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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23 views

series connected capacitor

simulate this circuit – Schematic created using CircuitLab How does the capacitor behave here? I tried and the led flashed. Does the capacitor work like a diode after charging?
64 views

Series diode instead of a flyback one

My question is can I use a diode in series with a MOSFET, instead of pusing it as a flyback diode. simulate this circuit – Schematic created using CircuitLab
82 views

I am working on a project that samples a 1 kHz signal @ 20 kHz, the signal is 5Vpp biased on +2.5V that way everything is fine. I want to make a protection schematics to work along my offset. I am ...
430 views

Reverse Voltage?

Sorry, I searched but could not find (or maybe understand) and exact answer to my question. I am a carpenter, not an Electrical Engineer. My passion is building things (almost anything) and ...
51 views

Designing a clipper circuit

Design a clipper circuit using 1N4148 general purpose diodes and a R = 1 kΩ to clip input signal voltages that are above 5.7 V or less than −0.7 V. Below is my schematic in which Vo<=Vdo + 5V and ...
1k views

Building an amplifier out of diodes

It is quite obvious that we can't build an amplifier out of resistors (because of their linearity). But is there a circuit theorem that states the impossibility of building an amplifier out of diodes (...
92 views

characterizations Id (Diode Current) - Vd (Diode Voltage) IN4728A

I´m graphic the diode voltage and the diode current, this graphic would have to give a no linear graphic. and my graphic is given this curve What is my error?
81 views

Multiple diode circuit has several solutions: which one to choose?

Here is very interesting discussion on this topic: Proof that every circuit with diodes has exactly one solution And this is my example: Let's start. We have 3 generic diodes with cut-off voltage = ...
35 views

Find and sketch the transfer function

This is the original circuit, we assume Vdo=0.7V, this is for when either of the diodes are on. We know both diodes cannot both be off because then no current would flow in the circuit. I become ...
764 views

LTSpice Zener diode bug?

I'm trying to design a circuit using a zener diode but am having issues getting it to work right. This circuit works fine and show Vout = 6.198V. However, if I swap their positions - Here, Vout = ...
37 views

What is the value of the node voltage, V1?

The value of the Vz (voltage across the Zener-diode) is 4V. There is also a current flowing against the diode. We know that when a diode is in the zener region, Vd = -Vz. I tried a simple KVL and got ...
97 views

Schottky Diodes as Full Bride Rectifier

I need to make a 75-100vdc high current power supply. I do not have any high current diodes or bridge rectifier ic’s but I do have a load of scrap switching power supplies. Could I take 4 of the(lack ...
30 views

Solving this mathematical prb on diode [on hold]

I am unable to solve this problem, help me.. please explain each steps briefly..
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Laser diode feeding DIY driver

I am interested in feeding a laser diode (LD) with 2.5V and 210 mA. I am using basically a Darlington configuration as shown in the schematics. In order to prevent any damage to the LD I am using a ...
75 views

Why don't we worry about reverse recovery voltage and current of a diode in a simple circuit application?

When the diode goes into reverse recovery, why don't we worry about the power supply in that specific time since the current will be increased? Will it not damage the power supply or is it since it is ...
2k views

Noise Model for Zener Diodes

I am trying to design a noise source using discrete transistors and a Zener diode in the avalanche breakdown region. Therefore, I have several questions relating to the use of the diode... How does ...
145 views

Why do we need a 2kOhm resistor

What is the purpose of the 2k resistor in the schematic below? I am guessing the current through the diode will be infinity if it were absent?
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Diodes- circuit

Hi! So I have this problem. I've read all the books I could and watched many youtube videos but I still cant understand how to find R in this circuit the only info I have is that V out=3. If someone ...
42 views

Need help on optoelectronic devices calculations [closed]

So, we have this homework which seems to be for Master or PhD degree, I am still an undergraduate. Please help me with this please. I am really having a hard time solving this.
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Forward and Reverse Bias regions for voltage versus current of diode

Below I have the graph of the voltage of a diode versus its current. As you can see, the forward bias region is when Vd>0 and reverse bias when Vd<0. My question is: In which region does Vd=0 fall ...
184 views

A Drone 1900w led lightning flasher with a ssr problem. Help please

I'm a lighting technician that works in the UK film industry. I was really hoping some one could help me with a SSR switching issue. I have built a led lightning flasher to simulate storm lightning ...
177 views

Step by step working of PN junction diode

In a PN junction diode, as far my understanding, when we apply a forward bias, the free electrons from n type material will cross the junction and then it will again recombine with the holes of p type ...
290 views

Is the following information about the diode reverse breakdown voltage correct?

Regarding the PN junction diode, is the following information correct?: How come the reverse breakdown voltage increases with temperature according to the above graph? Am I interpreting the plots ...
170 views

Non-linear amplification circuit

I've got a few questions about a task from my exam preparation paper. The sketch below shows the circuit in question. It is given that U_E varies between 0V...3V. The operating voltage U_B is 10V. The ...
234 views

LC circuit with series diode (finding the linear average)

I've the following series LC circuit: Find the (linear) average of the current trough the diode. The ideal is a ideal component. The initial conditions in the circuit are equal to zero. MY ...
197 views

How to replace an LED with a diode and stop LED after timer ends?

