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Questions tagged [diodes]

Diodes are semiconductor components made from a P-type and N-type silicon material, that allows current to only flow in one direction.

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Diode substitution for FMXG26S

I been hunting for an equivalent for a Diode in TV Power Supply - its a FMXG26S. Does anyone have any idea of an equivalent? Or where I can look one up? The datasheet advises the following for the ...
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22 views

Loading an AC generator with DC Chopper + resistor

We're in kind of a bind at work and looking for easiest / cheapest way to load an AC generator (Synchronous permanent magnet machine). We have access to a big 300A Mosfet module along with it's ...
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35 views

Will my zener diode work again with a polyfuse after a overvoltage?

I am trying to make a simple overvoltage & current limiting circuit for my PCB. I made the following circuit. The zener will break down and conduct current to ground. Since its resistance has ...
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1answer
32 views

Using Diode As a Solar/Lightbulb Cell

...hi :) a few days back I saw this Instructables.. https://www.instructables.com/id/Using-Diode-As-a-Solar-Cell/ ...so I started to experiment how this can be used to charge a cellphone or a ...
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226 views

Parallel Power Supplies with Ideal Diodes

I'm working on a project that operates at 5v - and can draw UP to 10 amps. Under normal conditions, it won't be doing that - probably closer to 3 amps, and (if configured for low-power) only 450mA or ...
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23 views

Zener diodes multiple breakdown voltages

How could there be zener diodes with different breakdown voltages since the chemical bond of the Si atom with the B- atom has the same strength in all occasions?
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2answers
56 views

Thévenin's Theorem Example

I just started learning Thévenin's Theorem. My textbook gives the following example: I'm referring to online sources such as this to complete this problem. However, all of the circuit diagram ...
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1answer
60 views

Use zener diode as regular diode

I have a circuit that uses regular diodes, and I only have zener diodes in hand. As I understand, zener will conduct after a certain voltage in reverse, so all I have to do, is pick a voltage that is ...
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50 views

Sizing Flyback Diode

I'm working on a project to run a 12 volt 12 amp DC gearmotor via PWM output from a controller. I am using a Crydom solid state relay to power and motor and trying to figure out what diode is correct ...
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What I mean was that, in a diode semiconductor you know we have anode edge and cathode edge, [closed]

What I mean was that, in a diode semiconductor you know we have anode edge and cathode edge, for example now there is two diode and anode edge of the first diode connected to the cathode side of the ...
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48 views

Can an electron flow if anode lead and cathodes lead are on Same path.? [closed]

Can a current flow if anode lead and cathodes lead are on Same path.
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Need help wiring low beam and high beam headlights [migrated]

New aftermarket headlights on my daughter's truck have separate lights for low and high beams. I would like to wire them together so the low beam will still work independently, but they both will come ...
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34 views

Clamper circuit, how to apply kirchhoff when the diode is turned around?

in this clamper circuit it's easy for me to determine the output waveform: This is how I do it: In the positive half cycle, the diode is forward biased with a drop of 0.7 V, so the positive half ...
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3answers
135 views

Why does a capacitor charge faster when there is a diode connected?

In an series RC circuit why does a capacitor charge faster when there is a diode connected in parallel with the resistor? I tested on an oscilloscope, using a square signal and this is what I got. ...
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45 views

How the diode mode of a multimeter works

First of all, I'm new to board repair, but I would like to learn more so I decided to watch a lot of videos to learn. However, I can't find any answer to the questions below about the diode mode. ...
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1answer
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Schottky datasheet - divergence in Vf / If diagram vs “pulse test” table values

while looking at datasheets for clamping schottky diodes, I noticed that the values that manufacturers state in their tables ("Pulse test: tp < 300 µs; delta < 0.02.") are different from the ...
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1answer
31 views

Diode Depletion Region Forces

I'm currently doing some independent research on silicon based devices and I have come up with one question I can't seem to find the answer to elsewhere. I understand that when an n-type and p-type ...
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2answers
71 views

Load resistance in voltage regulator

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\$. simulate this circuit &...
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1answer
35 views

Create a polar cap with a diode?

