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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Using reverse conduction on board repair

I am sorry if the title is misleading. As I am not a native speaker, I really don't know what the correct words to be used in the title. If you know the right words, please tell me so I can update the ...
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2 answers
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Variable Forward Voltage Diode

I'm attempting to create a guitar pedal using diodes to clip the audio signal and create distortion. Specifically, I'm trying to create a circuit with variable clipping by using a circuit that acts ...
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Peak/envelope detector circuit for 30 MHz sine pulses with a 10 kHz PRF

My goal is to input 30MHz sine pulses, with a pulse width of 10us and gap of 90us between the pulses. The circuit should convert this pulse train to a TTL signal that goes from 0 to 5 volts. To ...
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3 votes
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Simple Diode Mixer Help

Edit: Thank you for your input @Kevin White, much better results with 100 ohm injection resistors, a 1K resistor for a DC pathway and a 1K bias resistor from Anode to +5V. I am an RF enthusiast that ...
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2 answers
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Why is capacitor discharge time higher when an LED is included?

I'm testing the discharge time of a capacitor. I found that the time is higher when an LED is present. Circuit with a capacitance of 100mF, 10k resistance and 5V voltage. By calculating discharge ...
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The problem with sensitivity time controlled (STC) based on pin diode

I'm using sensitivity time controlled (STC) pin diodes of PN:MPP 4201A-206 for our applications. Our operating frequency from 1300 MHz to 1400 MHz. See the schematic diagram below. As device ...
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68 views

Voltage drop protection [closed]

My circuit supplies 13V to a system, but one of the actions dropped that voltage to 9V. I need to implement a circuit that holds the initial voltage above 12V for at least 5 seconds. I thought about ...
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Where are the transistor number 18 and 21 in op amp 741 according to Wikipedia?

I was trying to implement this op amp from Wikipedia in Proteus : Like this: But I could not find Q number 18 and 21. What is the reason that there are not Q number 18 and 21? Or if this image is ...
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Why is the diode reverse biased in the determination of energy gap?

I know that the energy gap increases when we reverse bias the diode, but I still don't see why forward bias won't do the trick. How exactly does the width of the band gap matter in measuring it? A ...
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In this formula, where does T come from to the power of 3 divided by 2?

I read the tutorial that says Also, as T → 0, so do T^3/2 but i did not understand this argument. In this formula, where does T come from to the power of 3 divided ...
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2 answers
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DC-DC booster functionality

I am working on a DC-DC booster. I have already built it, boosting 1.7 V to almost 18 V. I am using an IRF540N as my transistor, an inductor, a diode, and two capacitors. I was reading about how the ...
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Help me to understand the output signal of this circuit

I want to understand the output voltage of this circuit. My analysis is: When we are in the positive half of the wave, the capacitor will charge and the current will flow through D1 after it goes to ...
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Ac voltage regulator to keep output voltage constant about 6v using diodes

I'm trying to design a circuit to keep the output voltage constant at 6 VDC for output load resistances between 0.5 to 3 kiloohm. It doesn't matter to have errors about 0.25 VDC on the output. My ...
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1 answer
60 views

Select zener for minimal thermal drift

The voltage of a Zener diode in the Zener breakdown region depends on temperature. Suppose we have 3 Zeners with the following specs: 3.3 V rated Zener voltage at 5 mA 5.1 V rated Zener voltage at 5 ...
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One freewheeling diode for two relays? [duplicate]

I have two separate relays, both with different part numbers and coil inductances. Both are driven with the same 12V 'control signal.' When the control signal is removed, the inductance of both coils ...
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MOSFET gate-source protection, in selecting a Zener diode, is there any consequence of the forward voltage / current rating?

In a design, I have Zener diode used for the protection of a MOSFET's gate and source as shown in the picture below. I'm comparing two diodes for this purpose, and most of the spec values are equal, ...
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Can the connection of collector and base in these circuits be considered as a diode connected transistor?

