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. archaic

    Load resistance in voltage regulator

    Homework Statement [/B] I want to find the minimum resistance ##R_L## so as to maintain ##V_z##(voltage of the zener corresponding to the minimum current ##I_{z_0}##) across the same resistor ##R_L##. Homework Equations ##V_z##(voltage of the zener corresponding to the minimum current...
  2. Abimbola1987

    Measurement of vacuum diode electron flow

    Dear Sirs, After my theoretical post on vacuum diode electron flow, I decided to try and measure it physically. I didn't have a vacuum tube, so I improvised with some tungsten wire, aluminum sheets and some screws and the result was usable. Obviously the tungsten wire fails after some time due...
  3. Abimbola1987

    Understanding Electron Flow in Vacuum Diodes

    Dear Sirs I have been going through the "radiotron designers handbook", but I can't seem to find the answer to the doubt I have about the electron flow of the source Vp. Kindly consider the below two circuits, the difference is the polarity of Vf. Question: In both circuits, the electrons...
  4. Boltzman Oscillation

    Engineering What is the output voltage of this ideal diode circuit?

    Homework Statement Given the following circuit: what is the positive and negative peak values of Vo? vi has a frequency of 1kHz, peak of 5V, and is a sine wave. Homework Equations x(t) = Vsin(2(pi)*f*t) KCL, KVL, etc. The Attempt at a Solution [/B] I made Vi to be 5sin(2(pi)1000t) during...
  5. R

    Best way to bond laser diode materials together

    chemical vapor deposition, Molecular beam epitaxy or magnetron sputtering What is the best way to bond GaAs to the intrinsic layer of a laser diode? I am planning on building a refactory oven on a concrete pad this summer once I clear of one side of my yard. There is just no way around it...
  6. Z

    Help Understanding Circuit Requirements for Conducting Diode

    Hi all. I need some help with the circuit attached. For the diode to conduct, at point X the voltage must be 0.6V minimum. There is an equation to find the minimum required voltage input, Vin to give 0.6V at X. What I don't understand is the right hand side of the equation; why is it...
  7. Javier Lopez

    High Power SCR Driver Design for Plasma Compression Coil Activation

    I have made following design to drive two high power hokeypuck SCRs to activate a Plasma compression coil. As long as catode falls below 0V, I do not know if it is needed to insert diodes from the optoisolated driver A1 (and A2) and the limiting current resistor R1 (and R2):
  8. volnei_cipriano

    Photoelectric effect in the study of a luminous diode (LED)

    I have studied the operation of light Diodes in the basic electronics course in my graduation and I had a question! Light Diodes (LEDs) are semiconductor materials with P-N junctions and that when energized emit visible light. I understand that the process of light emission when applying a...
  9. Wrichik Basu

    How does a voltage regulator differ from a zener diode?

    I am making a circuit with Arduino. It is known that the recommended power supply of an Arduino is 7V - 12V. I am going to use a 9-0-9 (230V to 9V) transformer, convert the stepped down voltage to DC, and feed it into the Arduino through the Vin pin. Now, there are chances that the input AC may...
  10. HotFurnace

    Electric Potential Distribution in a Vacuum Diode

    Homework Statement This problem is belonging to a book, which is material for Vietnamese students who will take part in IPhO (International Physics Olympiad). Since this problem is written in Vietnamese, I will try my best to translate it to English: A vacuum diode consists of two parallel...
  11. A

    Semiconductor substrate/Al_Comsol

    I have a semiconductor substrate and a metal. The metal is coated on substrate then a voltage applied. how can i simulate this in Comsol software.
  12. T

    Why Don't We Add Potentials in a Forward-Biased PN Junction?

    If two batteries are connected such that positive terminal of one is in contact with negative terminal of other then we add the potentials so the potential will then be their sum. Similarly if a battery is connected to a pn junction diode such that positive terminal is connected to negative...
  13. Hydrous Caperilla

    B Forward Biased Diode: Potential Rise vs Battery

    If a diode is connected with P junction with higher voltage and N with low voltage then why is there a potential rise as opposed to the decrease in potential like in battery?
  14. B

    A Interface states in a PIN diode

    Is the equation used to determine the density of interface states in schottky diodes from capacitance- frequency data applicable to PIN junctions?
  15. TheComet

    Series diode and a low power device

    I'm designing a device that consumes 450nA in idle (up to 2mA peak) and the maximum allowed voltage is 3.3V. The power is supplied by a battery with a voltage of 3.6V. One of the problems I've run into is: All LDOs I could find have a quiescent current consumption (Iq) greater than 450nA. The...
  16. M

    Hi, can somebody help to measure varicap diode

    Hello to everobody, i need help how works varicap can somebody explain how it works, how to measure i have bb205 VARICAP, i try to search on internet but i don't find something good, to learn thanks
  17. akaliuseheal

    How do I calculate the voltage of a diode in a simple electronics circuit?

