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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54 views

Safely probing low voltage isolated DC/DC converter rails with an Oscilloscope

Lets say you have a flyback with a 20V dc input and 2 secondary side outputs, 5V and 12V. The 20V power in is provided by a benchtop power supply. What is the safe way to measure the input and output ...
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75 views

How do VAC ratings of flyback transformers translate to VDC ratings of flyback converters?

I am trying to design a 40-50W flyback converter but I am struggling to select an appropriately rated transformer. While most flyback transformers are rated in AC volts, plenty of flyback converters ...
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43 views

how to choose diode for PWM of high amperage solenoid?

I'm making a pulseable solenoid circuit via PWM at around 20 hz. THe solenoid is a heavy industrial type that pulls a whopping 18 amps. My snubber circuit gets hot and burns up as the current is too ...
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67 views

What could be the cause of high leakage inductance on my custom flyback transformer?

I've built a flyback transformer by hand for a circuit I am making and after shorting the secondary I have found my leakage inductance is very high. The primary inductance is around 2 mH, while the ...
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61 views

Can I use a back to back Zener as a flyback diode for an AC coil?

I am using the below AC electromagnet to switch on/off a pneumatic system. (It is a pneumatic actuator. I think that is what it is called.) The issue is, when I turn off (disconnect the switch) the ...
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47 views

DC solenoid overheat protection

I got 40 DC solenoids (12 V, 2 A) and each solenoid may be turned on for max. 5 seconds every couple of minutes or even more. Does this implementation require that an overheat protection should be ...
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41 views

No Current Flowing From 12v Solenoid Pins

I have recently designed my first PCB (forgive my poor understanding of electronics) and I'm having an issue with the pins that are supposed to be powering the 12v 2A solenoid. Everything works as ...
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51 views

Flyback transformer temperature rise - reasonable value

I had build an flyback converter based on UC3845 and some high voltage mosfet - it works fine, however I've got one problem with it. (but i'm not sure if that actually is a problem) The core for the ...
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69 views

Polarity independent flyback diode

I am currently building a controller for a slot car track. These work by placing a car on a track on two rails that supply the DC motor of the car with current. The track has an input of 20 V and has ...
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63 views

Energy of flyback with multiple outputs

Where does the additional energy for flyback with multiple outputs come from? It appears that I can add as many secondary outputs as I want, but the primary voltage is Vin, and the primary current can ...
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57 views

Trying to damp transformer output ringing of Flyback Converter when primary FET turns on

I have a flyback regulator with some output ringing spike problems. It is a 70-130V input with 6V regulated output and 75V unregulated output based on the LM5021 flyback IC. When going from no load to ...
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84 views

Simplest way to limit current from MCU pin

I'm trying to build a very simple flyback power supply capable of only about 1mA. The basis is to supply a PWM wave to a 1-1 sepic inductor (shielded coupled inductor). The problem is that it would ...
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552 views

Don't understand the current direction in a flyback diode circuit

I'm aware of that, in a circuit, inductive loads need to be protected with a flyback diode because if the circuit gets open the magnetic field will collapse forcing a current flow in the opposite ...
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44 views

Spark Gap Circuit Creating Unpredictable Current Spikes, What is Causing This?

I have recently been messing around with bug zapper / spark ignitor circuits as a way to learn more about high voltage electronics (This is my first foray into high voltage territory other than a few ...
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45 views

Secondary snubber in flyback converter

I am designing a flyback converter. Input = 180-240 Vac Output = 15 V, 0.4 A The secondary output seems to be oscillating when the diode is turns on. Oscillating frequency is around 27 MHz. I am using ...
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45 views

Voltage drop of free wheeling diode

I have two diodes one has an voltage drop of 0.2v while other has a drop of 0.55v in the same circuit. While I use the 0.55v drop diode for freewheeling (35 Amps diode) and the other diode remains in ...
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47 views

SMPS Transformer Primary Winding Ringing

We are working on a 24V 4A flyback SMPS design. But when we analyze the primary winding of SMPS transformer, we are determining very high voltage oscillations(ringing) up to 350V. But our DC bus is ...
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64 views

Below given circuit, when given 24V DC supply for 30 seconds, the IN5408 diode shorts out at a rate of 1 in 5 cases

With circuit given below, when given 24V DC supply for 30 seconds, the IN5408 diode shorts out at a rate of 1 in 5 cases. This is an EMR circuit. What could be the possible cause for this issue?
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43 views

How to take a nixie power supply and make a low power frequency modulated signal

The project I am working on requires a low input voltage stepped up to a high voltage at a certain frequency and PWM with low power. I found a nixie power supply circuit that can supply 170V at 20mA ...
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166 views

Secondary voltage spike in flyback transformer

simulate this circuit – Schematic created using CircuitLab I am using a TNY264 IC to make a custom flyback transformer. (U1 is the TNY264.) The primary to secondary turns ratio is 10 with the ...
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1answer
120 views

Do ordinary transformers need flyback protection?