I was learning how to design an op amp and I saw something thatis called "diode connected transistor." Like this image: Later I saw a person that was teaching about these circuits, and he ...
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7 votes
2 answers
180 views

Is there an analytic expression for the avalanche and Zener diode VI curves?

Ordinary diodes obey the Shockley diode equation, but I can't find anything similar for avalanche and Zener diodes. It's easy to find their VI curves, crude piecewise fits and lots of descriptions of ...
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Flyback diode over BTS7960 motor driver

I am using a BTS7960 24V DC motor driver to drive my 24VDC motor in combination with a microcontroller (PIC16F18875) with a PWM output of 13kHz. It works (almost) fine. When i tell te motor to stop (...
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If there are multiple holes and one electron wants to release then how can i know which hole will trap that electron? [closed]

I saw a tutorial about concept of holes that says : This trap and release is slower than the moving of electrons on its own. According to that image there is just one hole that replaces its position ...
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How can KCL be satisfied here?

In the transistor biasing using diode below assume that at time t1 the circuit is stable and apply KCL at the junction of the three devices you have: ...
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5 answers
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Can I use a normal diode as a Zener/Varistor ? If not, why not? (focus on Varistor use)

When I look at a normal diode graph like that I see the Vz Zener voltage of it looks just like a Zener, so why not using it reverse biased like a Zener? I ask like that because I never saw it being ...
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2 votes
1 answer
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How to analyse non-linear circuits

There is a universal method for determining voltages and currents in a linear circuit - that is, a circuit containing resistors, inductors, capacitors and op-amps. Laplace transfrom the input source, ...
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In this image where is the base of Q3 connected to?

In this image the base of Q3 shows an arrow that points to the 10k resistor, but I do not know where is it connected to. Image: According to that image I do not know what should I do with the base of ...
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Zener diode Zener breakdown modelling

The IV curve of a Zener diode inside the Zener breakdown region looks like the IV curve of its forward bias operation. Is there a formula which can give the IV relationship in the Zener breakdown? The ...
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1 answer
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Diode SPICE data accuracy at high frequencies?

I'm trying to do a non-linear harmonic balance simulation on a schottky diode model MACOM MA4E1317 that according to the manufacturer is usable up to 80 GHz. I got the SPICE data and S-Parameter files ...
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4 votes
4 answers
606 views

0 current in a circuit using tunnel diode

Suppose we have a diode with negative differential resistance of -40 ohm in the region of 0.3-0.5 V and we put it in parallel with a 40 ohm resistor: simulate this circuit – Schematic created ...
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8 votes
2 answers
559 views

What is the purpose of the capacitor and diode in this fan driver circuit?

I have an FPGA dev board with a fan PWM circuit so that you can hook it up to a fan + heatsink. I happen to like this as we put a common heatsink together for the hottest components, and I drive it ...
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1 answer
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Odd results from mesh current analysis in a circuit with a diode

I have this circuit: simulate this circuit – Schematic created using CircuitLab The reverse saturation current of the diode is 10^-6 A. I use mesh current analysis to find the current inside ...
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4 votes
2 answers
759 views

What's the purpose of the Zener diodes in this boost circuit?

I am looking at this boost converter for stepping up voltage to charge a Li-ion battery: It looks like a standard boost topology, but I am new to this and am wondering: What is the purpose of the ...
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2 votes
1 answer
170 views

Why aren't smoothing capacitors used in smoothing the output of fully controlled bridge rectifiers?

I was wondering why smoothing capacitors are not used in smoothing the output of fully controlled bridge rectifiers, like it is used in the uncontrolled bridge rectifiers.
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Switch and diodes

I have this schematic with pic18f47k40. In this project I have 6 switches, a pic18f47k40 microcontroller and dfplayer to play music. I want that when I press a switch, the microcontroller tells ...
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Non-rechargeable 9V battery with diode between 12V car battery

I have a microcontroller which is powered by a car battery, voltage is stepped down to 3.3V using a voltage regulator. However if someone cuts the cord to the car battery the microcontroller has a ...
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2 votes
4 answers
483 views

What happens when we increase the voltage beyond breakdown in a Zener diode?