I'm trying to order components, so I can make a board following this circuit. My problem is, I cannot find any 0.1uf capacitors, that are rated at 275VAC. The highest voltage I can find, in stock, is ...
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1answer
54 views

Voltage Multiplier Problem

I´m working on a voltage multiplier with 5 stage, i´m using the same capacitor and i think that my problem is the current load but i actually think that with a resistor in the output of the multiplier ...
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0answers
44 views

Can anyone identify this diode? S69D

I’m attempting to repair a totally dead Panasonic SC-HC30DB and have found a faulty diode in the secondary part of the SMPS. However, I can’t identify this diode marked S69D as you can see from the ...
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25 views

trying to ID a component Diode with PJO489 or PJ0489 and then EXP its a power dioide on a 24vDC psu

Hello I need to Identify this component the ruler is in mm its part of a control board and goes between the 24v input and the negative cathode side of the LEDs on the control panel. The cathode side ...
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1answer
19 views

ESD diode with zener configuration is equivalent to a circuit containing diode, transistor and zener diode, so how this could be equivalent

please tell me in the following link (https://www.onsemi.com/pub/Collateral/ESD9101-D.PDF), the ESD diode with zener configuration is equivalent to a circuit containing diode, transistor and zener ...
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1answer
40 views

Where does an IN5408 diode go in a hobby motor, on/off switch and AA battery holder setup?

I was told I need to add an IN5408 diode in the following setup but I am unsure where it goes. 2xAA battery pack Positive to On/Off Switch (simple open close circuit switch) To small hobby motor ...
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39 views

Powering multiple Laser Diodes

Hi I am working on a project that has 6 laser diodes. each pair has different voltage requirements. They are 7V-10V, 3V-5V, and 3V-5V. any suggestions to how I could power each together with one board?...
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1answer
47 views

Current through a diode changes for the same forward voltage in two circuits

In LTspice IV, I am simulating a 1N914 diode behavior in response to a variable current source in two circuits. One circuit has just the current source and the diode, and the other has the current ...
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18 views

Controlling circuit for 30A 72vdc to 12vdc voltage reducer

I am installing a 72vdc to 12vdc voltage reducer in my off road electric cart (golf cart on steroids) to run some LED light bars and a horn. The input of the reducer is constant 72vdc direct from the ...
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47 views

Sizing capacitor in capacitor-diode charge-pump circuit

How I should calculate the capacitor for a frequency of 200k and my output have to be 5 times my input. I know the voltage doubler circuit but in this case i dont know how to do this.
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1answer
53 views

Why does not all the current flows through Zener diode?

Let's assume the following circuit, where Zener diode is used as a voltage regulator. R16 (R18 later) is the load. When the input voltage is sufficiently high for Zener diode to be reverse-biased, ...
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1answer
38 views

Is there any easy and systematic way to analyse circuits containing opamp and multiple diodes?

simulate this circuit – Schematic created using CircuitLab For instance the circuit above.I need a more systematic procedure then hit and trial. Diodes have a cutin voltage of .7V and show ...
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1answer
21 views

Barrier voltage and temperature of a PN junction

Why does the barrier voltage of a PN junction decrease by increasing temperature ? Please if possible , i want to understand the inner physics of what happens
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2answers
100 views

Forward voltage across the diode

If the diode's dynamic resistance was zero , will not we be able to increase the voltage across the diode above 0.7 v ? (I am assuming forward bias ) I am asking this question because my book ( ...
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58 views

Wiring a led and light bulb 120V

I am trying to wire a 120V light socket and one led to a three way rocker switch so one way the led comes on the other way the light bulb comes on. I don't know how to get the 120V down to the 3....
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3answers
109 views

How do I solve the current of this circuit with a diode?

