Questions tagged [flyback]

A flyback diode is a diode used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply voltage is suddenly reduced or removed. A flyback transformer, also called a line output transformer, is a special type of electrical transformer designed to generate high voltage sawtooth signals at a relatively high frequency.

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Sparking when touching terminal on valve

In an effort to protect my relay I have added a diode for flyback protection. However when I touch the second terminal with power from the circuit I see a small spark. The source voltage is 12 volts, ...
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Why does slow-decay mode increase torque of brushed DC motor under PWM?

I am working on a project requiring high torque operation of a brushed 12V DC motor at low speed, plus software speed control from a microcontroller. PWM is the obvious choice here. My driver supports ...
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Why does a flyback converter in DCM mode have a different oscillation waveform at start and end of MOSFET turn off?

As seen from the waveform, when the MOSFET turns off, it has some high-frequency oscillations (shown in red) whereas before MOSFET turns on it has low-frequency oscillations. I have found that the ...
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Flyback: opto/Zener feedback circuit

Could someone explain the difference between these two flyback feedback circuits, and how the second circuit works? Any application note available would be a favor for me.
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Flyback Cross-Regulation

The document "Under the Hood of Flyback SMPS Designs", talks about the cross-regulation (on page 8). I have some questions about that. 1.) In what condition the primary voltage will ...
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Flyback leakage inductance effect

The document "Under the Hood of Flyback SMPS Designs", talks about the leakage inductance effect (on page 6). I have some questions about that. The below questions are from fig 5. Why high ...
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Flyback CCM right-half-plane-zero and control question

The document Under the Hood of Flyback SMPS Designs, talks about the RHPZ effect. I have some questions about that. 1.) Why do we need to design in the low input voltage and maximum current? 2.) I don'...
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Flyback converter DCM and CCM transition voltage

I am reading about flyback converter design and it is often said that the flyback converter should operate either in DCM or CCM. However, I understand that flyback converters can operate in CCM at low ...
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555 flyback - question about efficiency

How can I improve this scheme to reduce consumption? MOSFET is 4N0403
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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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555 FlyBack low power

I want to build a 555 converter with which to get 3 V AC ~ 100 mA, I stopped at the diagram below. I need help to increase the efficiency of the circuit. Load is VFD display (for filament drive), so I ...
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Low side driver and flyback diode

I wanted to control electric door lock (12V, 1.5A peak, unlocking time < 200ms) with Self-Protected Low Side Driver like NCV8412 (https://hr.mouser.com/datasheet/2/308/1/NCV8412_D-2317556.pdf). One ...
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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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Is it Possible to use an MOV instead of a Flyback Diode on Pulse Cicruit

I am working on a small high voltage pulse circuit to protect my animals and I have a question about the flyback diode D2 to protect the SCR The flyback diode seems to waste a lot of energy between ...
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Two-ground issue

I've been working on a project which I need to rectify, filter and later lower the input filtered voltage (311V) to 12V, as shown in the picture making use of a flyback converter. The problem arises ...
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In multi-o/p isolated converters, would the gating pulses be same for all the outputs and cross regulation happens through transformer turns ratio?

I need to generate 2 outputs , 12V (Output1) and 28V( Output2) from a single isolated flyback converter ( multi- winding). If Iam going for synchronous rectification ( MOSFET is used instead of diode)...
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Flyback converter input current

I have solved A and B of this question but i have no idea how to solve C. any help would be apriciated
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Voltage waveform of flyback transformer

I am doing the hardware implementation of the flyback transformer as per the attached figure, but I am not getting the proper voltage waveform at Vs and Vd. The frequency is 20 kHz, the turns ratio is ...
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Flyback transformer simulation

When I'm using a BJT for switching the flyback transformer, I"m getting the desired current waveform across the primary, but when I'm using a MOSFET, I'm getting a pulse signal as the current ...
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5 votes
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Selecting a flyback diode

According to the schematic below , where J15 connects to solenoid B11HD-255-B-3 and solenoid B11HD-255-B-3 is rated 19V, 90W, what is the technical approach to selecting a flyback diode? (D15) I have ...
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A forward converter or flyback converter without voltage spikes?

I was thinking of a way to avoid voltage spikes in a flyback converter and I decided to redirect voltage spikes back to the battery, hence dampening the voltage spikes. Will this method work ...
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What is the meaning of below notations in flyback/forward transformer datasheets?

Flyback / Forward transformer datasheet How can I decipher the above diagrams? Does the inductance value represent magnetizing inductance? Why are there 2 windings (1-3 and 2-4) at primary side of ...
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Why is buck-boost converter showing a different trend than buck and boost in efficiency peaking point?

In general I was under the impression, the efficiency is highest when input and output voltage are close to each other. This holds good for boost (text book image below) and buck (personal experience)....
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3 votes
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How do we appropriately select the duty cycle in a flyback converter?

In a flyback converter, we have the freedom to choose appropriate duty cycle by adjusting the turn ratio to meet the desired output voltage. The link says Developers will need to know several key ...
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Simulation in Proteus

I want to simulate a flyback transformer in Proteus. But in the Proteus library a transformer with opposite dot convention is not available. So, how to get a transformer of opposite dot convention in ...
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Is a balancing diode really necessary for the Balanced Boost converter?

