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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IC current problem [duplicate]
From the source (controller) I made a serie with a diode (to adjust the V) and the IC (L298) input (an and gate);
It works but the current extreamly higer than its supposed to be.
Why ? Can it be the ...
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0answers
18 views
Bimetallic temperature switch not turning off circuit
I recently bought a bimetallic temperature switch (linked to amazon here). It's for an engineering project for school where we're supposed to use diodes and a temp switch connected to a DC power ...
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3answers
97 views
Diode power consumption
I need to convert from 4 to 3.3V. So I was thinking of a diode, or voltage regulator. Voltage regulators, I know that it uses about 5mA to do the job.
How much current a diode uses ? I cant find this ...
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0answers
35 views
Diodes when voltage is applied
Does the hole injection take place from p semiconductor to n semiconductor in a pn junction diode? Or it takes place only in the case of a transistor?
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1answer
52 views
How these two diodes used in the ciruit protect from the voltage spikes?
I'm playing around with a simple DIY project, and after about three days of googling and reading stuff I still can't wrap my brain around two Schottkys below:
From the project page:
The two ...
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1answer
29 views
About curent on the diode
What is the internal structure difference between diode can take current and another one can take more current than the first one?
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0answers
16 views
Neutrality when diode is given an voltage
When a diode is forward biased, the majority carrier electrons move in to p region from n region, now my question is how does the neutrality exists when mobile electrons entered the acceptor ...
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0answers
29 views
Combining the output of two ignition coils? [on hold]
I'm considering trying to use two ignition coils to feed to a single distributor on a traditional older V8 engine. The coils would be controlled via a microprocessor to allow them to fire alternately, ...
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1answer
52 views
LED behavior during 24 VAC negative half cycle
I don't understand why the green portion of LED3 is able to conduct. Since the path marked in green represents the negative half-cycle of the 24VAC isn't the green LED reverse biased therefore no ...
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2answers
114 views
What is the purpose of a diode and resistor at the gate of a FET in this LED driver circuit?
I am trying to design a LED driver based the LM3409HV IC.
I am using the reference design from TI as a starting point.
The schematic in the datasheet has a diode (D2) and a resistor (R5) at the gate ...
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1answer
44 views
How can I change the circuit or the current to effectively heat up the diodes based on their current rating?
I'm extremely new to electrical engineering, and I was experimenting with diodes in series. I soldered six 1N4007 diodes together, and I connected them to a DC power supply (RSR ET122) with a constant ...
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4answers
91 views
1N5822 schottky diode heatsinking
Is the cathode for schottky diode hotter than the anode, as is common for most diodes, or is it reverse polarity? A schottky is a metal-semiconductor junction, with the metal at the anode. So it ...
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1answer
55 views
Protection diodes
What are the rules when placing protection diodes into a power supply schematic?
More exactly, I have the attached schematic and I placed the protection diodes (D2, D3, D4 all of them 1N4007). Those ...
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1answer
27 views
Thermal drift in diodes
Hi guys and thanks for reading and your help. I can't understand a thing that my book says: "When the temperature grows, the diode will let flow more current" and then it gives 2 formulas:
\$V_t = \...
3
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1answer
51 views
Drift current in PN Junction
Ok guys, first of all thanks for your support and your help, I can't understand how the drift current work, let's say that we have this junction
By the definition of the drift current we can ...
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2answers
32 views
TVS diode Clamping voltage
How to choose TVS diode?
What's clamping voltage?
If in case TVS diodes clamping voltage 57V if anything more than 57V what will happen to diode and circuit?
Would it break? Or pass the voltage?
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0answers
39 views
Can this smarphone works without a protection diode? [closed]
While I was replacing the battery, I detached a component with my fingernail. Which component is it?
Image:
Device name: Xiaomi Redmi5 plus
You can see the missing component in the small orange ...
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2answers
35 views
Is my solution to prevent leakage between power rails correct?