    Homework Statement It's simple problem but I get stuck while calculating the VD. Currents and voltages in the circuit are required. So V, VD and I Homework EquationsThe Attempt at a Solution Since VA<VK I would assume that diode is OFF and then the diode can be represented by break. Upon...
  18. Pattarasak

    I How to calculate the photons/pulse of Laser diode?

    Hello everyone, I'm an Undergrad and I'm trying to set the Quantum key distribution experiment by using weak laser pulses(the laser diode with attenuated filter). but I don't know how to calculate the photon number per pulse. Can anyone tell me how to calculate the photon number per pulse...
  19. J

    Why is there a diode between two sources?

    I have a situation like on picture in attachment. I want to know, why I have a diode between two sources? What will happen without diode? Thank you.
  20. kostoglotov

    Diode Question: need to understand why my approach is wrong

    Homework Statement A screenshot of the problem: imgur link: https://i.imgur.com/ljtoclm.png Homework EquationsThe Attempt at a Solution My first attempt at the solution was this: imgur link: https://i.imgur.com/TJcvOzy.jpg However, I have access to the worked solution, and it is...
  21. G

    I Relationship between the depletion region and the band gap of a diode?

    Hi, Lately I've been reading about a lab exercise in which Planck's constant is estimated using LEDs. Every procedure I've encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor's band gap) is equal to the threshold voltage multiplied by...
  22. N

    Conduction Angle of a Diode Circuit

    Homework Statement I am trying to prove that the diode conducts between the expressions shown here: Homework Equations I know that Vo = Vpsin(wt) and the only information i know about the diode is it has a turn on voltage of Von. The Attempt at a Solution I have tried to plug the variables...
  23. H

    Motorcycle starter safety circuit

    I don't know if it's the same for a car but bikes uses a starter relay to set off a starter motor which cranks the engine. Bikes have a side stand for you to lean the bike against when stationary. In case the rider tries to start the bike with side stand deployed (could cause crash if forget to...
  24. Pushoam

    Zener Diode On: Understanding Current Flow in a Circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I assume that the zener diode is on. For this the current flowing through 1k##\Omega ~~i.e. ~~I_1## should be grater than the 3k##\Omega## i.e.##I_3##. ##I_3= 10/3~ mA \\I_1 = 4 ~mA## Clearly,##I_1 > I_3##. So, there is some...
  25. Pushoam

    Is the Resistance of a Diode Higher in D.C. or A.C.?

    Homework Statement Homework EquationsThe Attempt at a Solution Considering I- V characteristics graph, the slope for D.C. resistance is lower than that of the A.C. resistance. Now, the resistance is inverse of the corresponding slope. So, D.C. resistance should be more than A.C. resistance.
  26. J

    What's that diode in a solar panel for?

    Solar panels come with a diode like in diagram A what does this accomplish as I always hook them up like in diagram B
  27. Brandon91man

    Electrical DIY Solar Power System: Questions & Answers

    Hello, I've been building my own solar panel system and throughout this process I've accumulated a lot of questions. If anyone could help answer them I would greatly appreciate it! First I'll start off explaining what I have. A polycrystalline solar panel 17V 2.2A and a mono crystalline panel...
  28. R

    12V diode combiner circuit question

    Hello, I'm currently doing an electrical refit on a 29' Bristol. I have an anchor/steaming light for the top of the mast. I'm connecting them to two separate single pole single throw breakers. My problem is that I need the steaming light (fwd light) to be able to come on indipendantly from the...
  29. satominari

    Why is there reverse current in diode equation?

    When deriving diode equation, it is assumed that there's no drift. But still, in the result, we have a reverse current which is a drift... I don't get where this comes from.
  30. M

    I Determining Appropriate Focal Length

    So I'm working on a project where we're deciding a new lens to use for our laser diode. I need to determine the appropriate focal length based on the equation: 1/ƒ = 1/μ + 1/σ where ƒ is our focal length, μ is the distance from the lens to image and σ is distance from lens to object. For the...
  31. Cocoleia

    Bridge rectifier transfer function

    Homework Statement I am asked to decide which one of these is the transfer function of a bridge rectifier I was thinking D, but my friend says D is for when there is only one diode. Can anyone explain what the right choice is and why? This is not homework, rather preparation for my final.
  32. d3thkn1ght

    Solving for Zener Diode Voltage

    Homework Statement I have a problem where I need to calculate vo (i.e. output noise) and VO (i.e. DC output voltage) different resistances in a circuit with a Zener diode. The diode is reversed biased but I don't know the Vz. I have the IV curve but can't seem to wrap my head around how to...
  33. M

    Setting up a circuit to drive a Laser Diode

    Hello fellow physics friends (alliteration: always a strong opener). I am writing today because I find myself struggling to complete something which ostensibly doesn't seem that difficult to the average physics undergrad working in a lab. However, electronics and circuits are definitely a...
  34. Anik Paul

    What is diode small signal resistance?

    I'm not realising this thing.
  35. Bassa

    How Do You Calculate Current in a Diode-Resistor Series Circuit?

