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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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79 views

Thevenins theorem + two diodes and a resistor using graphical solution

I've got a homework to solve this circuit by a thevenin's theorem and get a current and tension of the diodes using graph. I've looked all around the Internet and couldn't find one single video that ...
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7answers
135 views

Calculating the voltage drop of two Zener diodes in series? (reverse conducting)

I'm building a circuit powered from a 12V 55mAh (A23 battery). Needless to say that power consumption is a primary concern. The circuit is an ATtiny85 which is driving 13 LED's (in 5 groups). I ...
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0answers
19 views

Issues with calculating the minimum value of the Load Resistance (RL) in this scenario

I am currently in Year 12. I am facing issues with calculating the minimum value of RL before regulation stops in the following circuit: Below are the questions associated with this scenario: ...
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2answers
80 views

Very basic diode question

I was just thinking about diodes recently and I came across this video https://youtu.be/bXEyCf1P0UU?t=35 Minute 0:32 He says the power disspitated by the diode will be the forward voltage drop Vf (0....
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1answer
129 views

TVS bidirectional diode not working

10x bidirectional diodes 1.5KE400CA in series, balanced, then the chain in parallel for DC line protection. Breakdown voltage 400V per diode. Still got 10kV+ voltage spikes (picture below, x100000 ...
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3answers
50 views

Reverse Diode and Resistor in parallel for battery connection. What do they do?

Can you please help me understand what the diode and resistor connected to the battery input line of this circuit are doing? Thank you!
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0answers
13 views

1 motor 2 power suplies to control direction

Well it has been a long time since I have played with motors and electronics, and I hoping to get some direction for people much smarter than I. I have a 12Vdc actuator I use to control a door. I ...
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1answer
60 views

Power issue on connecting controller to FTDI programmer

Hi, I have connected my controller (ATMEGA2560) input to 5V power supply. At the VCC terminal 5V is shown. The VCC, TX,RX, RESET and GND pins are connected to a FTDI programmer port as shown in figure....
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2answers
39 views

Voltage of opened diode

We have an opto-isolator diode connected to a contact closure to ground. When the contact is closed, the cathode reads 0V when measured to ground. When the contact is opened, will I measure a voltage ...
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1answer
74 views

Why does my power diode have 4 terminals?

I am using a high voltage diode (APTDF400U120G) to freewheel an inductor in a switching circuit. It has four terminals, two for either side of the diode. I cannot figure out why this is. If I only ...
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0answers
32 views

Solving a RLC circuit with a charged L and C

I've the following circuit: The input current is given by (the pules endures \$1/20\$ seconds and starts at \$t=0\$): $$\text{I}_{\space\text{in}}\left(t\right)=\max\left\{\mathcal{L}_\text{s}^{-1}\...
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1answer
63 views

How to find voltage on zener diode while there is a current source

simulate this circuit – Schematic created using CircuitLab I'm confused about whether zener is on or off due to not being able to know voltage on V0. I tried to find by applying KCL & KVL, ...
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0answers
46 views

Can a rechargeable NiMH battery be replaced by a non rechargeable battery

I am looking to change a Toshiba laptop rtc battery as the current one is no longer working. The current battery is a 2.4V 40 mAh NiMH connected to the laptop via a 3 pin connector with only 2 wires, ...
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0answers
19 views

Repair/Reuse Hitec servo PCB

I have a question; I have a servo (a Hitec MG625) which did accidentally have current going the wrong way through it due to a mis-configured "servo wire" - I can identify which component on the PCB ...
2
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0answers
33 views

Factors affecting the \$V_f\$ of a Schottky diode

The usual wisdom about Schottky diodes is that their \$V_f\$ is around 0.2 to 0.3 volts, but what specifically determines this? I know that for p-n diodes, doping concentration can affect the forward ...
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5answers
75 views

Does a transistor work by connecting the collector to emitter? If so, why do transistor regulators work?