I have two boards with identical comparator circuitry (shown below). I want to detect in each board when the other is plugged in. My concern (in the picture) is that when I connect the two boards if ...
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1answer
27 views
Diode reverse current
If I apply an current source into the the cathode of a diode (current flow into cathode), what can possibly happen to the diode.
For the cuicuit below, when the FET is OFF, how does the battery ...
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4answers
3k views
Why does an LED have to be a diode?
I know LED stands for Light Emitting Diode; but why does this component need to be a diode to emit light?
My question assumes that the "leds" we see everywhere (for lighting, screens, etc) are ...
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0answers
21 views
LTC3780 for charging batteries (backflow protection)
I have very little experience with these type of things and I couldn't find the answer anywhere else. I want to use LTC3780 module with ATX PSU to primarily charge batteries (deep cycle battery and ...
0
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1answer
77 views
Why do bidirectional (TVS) diodes sometimes have a 'direction' mark?
TVS diode with marker
Some components that are needed to be be in a certain direction (like most diodes, and some capacitors) there is a white line over the component to show the direction.
But why ...
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0answers
20 views
Reverse Recovery of Diode
I'm simulating the below circuit to check the recovery characteristics of a diode.
I connected the diode's cathode to a voltage source which will go from 0V to 200V after 50us. I found that the ...
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1answer
102 views
Using a zener diode and a bjt to regulate voltage received by a controller
Okay, here goes…
I’m trying to create a circuit that will prevent low conductance (from rain water exposure) which occasionally shorts a particular switch, from triggering a controller input that the ...
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3answers
115 views
Can I use 1N4148 diodes instead of a 1N4001 diode for reducing the speed of a 5V 1.8W fan?
Looking at this 1N4148 datasheet, it seems that the forward continuous current is 0.3A, thus 300 mA. So if I add two in series, I will get 600 mA.
I want to use diodes to reduce a 5V 1.8W fan speed. ...
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1answer
33 views
PIN diode in RF switching vs. PIN diode used as photodiode
From what I understand, there are traditional photodiode components that are designed with PIN diodes, in which the gate is activated by light saturation. For a PIN diode component made for RF ...
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2answers
438 views
Full wave rectifier with a high DC offset voltage?
For a full wave rectifier, can it rectify an AC wave with a DC offset above the rated voltage of its diodes rated voltage if the peak to peak voltage of the wave is within its rated voltage? Like if ...
4
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2answers
408 views
How can I compare a TVS diode with a varistor?
For a 120Vac line protection element, comparing this TVS diode:
With this varistor:
The immediate differences I see are:
The varistor is marginally cheaper
The varistor specifies a maximum working ...
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2answers
77 views
Laser Diode Feeding
Edit: Laser diode info page
I have a basic question about laser diodes. For a 14-pin butterfly package as shown below. I know that I need to control the current going in to the laser diode, but I don'...
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2answers
101 views
flyback spike elimination
I have a circuit that is switching a transformer primary winding from 15 volts to ground, through an N-channel MOSFET at 50 kHz. I was seeing occasional field failures and found that every time the ...
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2answers
993 views
Circuit to Breadboard [duplicate]
I'm currently working on a project which requires me to test the functionality of TTL logic gates by making use of diodes and resistors. To do so I must first place them on the breadboard and then ...
3
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1answer
46 views
Insulation of SiC Diode
I am reading about creepage distance and clearance and came across a T0-247-3 SiC diode (IDW20G120C5B). This diode is rated for 1.2kV which would mean that it won't break down at let's say 800V, which ...
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1answer
63 views
parallel configuration of diode [duplicate]
I want to connect diodes in parallel to increase the current carrying capacity. If I connect two diodes in parallel having same rating(same forward voltage drop), does thermal runaway still come in ...
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0answers
41 views
Current-Voltage relationship in diode
In a forward biased diode, with negligible reverse saturation current, how much does the voltage change with respect to the current through the diode?