I am trying to calculate the current of the circuit but I am unable to find the correct answer. I was able to solve the same circuit without the diode witch gave me 2mA. I am unsure of what to do with ...
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19 views

ADS harmonic balance discrepancies with sawtooth waveform

I am using ADS for a simulation where I am biasing a diode with a sawtooth waveform. The sawtooth source provided by ADS, and 3 harmonics are specified There are different phase delays across the ...
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3answers
77 views

Confused with voltage doubler circuit

This is how the book explains the process: Let me consider the first 90° of the input, the capacitor charges up to the peak voltage less the diode drop of D1, D1 is forward biased and D2 is reverse ...
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1answer
44 views

In this semi-ideal photodiode, what would be the physical interpretation of this current?

A real photodiode can be expressed as a circuit made of several ideal components, it looks something like this: simulate this circuit – Schematic created using CircuitLab I copied it from here ...
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2answers
43 views

Question about diode clamper

I have 2 problems with diode clampers that I don't understand First, in this circuit for example: In the positive half cycle, the voltage across the diode is the diode drop of 0.7 V Then the ...
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1answer
80 views

Would this parallel LED lamp upset the working of the flywheel diode?

I'm using a solenoid with a fly-back diode 1N001 and a mechanical switch as in the below diagram: Now I want to add this 24V indicator lamp in parallel with the solenoid as shown above to indicate ...
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2answers
68 views

How to determine the correct polarity of the diode

I'm having trouble knowing when is the cathode negative or positive and vice verse ( I'm not talking about the symbol ) I'm saying, when do the polarities change? For example, look at these 2 pictures ...
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1answer
70 views

Is a diode needed for this simple mini solenoid circuit?

I am building a mini pinball machine, which is about 10x22cm. To drive the flippers I plan to use this 5v mini push/pull solenoid: https://www.sparkfun.com/products/11015 , along with momentary SPST ...
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1answer
75 views

Where can I buy normal diodes? [closed]

Firstly apologies for any naivete in this post. I am not an electrical engineer, I just have a problem I am trying to solve. I have a 12v power supply connected to a 5v "reducer" (which started off ...
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2answers
64 views

Diode behavior when reverse biased with small voltage

I'm designing a simple circuit to use a lithium-metal coin battery as a backup power supply, and I'm considering something simple like this: simulate this circuit – Schematic created using ...
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1answer
39 views

PIN-diode lowest operation frequency limitations

I have a need to implement RF switch for HF circuit (~10 - 30 MHz) and I've been browsing options for that. Electromechanical switch would of course work, but I want to consider other possibilities ...
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3answers
241 views

Adding Diodes to Transistor Astable Multivibrator; 1N5818 Schottky diodes work but 1N4148 diodes don't; can't figure out why

I am an avid electronics hobbyist, not an electronics engineer. I built a transistor-based astable multivibrator circuit and then fed its output to an op amp buffer amplifier which then drove an 8 ...
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0answers
48 views

Change 1N4007 diode Bridge rectifier to single component or IC

I have seen people have been using 1N4007 diodes bridge rectifier to convert AC power supply to DC. Is there any IC or Component to convert this. If yes, then any suggestions about component or data ...
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1answer
67 views

How do these diodes prevent opamp from saturation?

I cannot understand how the clamping diodes prevent opamp from saturation when the switch/FET is off in the following sample-and-hold circuit: I only know that if the negative feed back of an opamp ...
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0answers
24 views

20A 12V Load for lithium battery cycling tests - Car Battery + DC power supply with diode?

Ok I have searched, can't find anything. I have a high capacity lithium ion battery testing rig, and I have some iCharger 406 units that are doing the testing for me. That side works awesome, and I ...
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0answers
61 views

What is the difference between these two protection circuits?

I have seen both protection circuits used in various designs. The first just back to back diodes clamping a line, the other clamping the line to the system voltage rails. Whats the difference between ...
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1answer
50 views

Mosfet Gate-Source Zener [closed]

I want to confirm this circuit is going to work and ask how to calculate the zener voltage. The load is going to be driven by 30 volts, and the gate voltage is the same 30v, through an optocoupler.