I am wondering why a transistor, such as one used in this Zener diode + Transistor regulator , has the output controlled by the base voltage rather than the collector. My textbook (which has this ...
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1answer
24 views

TVS diode with 10 - 15 V forward voltage

I came across this TVS diode: https://m.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smf3_3_datasheet.pdf.pdf It has a forward voltage drop of 10 to 15 V. Why? How? ...
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1answer
43 views

Diode Substitution

I am creating a printed circuit board that is utilizing a circuit from a sparkfun product: (https://www.digikey.ca/product-detail/en/sparkfun-electronics/SEN-12642/1568-1290-ND/5762440) I have ...
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2answers
383 views

Cathode Interpretation Contradiction [duplicate]

When I learned, what the anode and the cathode are, there were two definitions corresponding to each other: Cathode is, where electrons enter in the system. Anode comes from the greek anodos meaning "...
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1answer
123 views

when a diode is forwards biased can current flow backwards through it?

when a diode is forwards biased can current flow backwards through it? this question comes from me trying to understand class AB amplifier biasing, so any additional comments about the diodes' use ...
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3answers
118 views

Why are the diodes in this circuit forward biased in spite of no current flowing through them?

Considering the following circuit, Normally in the +ve half cycle SCR1 is triggered after it takes its triggering gate pulse and then D2 becomes intrinsically forward biased so it's on and conducting ...
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0answers
55 views

Solving a circuit with a diode in it

I've got the following circuit: The diode lets current flow in one direction, so when I write down the transfer fuction (the input current divided by the input voltage) it get: $$\frac{\text{i}_{\...
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1answer
29 views

Which replacement Zener Diode should I use?

I am repairing a television power supply and have found a couple Zener Diodes that are bad. The service manual gives only a part number of VZMTZJ30DT. I have searched online for hours and cannot find ...
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2answers
1k views

What role does this diode play?

I've just bought an Arduino Uno kit, and am going through all the projects in the booklet that comes with the kit. From even the simplest LED and resistor circuit, to get a feel for the Arduino board, ...
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0answers
180 views

How do you calculate RC snubber values for a discrete bridge rectifier

I'm working on a small linear power supply for an audio amplifier (home/hobby use) and I want to add an RC snubber on the rectifier diodes. I know this might be overkill, but I'm looking at it as an ...
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1answer
46 views

Check for 12V with Arduino (Two resistors and a diode)

I need to read the presence of 12V on one of the lines of the board. I want to read using Arduino UNO. I found the following scheme: Is this scheme correct?
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2answers
46 views

DC motor on rectified AC voltage

I recently built a 12 V AC rectifier to DC using a 220 V/12 V transformer. I just connected a diode bridge and a capacitor in parallel to give the DC output. But when I connected a 12 V DC motor(...
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1answer
40 views

High side driver internal design

I have a question about the high side driver VN7016AJ for automotive applications, during ISO pulse1 -150 V will be applied at its VCC pin, I found from the User manual (UM1922) that when -150 V is ...
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3answers
81 views

A question about reverse polarity protection diode

Is the function of 1N4001 before the 5V regulator reverse polarity protection? Is this a fine method? And I sometimes see 1N4148. Can any diode(besides zener) be used for such function?
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1answer
46 views

What will happen if P-channel Enhancement type MOSFET gate kept open while connected as diode in real case

[ I am using MOSFET as diode for polarity protection of system. Vehicle supply of 12V is applied to drain & system is connected to source. Gate kept open purpose. I have simulated attached ...
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0answers
94 views

Capacitor in series with diode

Hi, not sure if I'm getting this right. Current flows from the positive side of the AC voltage supply and charges up the capacitor, the capacitor cannot discharge as the diode is reverse biased. So ...
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0answers
18 views

Polysilicon Emitter equivalent for PNP BJT

I recently read (in the book semiconductor device fundamentals by Pierre about polysilicon emitter technique used in a n-p-n Bipolar Junction Transistor (BJT) to enchance the current gain of BJT. I ...
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0answers
54 views