Please pardon all of the information that precedes the question -- I didn't want you to actually have to go read the paper itself. This question is in two parts, but they are really equivalent, so it'...
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Flyback primary side control

I read the LT3573's datasheet, I have some questions would like to ask. Based on this block diagram, 1.) What's the main function of the below circuit (red circle). 2.) If I need to detect the output ...
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Strange Isense shape for my flyback

I have strange shape when I'm measuring Rsense voltage, before that circuit, I have already made a flyback conerter with this SMPS transformer https://docs.rs-online.com/696a/0900766b80107114.pdf and ...
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What is the min and max input voltage range of a buck converter to maintain efficiency above 90% [closed]

I want to design a stepdown converter from 72V lithium ion battery to 12V, 5A. I am torn between using a flyback converter and a buck converter. Which topology will give me maximum efficiency at that ...
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Rogue winding on flyback transformer?

I was reverse engineering a battery charger (Lidl brand Parkside 20V battery charger PLGS 2012 A1, with smart functions, among them charge current and termination voltage settings) and came across ...
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Flyback transformer simulation in Lt Spice

I am trying to simulate a flyback transformer in Lt spice having an input voltage of Vin = 12 V, turns ratio = 8.45, coupling coefficient = 0.8. As per the calculation, output voltage should become ...
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Splitting output power of a PFC stage to three flyback converters

I want to design three flyback converters whose input is taken from a single power factor correction circuit based on boost converter topology. The PFC stage delivers 200 W (400 V, 0.5 A), and I want ...
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Understanding flyback power supply with weird snubber circuit, and general function?

Hello fellow wanderers of the electromagnetic plains, I'm looking to replicate the function of the below pictured reference design, just a simple 230VAC SMPS using an iW1700 chip (72kHz operation), ...
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Constant Voltage Applied to Inductor

I'm seeking clarity on understanding what happens when a constant voltage is applied to an inductor. I gave this explanation in another thread and it was regarded as wholly misguided in the following ...
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2 votes
4 answers
171 views

Capacitor between flyback diode and inductor

In my recent endevours in switching regulators I came to understand the need of a flyback diode in non-synchrounos regulators. From my experience with relays I know the flyback diode is placed in ...
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Magnetizing Inductor vs Transformer

I am a bit confused by the diagram - are there two inductors in parallel on the primary side of the flyback transformer? How does no current flow through v1 when the switch is closed?
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5 answers
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Flyback Converter: Where does the reflected voltage come from?

I have not been able to find a 100% clear answer to this question, but here is what I have found: From my understanding, the answer is it comes from the primary side inductor trying to resist the ...
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2 answers
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Inductor Back EMF Direction Relative to Changing Current

I have spent a lot of time thinking about Faraday's law and common explanation as given on wikipedia does not sit well with me. I may be confused. My concern is entirely with the wording of this ...
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2 votes
4 answers
163 views

Methods for high current DC motor emergency cutoff

I need to add a secondary means of cutting off power to a motor for safety reasons if a state change is detected on a 3.3V logic level signal while it is operating. The requirement I have is that it ...
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Snubber diodes on relay h-bridge

For my project I am controlling a motor 12 volt 6 amps (forward & reverse direction) with the help of two SPDT Relays that are controlled by a 2 channel remote as shown below. Where do I put the ...
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How to add a flyback diode to protect a relay on another PCB that does not have a flyback diode

I have a PCB (SEPARATE PCB) that I want to test by building up a "Test PCB". The test will involve switching the relays. This PCB (SEPARATE PCB) has a few relays on it, however, they do not ...
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2 votes
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Which flyback diode for magnetic buzzer

I am a novice, and I'm playing around with SMD magnetic buzzers. For instance, the CUI CMT-322-65-SMT-TR. In the datasheet they recommend something like this: After some Googling I learnt the diode ...
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Tesla coil with flyback transformer and ZVS circuit

I am new to the field of electronics and I might have some wrong concepts. I was thinking of designing an old fashioned 'spark gap' Tesla coil. Materials I have: a flyback transformer a cheap ZVS ...
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2 answers
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Current sense pin detect too quickly (Flyback)

Here is my circuit: simulate this circuit – Schematic created using CircuitLab There is two problems: Firstly, the sense circuit don't open the mosfet at 1V, yet the zener at the V+ in the amp ...
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2 votes
4 answers
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Does a flyback diode have to be connected to the + lead of a solenoid, or can it go directly to the power supply?

I am designing a control box to switch 24V DC high speed solenoids at a max frequency of 200Hz. They will be controlled by an Arduino Mega through N channel, rfp30n06le MOSFETs. Here is a photo of the ...
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Braking a brushed DC motor with a flyback diode

I've seen many references to braking a brushed DC motor by shorting its terminals. As I understand it, the motor torque is relative to the current through it, which should dissipate relative to its ...
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1 vote
1 answer
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Choosing the right diode for my H-bridge?

I'm making a H-bridge for a 12V DC-motor. I have to choose a flyback diode but I have a hard time determining the motor's back EMF voltage. I'm assuming this voltage won't be more than double the ...
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How to calculate auxilary capacitor for flyback

here is my circuit, simulate this circuit – Schematic created using CircuitLab The components try to restart but no results. Vcc output in yellow. I don't find in internet how to calculate ...
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How to calculate power requirement of Zener diode for specific frequency of operation?

I'm planing to control injector from MCU and this is schematics I came up with. Power supply voltage is 14V, inductance of L1 is 0.0014H, resistance of injector 16.6Ohm, and switching frequency is ...
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Rated drain to source voltage of a power MOSFET sustaining back EMF of solenoid

I have an H-bridge that is using 4 n-channel MOSFETs with max rating of 500 V 100 A drain to source driving a large inductor/actuator reliably. I'd like to find a cheaper MOSFET since the 100 A is ...
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