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1answer
115 views
Choose correct forward current of diode [closed]
I've simulated the diode in LTspice and the result indicates two current peaks in the diode, the higher one(5.4A) only lasts 60us in the very beginning and the lower one(1.8A) lasts 3ms.
My question ...
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2answers
85 views
Why can't a combination of two diodes connected back to back act like transistor? [duplicate]
I saw an explanation of the transistor working here by Bill Beaty. I absolutely loved it. But I'm not entirely sure why the action cannot be achieved by two diodes connected back to back by a metal ...
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1answer
65 views
The forward voltage Vf of a diode
I want to know about the forward voltage \$V_{f}\$ parameter of a diode device, given an I-V charateristic curve and in ambient temperature. What is the criteria to define the \$V_{f}\$ for any diode? ...
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1answer
31 views
Why do we need a minimum voltage here?
Let's assume we have a circuit like this: (Us should be monopolar but I didn't find something like that).
simulate this circuit – Schematic created using CircuitLab
Negative half wave: D2 is ...
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2answers
60 views
Diode Array for Full-Wave Rectifier for PoE
I was looking for SCHOTTKY diode for designing Full-Wave Rectifier for PoE. I was searching for the diode but came across the ...
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0answers
18 views
Why does the minority carrier concentration increase exponentially towards the junctions in a forward biased power diode? (graph included)
[Image Source: Power Electronics - Converters Applications and Design by Ned Mohan]
Let's take the p+ side. Since the anode is of a higher potential (forward bias), shouldn't the electrons (minority) ...
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1answer
24 views
How deep does the depletion region in power diode penetrate the lightly doped n- layer under no bias?
I could find references for describing the depletion layer in a power diode under reverse bias and the consequent classification of Non-punch through and Punch-through diodes. But I couldn't find a ...
11
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1answer
541 views
Why do power diodes have a p+ n- n+ construction and why not p+ p- n+?
I've been learning about power diodes and how they differ from low power diodes with the addition of a lightly doped n-type layer.
This n-type layer improves the breakdown voltage rating of the ...
0
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1answer
50 views
Help understanding this schematic : Why is the diode there (AT89C2051 Programmer)?
I am having trouble understanding the following portion of schematic from AT89C2051 programmer circuit. Please help me comprehend what is going on here.
Here is what I understand:
A1 directly ...
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0answers
43 views
How to use an opto-isolator in my circuit?
I am very new to electrical isolation, and I have to build an electrooculogram circuit in which I use an optical isolation system (with diodes) to provide protection to the user. I have only found ...
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1answer
43 views
MagJack for PoE Powered Device
I am adding Power over Ethernet functionality in my Toradex's System-on-module (Colibri iMX6ULL) based carrier-board design. I ...
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1answer
97 views
Question about AND gate using diodes
Consider the circuit below:
I'm assuming ideal diode model(\$V_{ON} = 0V\$). If \$V\$, \$A\$ and \$B\$ are all 5V, the diodes will be reversed biased and no current will flow through the circuit. ...
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3answers
91 views
I need help understanding constant voltage model for diode
So I'm confused about the constant voltage model (which assumes diode has .7 volt drop).
In the pic below, I'm confused about the third case. What if the voltage source has voltage less than .7 V ...
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1answer
41 views
diode current ratings
I am looking a replacement of this diode BAV99W Datasheet.I have a confusion about Average Rectified Forward Current,Forward Rectified Output current and Forward Continuous Current ratings.What is a ...
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0answers
41 views
Draw the waveform of the clipping circut?
Below is what I got as my answer to the output wave form, did I miss something?
Also what is time average value mean?
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1answer
118 views
What is Maximum Average Forward Rectified Current? (1N4001 Diode)
I am wondering if someone can explain what Maximum Average Forward Rectified Current means for a diode. I see that this is marked as 1 Amp in the datasheet for the 1N4001. I have not been able to find ...