Ideal diode IV characteristics

If I know that the Ideal Diode only allows current to flow once V > 0, how would I go about implementing the two resistors into the IV graph? How do I analyse the circuit as a whole IV graph?
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4answers
100 views

Transistor driving LED

I have already asked a question regarding this problem but it was about a different thing, slightly. Here is the drawing of a LED driving circuit. The problem I have encountered with traditional ...
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3answers
91 views

How to isolate several voltage sources that feed a single voltage meter

I need a way to isolate several voltage sources around a large vehicle that feed a single voltage meter some distance away on a panel. Each source is selected by a momentary-spst (at the source). ...
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0answers
21 views

Rectifier Design RL load

I have a design problem with the circuit below, in order get the commutation angle u I need a value of Ls, assuming all other values are known in the formula below. As far as I know, Ls & u are ...
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1answer
25 views

How to add the TVS protection?

I'm still busy with my DMX splitter (soldered everything), however, I made a mistake with my TVS protection diode. I put it in series with 220 V AC, and nothing happens (no current flows). I expect I ...
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1answer
73 views

Explanation for circuit with 2-stage op-amp, with diode in between first output and second input

I am a beginner in op-amp design and would like to get an explanation to a circuit that has a diode wired in between the output of op-amp-1 (stage 1) and the input of op-amp-2 (stage 2). The ...
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2answers
75 views

DIODE: why is it that as current --> infinity ( gets really large) the following happen:

In a forward bias Diode, why is it that when current gets really large : 1) voltage drop across the diode does not increase a lot ( its because of logarithmic nature? and if so why is it logarithmic)...
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2answers
48 views

Diode package selection in flyback circuit for a relay

I intend to use the following flyback circuit for my relays (third circuit circled in red): Here are my relay specs: 1) G6DN - 5 A 250 VAC contact rating Coil voltage = 5VDC Coil resistance = 227 ...
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0answers
23 views

GSM868 UART interface

I have doubt regarding the diode direction.How the UART communication will happen between DTE TX ---> GSM RX? Kindly explain.
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1answer
1k views

Logic behind this fuse status indicator

I was doing this circuit which I found on the Internet. My question is what is the logic behind the functioning of this circuit? Thanks!
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1answer
96 views

Should I Use a diode for this application? [closed]

I am trying to run a small 12v motor from the same battery. One source is a timer the other a remote. The timer does not function when both are hooked up to the motor. I’m assuming it is from feedback....
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1answer
63 views

Two source diode protection [closed]

I need to protect the 12.8v regulator from the 14.5v battery. Do I try to just reduce the battery voltage below 21.8V with a bunch of diodes? Do I just put one diode protecting against current flow ...
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0answers
29 views

SMD diode with marking code 6 (or 9)?

What's the model (or type) of the diode below? The mark maybe "6" or "9". The size is about the same with the SMD 0603 resistor. They sit at the output of one amplifier.
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1answer
30 views

Confusion about output voltage

While solving these problems I'm confused about sign conventions of output voltages of IDEAL Diodes. Actually I can't get between which nodes the V is to be taken? Is it between +5 and -V? I solve ...
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2answers
86 views

How to solve a a full wave rectifier with two diodes and a ground in the middle?

This is the problem I am trying to follow along with the solution but I don't understand what is happening, how do I handle the random ground in the middle?? is the node between d1 and d2 40Vpeek and ...
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3answers
91 views

Finding necessary voltage for diode conduction

simulate this circuit – Schematic created using CircuitLab In the following, I need to find \$V_a(v_{in})\$ such that \$D_3\$ is on. Assume a forward voltage drop of \$0.7V\$. From past ...
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1answer
32 views

Identity and advice on replacement of SM diode

I have a Sonos Play:3, which is past its warranty. I dismantled it to find it has the well documented fault with a blown capacitor. However, there is also damage also to one of the surface mount ...
1
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1answer
83 views

MOSFET - shorting the gate and source

I am currently in the fourth year of my bachelor's degree and my knowledge on this is really really really very limited, but i got a simulation circuit of an isolated dc-dc converter from my senior ...