur experience in solid state physics) suppose you could shortcircuit a pn diode... ie you just link a wire between both ends, or maybe even bend the pn diode in a ring (so you'd have a n-surface between two p-surfaces...
  10. C

    A Commuter Diode Explanation Problem

    I have been trying to figure how a commuter diode effectively works in a circuit with a coil. I know that once the electric/magnetic field collapses in the coil after the current is cut to it that it induces a current in the opposite direction on the diode, which can only travel one way. But...
  11. S

    How can I determine the junction area of a diode?

    Hi Guys! How are u my friends? Well i want to ask u one important thing! Please tell me the way to find out the junction area of a diode Thanks in advance
  12. S

    How is the junction area of each diode calculated in this circuit?

    Hi Guys! My Question is this: Dsign the circuit of the fig: so that Vo= 3V when IL = 0 A AND Vo changes by 40mV per 1mA of load current. the value of R = 4.8Kilo ohms. find the juction area of each diode (assume all four diodes are identical) relative to a diode with 0.7 V drop at 1mA...
  13. S

    Transfer Characteristic of a diode

    Hi Guys: My question is this for the circuit in the 1st fig: sketch the transfer charcteristic "vo" versus "vI" the answer of this question is the 2nd fig. but i want to know that what is the logic behind this sketch or in other words how we can draw such a sketch. Thanks in advance
  14. Crumbles

    What is the relationship between a laser's gain curve and its natural linewidth?

    Can someone please explain what exactly the gain curve of a laser is? Is it exactly the same thing as the natural linewidth of the laser [a graph of intensity vs frequency] or am I off track? I found this graphhttp://www.phys.ksu.edu/perg/vqm/laserweb/Ch-5/C5s1p5.htm that tries to explain...
  15. 0

    How Does Electric Field Influence Current Flow in a PN Junction Diode?

    when it comes to pn junction in diode, p and n are doping semiconductors. if P and N semiconductor are contacting each other, some holes in P and some electron in N are combined. that is, they are recombined. this recombination caused the current, very small. I was wondering that...
  16. C

    Modulating a diode laser with sound

    http://www.eweek.org/site/DiscoverE/PDFs/middle/First%20you%20see%20it%20Then%20You%20Hear%20It.pdf In my Photonics & Fibre Optics class today, our lecturer showed us a "Modern day photophone" he created for an easy $15 AUD (1AUD = 80US cents) I did not have time to ask him how to make one...
  17. E

    How Can Temperature Affect the Breakdown Voltage of a Semiconductor Diode?

    The problem is an experiment has to be set up to investigate how the breakdown voltage (which occurs by a large reverse potential difference is applied to the diode, and the diode then passes a large current) of a semiconductor diode is affected by temperature. My problem is how can I vary...
  18. S

    Understanding Diode Output Waveform Reversal

    Sketch the output voltage as a function of time. The AC voltage source is V_{o}cos(\omega)t with V_{o} = 10V and \omega = 2000rad/sec. I have posted a diode circuit question in the attachment Ok, I think it should be a sine curve with a 10 V amplitude but am not too sure about the period...
  19. S

    What Are the Basics of OLED Technology?

    has anyone come across any website with good information on OLED technology. I'm not really looking for the technical details. What I?m interested in is a general overview of the technology. What it is advantage/disadvantages , applications, history. Stuff like that. i would really...
  20. U

    Physics Behind Generating a Small Current with a Diode

    If you put a diode in circuit with a piece of metal, heat the metal so the electrons start jiggling about the diode should let only the elctrons going in a certain direction through thus creating a small current. I read somewhere this does not work but it did not explain why, or does it work in...
  21. J

    How a Diode Works: Semiconductor Silicon Circuit

    How does a diode work? Or more precicely how does a semiconductor such as silicon only allow current to flow one way around a circuit?
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