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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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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152 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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60 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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203 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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97 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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54 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
73 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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76 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
76 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
302 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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56 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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43 views

Flyback loop design and compensation

I have a problem. I am designing flyback converter on VIPER27. And I have problem with feedback loop because I don't know, I mean... I don't understand how I should choose a values of the components ...
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99 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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138 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
81 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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3answers
118 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
60 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
84 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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0answers
75 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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101 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
74 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
95 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
96 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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147 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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339 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
216 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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722 views

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 ...
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36 views

Do I need to place any additional component(s) getween isolated grounds?

Initially I bothered with this question regarding isolated flyback switch mode power supplies. However I'd be happy to investigate this question dipper. So as the output of the power supply is ...
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516 views

Determine adequate speed of flyback diode for a relay

I have already looked at this question which looked like it would provide the answer: How to choose a flyback diode for a relay? But it didn't, so I also checked out these: ...
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2answers
132 views

Is a flyback diode necessary when no sensitive chips are used?

I have had a look through all the information available about flyback or snubber diodes in a relay system and was hoping to confirm if one is necessary in my circuit or not. All the info about why a ...
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3answers
170 views

Relay Spike at Vdd

I have a problem with voltage suppression at the time of relay switching. I use a transformerless ac to 12v dc conversion circuit similar to (I use 12V zener and 470uf capacitor) : ![enter image ...
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0answers
89 views

How can I add redundancy to the flyback diode protection across an inductive load?

Dear StackExchange users, I want to add redundancy to a flyback diode system that is protecting an N channel MOSFET from flyback of an inductive load but I don't know how to accomplish this! I am ...
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1answer
130 views

ESD protection on a solenoid driver circuit

I have a breadboard circuit that controls some solenoid valves and am trying to move it to a PCB along with improving it for ESD and EMI. This is the circuit I have on the breadboard that I want to ...
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164 views

How different is the performance of TVS vs Zener diode in flyback protection

So far I know that it is possible to protect a Switch, MOSFET, Relay from flyback with different kind of diodes: One diode: It is simple but it affects the speed of valve One diode + a resistor: ...
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255 views

How does flyback diode decrease the response time of a solenoid valve

Dear all StackExchange users, I want to make a circuit consisting of 8 valves. Each valve has 55mH and 33 ohm. I want to control them with an Arduino board and a proper MOSFET. Valves reaction time ...
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1answer
34 views

Does zxms6004ff come with flyback diode internally?

As question above, does anyone know better about product from DIODES? I am using zxms6004ff, but not sure about if it comes with flyback diode internally? I read over their datasheet. It only says it ...
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109 views

How to calculate discharge time of DC motor via flyback diode in H bridge

The setup is as follows: DC Motor: Brushed DC Motor PNP NPN standard H Bridge with 4 numbers of 1N4448 for flyback protection. Stall current of the Motor: 200 mA (Stalling is expected) Typical load ...
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2answers
119 views

Relay noise problem although flyback diode is used

I've this relay (5V) with 1N4148 as flyback diode across the relay's coil but there's still noise problem. When I switch on/off the relay, the PIC MCU will occasionally reset and false triggered the ...
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1k views

Can a Zener diode that protects a switch against inductance when the switch opens, affect turn on speed of the valve when you close it again?

As you probably know, in the applications that the turn off speed of the solenoid valves are crucial, the simple flyback diode is not effective. Some people put a resistor in series with the flyback ...
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1answer
108 views

Procedure for finding the right MOSFET, diode and resistor to make a solenoid valve open/close? [closed]

I need a right MOSFET to make a 8 valves open/close about 15 times per second! It needs to switch very fast. Anything that can slows the speed of the valves is not desirable. From what I see the ...
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3answers
128 views

best way to rectify 30kv flyback output?

i have made a flyback transformer for some HV experiments and am hoping to get around 35kv from it, which i want to use to charge a capacitor, so i will need to rectify the output... i think perhaps ...
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1answer
107 views

Why do Flyback Transformers have C-I cores?

Usual transformer cores are either E-I or E-E. What's the reason for Flyback's being only C-I? Does it simply cut the cost?? I want to know if it would perform less if it were an E-I.
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731 views

Resistor instead of flyback diode

I was looking at the data sheet of a common 12v relay and noticed it mentioned using a resistor instead of a flyback diode for circuit protection. On the last page for 12V models it reads; When ...
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31 views

What are important parameters for a flyback diode? [duplicate]

I need a flyback diode for a 12V/50mA relay that is switched by a BSS138 MOSFET. Do I need one or more of the following: Schottky diode fast recovery diode high current diode or would a 1N4001 or ...
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2answers
348 views

Where to add Flyback diode?

I have made a relay controller module which switches a automotive relay when a ULN2003A sinks current on the separate main board. The module is in an always active state, but the requirements have ...
2
votes
1answer
192 views

Standard transformer for higher-voltage dual output flyback converter

Is it possible to modify this flyback converter to get the output voltage somewhere up in the range of +/- 26-60v (preferably 30v or more) without having to make my own transformer? I would also like ...
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1answer
529 views

Flyback transformer pin connections

I took a flyback transformer out of an old CRT television. This is how it looks like on the top: And this is how it looks like on the bottom: http://i.imgur.com/8QYwPhQ.png W1 is a thick red wire ...
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2answers
191 views

Is this the behavior of a broken mosfet?

I designed this circuit to switch on/off 8 solenoid valves for a programmable dancing fountain that I am building. The GPIO is coming from a Raspberry Pi. VCC is coming from a 12V deep cycle car ...
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1answer
175 views

Flyback Transformer Saturation in Secondary

I am trying to select a flyback transformer for a prototype I'm designing. Almost all flyback transformer data-sheets I've seen provide only the saturation current for the primary winding. The ...
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2answers
201 views

Trying to understand flyback diodes and general diode orientation

Let's start with this: I know the top image is of a flyback diode. I also get that its purpose is to protect the power supply from a voltage spike when the electromagnet releases. So I've gotten ...