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 ...

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Designing an High Amperage, Low Voltage AC Voltage “Breaker” for Model Train

I’m trying to build a simple circuit that acts as a "voltage breaker" – meaning that if a voltage exceeds a certain threshold, analogous to a (current) circuit breaker it will open a circuit. There ...
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197 views

What is a flyback?

Trying to find this answer is so difficult that I can't even tell whether What is the difference between a transformer and a coupled inductor? is asking the same thing. Some reading suggests that a ...
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2answers
61 views

Buck converter after 50Hz transformer

I plan on designing a variable power supply (1-50V, isolated), able to provide a power of about 50W. For efficiency's sake, linear regulation is out of the question. The natural thing would be to ...
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38 views

Generating varying output voltage [on hold]

How do I generate a varying output voltage (40-80v) from an input voltage of 50V? (DC-DC) My input current is about 25A. Can it be done using flyback if I want to generate a power of 600W? What are ...
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54 views

Dealing with FreeWheel Current

In the schematic below, I would like to know the best way to dissipate the FreeWheel Current in the very shortest time possible. simulate this circuit – Schematic created using CircuitLab ...
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30 views

Specifications for a flyback transformer

I'm building an SMPS that takes in 110/220V AC and outputs +/- 3.3V DC. The chosen topology is flyback and as is the case of flyback transformers, I need to get one custom made. I have the Np:Ns and ...
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18 views

What type relay should I use?

I want to close a switch with a pulse, stay closed until I send another pulse from a different circuit. Would form-A duel coil latching relay work?
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1answer
34 views

Good choice for a flyback diode [closed]

I have a relay with following ratings: coil voltage 3V coil turn on voltage 2.1 I have looked at IN4007 but they are available in bulk quantities only. Can anyone suggest any other diode?
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41 views

Power supply - Boost voltage over distances

I'm looking for a good power supply design to boost the DC voltage and convert it to AC so it can be transported over a long distances with low loss. I have drawed a example picture: The only thing ...
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37 views

Working with freewheel Current

Andy aka, rioraxe and Daniel thank you very much for taking the time to respond to my first question. In the schematic below, an A/C voltage is induced in the inductor. The MOSFET is used to control ...
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3answers
108 views

Correct placement of freewheel diode

I have two questions on placement of freewheel diode in a H-Bridge circuit: 1) In reference to the general H-Bridge circuit below, wouldn't it be safer to place the freewheel diodes directly across ...
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67 views

1N5819, 1N4007 or 1N5408 as a Flyback Diode

I'm using a DC-DC buck converter to drive a motor having an inductance of 3mH. Flyback diode becomes necessary across the motor to provide a safe path for the energy stored in the collapsing magnetic ...
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2answers
45 views

Flyback across PMDC motor

A PMDC motor M2 is connected to a constant regulated voltage source. To protect the regulator chip from the flyback voltage, a diode has been added. From the same unregulated voltage source another ...
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1answer
45 views

Error amplifier in dc dc converter chip

I am trying to design a dc-dc converter using the UC3844 IC. The working is clear to me. But the datasheet has an application circuit that is a bit confusing for me. The datasheet. The circuit in ...
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1answer
36 views

Flyback transformer selection

I am designing a flyback converter using the PA3855.004NL transformer. Now, the datasheet screenshot is as shown below - . There is a value of 4.33 in the primary of the transformer. Is it the ...
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0answers
41 views

selection of transformer for flyback converter

I am designing a flyback converter. Now, necessary parameters are as stated - Vin(voltage to primary) = 17-32V, Vout(voltage to secondary) = 12V, Iout = 3Amps. Now, based on the above requirements, ...
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106 views

Direction of winding (clockwise/anticlockwise) in flyback transformers

Here is a circuit of offline switching power supply based on Viper22a IC: In this circuit and many other similar circuits, they denote the starting of a winding by a "dot". However they never ...
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76 views

Self Oscillating Flyback Converter /w Adjustable Output Voltage

I'd like to make a 36V-3A direct offline self oscillating flyback converter for my own use. The following is the simplified schematic (I didn't show protective elements, fuses, current limiters etc.): ...
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46 views

Calculating flyback diode values

I'm designing a small herb garden automation system as my first hobbyist project in electronics engineering. I'm still very new to this stuff. I have two general questions but am supplying my early ...
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1answer
71 views

Flyback converter

I am designing a flyback converter based on the UC3844 chip. As a starting point, I went through an eval board that is given in the Microsemi website. The schematic of the design is as shown below - ...
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0answers
23 views

Flyback Controller

I want to understand the basic relation between the regulation and efficiency of a converter, flyback to be specific and how is it really related to the sense pins of the controller IC. From the ...
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1answer
94 views

Flyback converter for a step-up application (4VDC to 48VDC)

From what I have seen, flybacks are used for step down applications, are step-up applications possible? More specifically, is converting from 4VDC to 48VDC possible using a 1:8 transformer? I'm ...
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2answers
66 views

How signficant is leakage inductance in a flyback converter?

In designing some flyback DC-DC converters (to give us isolation), we have been simulating potential designs in LTSpice, which has gone well. (Isn't LT great at documentation? Pretty much perfect ...
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1answer
75 views

flyback converter transformer selection [closed]

I am trying to design an isolated dc dc converter. Now, my input is approx 20V and I need an output of 7V at the final output. I understand that I need a PWM controller that is approx 100kHz or so. ...
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1answer
33 views

Diode preventing coil from latching?

So I've come across a case where an input from a little 5v I/O system will trigger the coil of a reed switch but not it's direct equivalent that has a built in flyback diode and changing the resistors ...
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170 views

long wire kickback voltage problem

the long wires acts as inductor which shutdown and sometimes damage my microcontroller(IC1), for the AC part ill be implementing an optoiso along with triac and snubber circuit (lemme know if you ...
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161 views

Can a “distributed gap” powdered-iron or ferrite toroidal core be used for a flyback converter's coupled inductor?