So I have been working on this circuit that basically will activate an LED when the lux levels drop low enough. The time that the LED will remain active for is determined by VR4. I'm having two issues ...
290 views

When doing calculations regarding diodes (in half wave rectifiers), is the peak value of the sinusoidal source used, or is the rms value used?

For example, in Vdc = 0.318Vs, is Vs the peak voltage, or the rms voltage. Likewise, how is the PIV determined, e.g. in part (e) of this question: 4.65 Consider the half-wave rectifier circuit of ...
57 views

Same diodes (BAT54) from two manufacturers with different LTSpice characteristics?

Leaving the package and the resulting thermal characteristics aside, do diodes with the same name from different manufacturers have the same characteristics? I would think they should, but when ...
58 views

How triac acts as a diode and two transistor?

I'm constantly reading this fact that a Triac acts as a diode and two transistor. Can someone explain it.
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Need the value for D12 on this Aerobics Inc. 501009 PaceMaster Digital P.S. Board

Need help on finding the value for D12.
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Transistors and Diodes maximum current per size

As you can understand my knowledge in electronics is limited. I am trying to find throughout the internet a way to find the maximum current I can put through a transistor or diode versus their size. ...
3k views

Why did they use ultrafast diodes in a 50 or 60 Hz bridge?

This is again from an HP power supply (PSU). The incoming 230 V is rectified into 340 VDC and is fed to a switched-mode supply. The odd thing here is that the manual for that unit, HP6023A, ...
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How To Run Shaving Machine Without Bettary? [duplicate]

I'm just an amateur in this and I Need Help.. I've drawn this circuit of my Shaving machine and I want to remove the battery and connect it directly to one of these phone chargers-: The first: ...
1k views

Can I make pulsing light using AC as source, a diode and a LED?

I'm new to this branch of physics hence my stupid question. I know that diodes are used to make current flow in only one way. If I connected an AC source to a diode and the diode to a small light ...
82 views

How can a resistor be given a positive and negative characteristic?

This question is not pertaining to a circuit, but to individual parts itself. If for any reason, i want to make a resistor have a positive and negative charge on its either ends, what would be the ...
106 views

What is the circuit formation in this electric blackbox?

It should be a simple question from my exercise book, but I could not find the solution for some reason. As illustrated, in an electric blackbox, there is one switch (k), one 3-volt battery, three 1-...
16k views

Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors

The Raspberry Pi B+ models have a protection circuit between the USB connector and the 5V net on the board. They recommend putting a similar protection circuity on a Pi HAT before 'backpowering' the ...
43 views

Using schottky diode near reverse breakdown region

I am currently using a 1N7070 schottky diode as the output rectifier for a flyback converter. The designed reverse blocking voltage is 70V. However, due to leakage elements I am seeing a transient ...
86 views

What is the voltage across the diodes D1 and D2?

Following is the circuit I have been analyzing. Voltage supply at the input is -6V. I have to calculate the voltage across the diodes (D1&D2) or R2. simulate this circuit – Schematic ...
327 views

Different combinations for ADC input protection for measurements

I want to measure 0 to 5V DC analog voltages by the ADC of a microcontroller. Lets call the input impedance of the uC as Rin. I want to protect the ADC from possible spikes or over voltage. But in ...
45 views

resistor placement for zener diode for over voltage protection

i have searched in over voltage protection (like mosfet ) , i wanted to use zener diode parallel so it wont dissipate power unless in over voltage protection , but its power is low so i read that i ...
33 views

flyback diode across the relay coil

so my question is regarding the diode used across the relay coil. My A level textbook (the section from the textbook is given below) says that its purpose is to protect the op-amp from a back emf ...
487 views

Adjusting the offset of the output of a UA741CN opamp

I've the following schematic for a UA741CN when there is NO offset: simulate this circuit – Schematic created using CircuitLab Question: Why do we need the diode and the two resistors to ...
309 views

confused about diode polarity vs circuit polarity

I know the anode has a + sign and cathode has negative sign. But are these signs reversed depending on how the diode is connected with the circuit? In the above pic, in fig 4.2b, why isnt the - sign ...
27 views

Successive Detection Logarithmic Amplifier

let's consider this logarithmic Amplifier: I do not understand why at the terminal LOG OUTPUT there is a current which is proportional to log(Vinput). The current flowing on each diode is equal ...
57 views

Do I need a protection diode to prevent reverse current flow into a voltage regulator?

I have a 78L series voltage regulator that is used when a power supply is connected. When the power supply is absent, battery power is used. The battery will skip over the voltage regulator. The ...
88 views

What are the bottom group of diodes for on BLDC motor control circuits?

I'm studying the control circuit for a BLDC motor and I can't figure out what function the diodes serve that I point to in the basic diagram. What are they for? At what point in the basic operation ...
24 views

Motor Control Reverse Current Diode

I'm having an intermittent issue with a motor control setup I'm working on. I'm using a Pololu G2 18v17 motor driver controlled simply with an Arduino. I have a current limiting resistor installed on ...
Let's say I am given the following circuit: along with $$dV_p/dT=0.139mV/K$$: Defining V1 the voltage above Diode D1 and V2 the voltage above diode D2 , we use the expression for the current of a ...