In the presence of a resistor, we can reason that the voltage difference between the given battery voltage and breakdown will be given to resistor. My question is without any other devices just only a ...
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2 votes
1 answer
70 views

Measuring the diode current

R1=15kΩ R2=40kΩ R3=40kΩ E=4V VI--> -8V<VI<8V. In this circuit, diodes D1 and D2 are the same model 1N4007 diodes. (Is=7.02767E-09, VJ=0.7) When I assume that D1 is on and D2 diode is off, ...
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Shouldn’t the Zener diode be not in active state here?

I thought the Zener diode (break down voltage = 6V) will not be active here. That is it will not start acting as voltage regulator here since potential difference across 4 kΩ is 4 V if not in ...
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1 answer
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Confused about back EMF protection in maglock circuit

Straight upfront...electrical engineering is not my forte. However, I am trying to help a client with a particular issue and I'm hoping this community can provide some invaluable insight. They have a ...
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4 votes
3 answers
331 views

Voltage Based Current Limiting Application

I have a mobile application where I need to pre-charge the capacitors in a Victron 24v MultiPlus with a resistor before closing the circuit switch to its battery bank (24V 200Ah lithium); this ...
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-2 votes
1 answer
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How can I figure out Vout as a function of Vin?

I am not sure how to solve for when the diodes will be in what mode. Any help is appreciated :).
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3 votes
1 answer
81 views

Noise of a precision/active rectifier

I am trying to build a precision rectifier circuit to implement AM demodulation in a sensor signal chain. For now I have calculated the sum RMS noise of the total signal chain except that of the ...
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3 answers
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Application of superposition theorem in solving the voltages of the diodes

Why do we need to apply superposition in this problem to determine the V0 instead of assuming that only Si diode will turn "on" since it has a lower knee voltage compared to the GaAs diode? ...
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2 answers
62 views

Schottky Diode configuration

I'm studying some schematics about Google Coral Dev Board, and I have found this: Where VBUS_1 comes from USB-C OTG connector and VBUS_VIN comes from USB-C Power only connector. What is the resistors ...
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2 votes
3 answers
69 views

What does the VCC pin do in this Optocoupler?

I have this optocoupler, and I am trying to figure out how it works. What is the VCC pin supposed to do? How does it supply current to the gate pin of the transistor? https://www.digikey.com/en/...
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1 answer
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Help needed in understanding the lab observation regarding a diode

I was trying to understand the connections in a power supply board. It was found that anode of below diode is connected to GND and -ve terminal of bulk capacitor. Cathode of diode is connected to +ve ...
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Working of this Circuit - Reset

I'm using this Ethernet transceiver PHY to study the working of the RGMII interface. Can someone explain the working of figure 18 on page 75? What is the purpose of D1 and D2 along with the RC? How ...
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Inconsistent diode and MOSFET power rating

I’m trying to design a power supply for an electromagnet. For this, I’m using a Buck topologie in which the electromagnet is the coil. The voltage comes from a 400V PFC. Required current is 8 Amps (...
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Diode and resistor in parallel

I was recently investigating a model of a circuit in which there is a resistor in parallel with a forward-biased diode. Why is the current passing through the resistor dictated solely by the forward ...
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1 answer
41 views

Flyback diode rating questions

I'm currently working on a magnetic levitation project which revolves around levitating an object below an electromagnet. This was inspired by a magnetic levitation project that I found online. The ...
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2 answers
31 views

Surge/signal protection for low voltage ECG leads

ECG leads generally see voltages in the range of -5mV to 5mV and a frequency range of .05Hz - 150Hz. We are peripherally stimulating the patients with up to 200v at a frequency of 1kHz elsewhere on ...
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1 vote
2 answers
70 views

Why does reverse recovery behavior matter for half bridge bootstrap diode?

I have seen several recommendations in the past to use a schottky bootstrap diode in half bridge drivers, even if the driver integrates a Si junction diode for the purpose, because supposedly the ...
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