As just about all of us who deal with switching power supplies know, flyback converter designs use an air-gapped coupled inductor instead of a transformer. Typically, this gap is an explicit gap in ...
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937 views

SMPS schematic - transformer calculator

I found this schematic for a simple SMPS. I want to use it to build a 24V/2-3A power supply for a soldering station. How are the turns on the transformer calculated? For the primary I can use N = ...
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2answers
156 views

Current flow in a simple flyback topology

I'm continuing my learning about flyback converters, and trying to understand the current flow and the magnetic fields involved. For instance when the mosfet is on current will flow through the ...
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3answers
142 views

bi-directional flyback diode for relay spike protection

A flyback diode is used to protect circuits against the reverse voltage generated by removing power from a relay coil. Like this: simulate this circuit – Schematic created using ...
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2answers
100 views

Danger of Saturation of Primary Coil in a Flyback

I was reading a book, "switching power supply design - Abraham Pressman", specifically the section about flyback converters. One part I'm not quite sure I understand is where he says that the ...
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81 views

is a 555 timer flyback driver lethal?

i have always heard on websites that the 555 timer flyback driver is not lethal. i know that the common ZVS driver is lethal but would the 555 flyback driver be able to deliver a deliver a lethal ...
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1answer
105 views

High Voltage Power Supply Design

I need to charge a 1000uF 400V capacitor bank off of a 7V LiPo battery within roughly 5 seconds, and have the circuit be as small and light weight as possible. With a constant voltage supply and a ...
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1answer
927 views

Transformer and IC heating in Viper22a SMPS design

I have designed an SMPS using viper22a IC. This gives an output of 9.8V and on adding a 10 ohm load resistor, voltage drops to 9.6V, thus giving an output of almost 10 watts. Here is the circuit that ...
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78 views

Fuse resistor type

I want to build a flyback SMPS based on "TNY274". About the fuse before bridge, I don't know what kind of resistor should I use for correct operation! Metal oxide film or Metal film or Thick and thin ...
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2answers
145 views

Freewheeling Diode in Bidirectional Motor

I want to drive Brushed 12Vdc, 4A motor using two relays to achieve direction control. But what is the best way to connect freewheeling diode to it, I came up with this circuit. Is it the right way ...
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1answer
167 views

Check for if I've picked the correct flyback and zener diodes for a solenoid valve driver

I want to use an arduino power driver shield which contains the RFP30N06LE MOSFET to drive the 12V version of a solenoid valve which has a power consumption of 2.0 Watts (so 167 mA current draw I ...
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2answers
94 views

why L6565 has input range of 80v-240v? Why not 12v-240v?

L6565 Data sheet specifies that input range starts from 80v to wide range. Why the range does not start from 12v? Is it possible to make it to input from 12v and up?
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163 views

Flyback Transformer Troubleshooting

We have been trying to figure out for weeks why these flyback transformers keep failing. They are these specific transformers http://www.pca.com/Datasheets/EPC3205G-X-LF.pdf We are running them at ...
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1answer
69 views

Question about fly-back diode

I read an article from wikipedia about freewheeling (flyback) diode which is used to drive a relay. I understand it but I have four questions. Would you give me a hand, please ? 1- Why does the coil ...
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3answers
94 views

L6472 step motor driver and flyback diodes

I plan to use the L6472 step motor driver but I'm not sure if I should use flyback diodes connected to the driver output side. The step motor will be bipolar with the following specs: The L6472 has ...
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108 views

Fly-back converter

I'm trying to get 2 isolated outputs (5V and 3V from 12V DC supply) using a single flyback converter by adding one more secondary winding on the flyback transformer. Following is the Simulink model ...
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0answers
158 views

Flyback Transformer Active Snubber Design

I'm using a flyback transformer along with the LT3750 controller by Linear to charge a capacitor. I'm wanting to increase efficiency and improve the circuit. I began with looking into an RC snubber to ...
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1answer
92 views

How to determine correct replacement transformer for flyback converter in commercial product

I have an MPPT charge controller that has recently started behaving strangely and upon investigation I found a very hot mosfet and a transformer (below) that has clearly seen more heat than it should ...
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1answer
135 views

Two flyback diodes in parallel across a relay coil?

I'm using relays that contain a flyback diode internally, so no need to add an external flyback diode. However, I want to provide a place on my PCB to possibly stuff a flyback diode in case I would ...
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1answer
113 views

5V-5V isolated and load regulated power supply

Hi all Requirement: 5V-5V isoltaed and load regulated power supply, load current-0-500mA I am getting 5V output at no load, but when load increases output voltage decrease rapidly and at 500 mA ...
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1answer
181 views

About Fly back diodes and motors

so here's the situation, i have a motor and i am controlling it with a bunch of transistors and an arduino, so i think i need a flyback diode to protect the transistor and my arduino, problem is i am ...
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1answer
698 views

simple induction heating circuit problem

Update: got it working... Fix: replace diodes for proper schottky. Result: got oscillation but no resonans. Fix: replace cap with 1 uF polystyrene. result: got resonans. But now my problem is i cant ...
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1answer
479 views

Do I really need a flyback diode when using a power mosfet?

I am using one of these IRF1404 Power Mosfet and looking at the datasheet I see that the continuous source current (in the Source-Drain ratings section) is rated at 202A!! I will be using it to drive ...
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Making LM78xx fail safe against short, open, reverese bias, flyback, etc

I want to use LM78xx for various applications. What I am concerned about is its failure modes. 1. Failure to Short Not shorting Vcc to ground!! I mean shorting V_input to V_output. Assume that ...