    Helo, I am in an electronic course and we just started studying diodes. I am stuck on the following problem: Place a 100 ohm resistance in series with a diode, and plot current versus voltage across the series combination. I am also given the following values for the diode: n = 1, Is =...
  36. C

    Diode Analysis and Thevenins Theorem

    Homework Statement Homework EquationsThe Attempt at a Solution The correct answer is 0.25V. I'm getting 0.3335V[/B]
  37. T

    B Existence of depletion layer in contact surface

    in a P-N junction diode, in an equilibrium state, a depletion layer forms in the surface of contact of N type and P type. But the problem is, this layer is formed by diffusion of electron to a lower electron density zone. Why does it always have to form right in the contactt surface? when...
  38. T

    What thyristor, triac, diode, transistor for an amateur?

    Beginner here. Learning about electronics. I would like to play with a thyristor, triac, diode, transistor, diode bridge, etc. using 1,5-9V batteries, wires, multimeter. I am buying a breadboard too. What kind of these you recommend for that purpose? There is a wide variety on the shelves please...
  39. whatphysics

    Calculating Q points for diodes

    Homework Statement In Figure Q22, the empirical junction diode equation is : (eqn is in the picture attached) for both diodes D1 and D2, where VT = 26 mV at room temperature, n = 1, IS = 3.5 x 10-14 A, R1 = 600 Ω, R2 = 300 Ω, R3 = 200 Ω, VS = 9 V. Calculate the Q-points ID = _____ mA and VD =...
  40. whatphysics

    Finding the forward current of diode

    Homework Statement A Si diode is operated at the room temperature (27 °C). For a forward current of 1 mA, the voltage VD is found to be 0.9 V. If the VD is 1 V, the forward current = _____ mA. Given that nVT = 26 mV The answer is 46.81 Homework Equations Shockley diode equation? The Attempt...
  41. Cocoleia

    Ideal Diode Exam Prep: Problem & Solution Help

    Homework Statement I am trying to prepare for an exam that is tomorrow, my professor gave sample questions but did not give us any solutions or answers. I have trouble with this question: Homework EquationsThe Attempt at a Solution I don't know what to do. I would maybe try to figure out if...
  42. nothing909

    Calculating resistor for IGBT and choosing flyback diode

    Homework Statement On the circuit I've drawn up, how do I calculate a current limiting resistor for the gate of the IGBT? The IGBT being used is a stgp6nc60hd. Also, how would I go about choosing a flyback diode for the motor?
  43. Cocoleia

    Why is it not possible for D2 to be off in this diode problem?

    Homework Statement I am working on this problem, where I need to find I and V Homework EquationsThe Attempt at a Solution I know the right answer will be when D1(left) is off and D2(right) is on, we went over the solution in class. I wanted to do the 4 assumptions just to try to understand. I...
  44. M

    Calculate the Vout vs Vin characteristics for a diode circui

    Homework Statement Calculate the Vout vs Vin characteristics for input voltages of 5V to 10V peak.[/B] Homework EquationsThe Attempt at a Solution Would Vout simply be nothing because the diodes are connected in anti-parallel? Putting a volt probe at Vin and Vout gives something like: (Green...
  45. T

    Confusion about how KCL and KVL are used for diode circuits

    Homework Statement This is just one of the example problems in my book which is already solved for me, but I don't really understand their solution which I'll post here: They start out with assuming Vin is very negative, which makes D1 turn on and makes Vout=VD,on+Vin. THen they solve for...
  46. Cocoleia

    Diodes & Rectifiers: Homework Solutions

    Homework Statement I am practicing problems like this: where Vs=10V, R=2kohm, they say it is like a battery + ideal diode with VD=0.7V I have to sketch the transfer characteristic Vo=f(Vs) and draw the waveform of Vo(t) Homework EquationsThe Attempt at a Solution I am really unsure how to go...
  47. J

    Into capacitor, half wave rectifier diode conducts for?

    Homework Statement The time for which the diode conducts is Homework Equations Using integration and differentiation Vc = 1 / C integral (current)(dt) The Attempt at a Solution Vs = -Vc Vm sin(wt) = -Vc = - (1/C) integral (Idt) now differentiate both sides to get expression for I that is...
  48. Cool4Kat

    How did Roentgen rectify current in the first x-ray?

    Hi, I was studying Roentgen (and Crookes tubes) and realized that they used spark gap generators which sent out bursts of AC current. However, Crookes tubes work with one end being the cathode and one the anode. They did this before diodes so how did they ensure that one side was negative and...
  49. A

    B Why do RMS values change during rectification?

    Why RMS values change during half wave rectification, full wave rectification? And why does RMS value remain constant during smoothing?
  50. C

    Engineering Calculating Diode Current in R-V Circuit w/ Sinusoidal Input

    Homework Statement R = 1 kohm and Vs(t) is sinusoidal of (peak) amplitude 3 V. The diode is modeled by the series combination of an ideal diode and 0.7 V voltage source. For what percentage of time will the diode conduct? answer: 42.5 Homework EquationsThe Attempt at a Solution I'm...
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