Low voltage 12V relays driven by a microcontroller plus transistor need a flyback diode to suppress an inductive voltage spike when they are switched off. Do ordinary power transformers (say, at a ...
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50 views

Detecting absence of current in transformer secondary

Beginner here. I'm trying to build a circuit which charges a capacitor to an arbitrary voltage in the shortest possible time. I want the high voltage part of the circuit to be galvanically isolated ...
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47 views

SMPS transformer secondary voltage drift

Please see the simple SMPS buck circuit below (24V to 12V) Notice the load on the 'first' secondary coil is about 100mA (marked 'fb' This coil is used as the feedback to the MC43063 to regulate the ...
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126 views

Gate signal problem on my flyback

Here is my flyback converter design. Vin: 110V Vout: 24V Iout: 1A (max) Desired efficiency: 85% Transformer -> P1: 6T S1: 6T S2: 5T (aux) Vro: 24V EFD30 I determined 15uH for Lp Ls1: 15uH and Ls2: ...
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29 views

Does a spinning plasma vortex work with ac?

I am making some plasma arcs with this flyback transformer and I power it by passing the exposed wires of my charger to a halogen ballast. I've seen people online make spinning plasma vortexes I was ...
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44 views

Flyback 120-240VAC to 3.3VDC ripple and simulation

I'm working on a project requiring a 3.3VDC and eventually a 12VDC. The input voltage could be either 120VAC or 240VAC 60Hz. I've found and replicated the design PMP10143 proposed by Texas Instrument ...
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41 views

Reduce capacitor charging time

i am using flyback converter to charge a capatior 250uF 300V how can I reduce the charging time to 1 second OR how to increase current. 28V DC input voltage transformer output Voltage is 300V PWM ...
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512 views

Why is inductive kickback not V=IR?

I'll preface by saying I'm aware of questions like these 1, 2, and 3, but none of them answer my specific question. All of these questions say that the kickback from an inductor can be given by: \$V=L\...
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76 views

Small signal analysis - Flyback transfer function - LTspice

I am trying to simulate the transfer function of a Flyback by using LTspice. The flyback that I am trying to simulate is a flyback which can be found into the book "Switch mode power supplies&...
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127 views

Can measuring back EMF spikes damage the oscilloscope?

I want to measure the voltage across an inductor as soon as I disconnect one of its terminals to visualize how back EMF changes with and without a fly-back diode. From videos on Youtube: https://www....
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129 views

How can I use the voltage generated from inductive kickback?

I'm designing a circuit that requires a high voltage pulse in order to fire a spark plug. I'm thinking of using an inductor to provide this pulse (via inductive kickback), but I'm struggling to figure ...
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54 views

Optocoupler ac model ltspice

I am trying to plot the bode diagram of a flyback converter on LTspice. This is the first time that I do this and before trying to plot my flyback converter, I would like to plot the bode diagramm of ...
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47 views

Appropriate solenoid valve flyback diode

I control a 24V solenoid valve via PWM controlled MOSFET. I have a 1N4007 diode parallel to the solenoid. If I put a 2.2uF electrolytic capacitor directly next to the solenoid it works properly, ...
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47 views

Flyback diode and MOSFET rating vs DC motor stale current

I'm trying to determine a suitable flyback diode for a DC motor controlled by a N-channel MOSFET. The specs the motor read: ...
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79 views

A few questions about flyback dc-dc converters

I have a few questions regarding this flyback converter simulated in LTspice. 9V was stepped up to 27V using the transformer. My questions are: Why didn't the output voltage change with the change in ...
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34 views

Designing a compensator - Control system - Missing value

I would like to determine the transfer function of the following circuit made of TL431. According to the different AN that I have read (and about this subject I really really thank Christophe BASSO, ...
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43 views

Determining error in output voltages of a flyback converter

I'm currently designing a flyback converter and I just want to know how the error tolerances are calculated for a multi output flyback converter. I calculated the required primary number of turns: ...
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94 views

How can I make my flyback converter discharge immediately?

I'm using a flyback converter (220-100V to 19vdc) to power an electronics unit. But it doesn't discharge fast enough, this causes some relays to stay energised for a second or two after power supply ...
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24 views

Flyback converter Transformer calculation verification

Kindly verify the transformer design for this wide input power supply using LM5022 i am designing the power supply for my solar inverter in which output of solar panel (750Vdc to 800Vdc) directly fed ...
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1answer
94 views

Getting an unencrypted PSPice PSU Control IC working in LTSpice

I am currently working on a flyback converter design based on the TI UCC28C42 multi-topology controller IC, and would like to simulate my circuit in LTSpice. I have created a small-signal averaged ...
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490 views

PCB Design position of flyback diode for motor

I have a simple question: If I design a PCB, does it physically matter at what position my flyback diode for my motor is? Does it matter if it's "in front" of my MOSFET or not? I made two ...
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85 views

Why is there a huge difference between Is2(peak) and Is2(rms) in flyback converter?

I try to design a flyback converter which has two outputs. First output is main output 24V/1A and second output is for Vcc 18V/0,02A. Total output power -> Po = 24,4W Efficiency = 85% So, input ...
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108 views

What is this transformer, is it package only without coil or complete transformer?

I did a simulation on TI Power Bench for a isolated power supply, There I got transformer spec in BOM, Core=Wurth Elektronik , CoilFormer=Wurth Elektronik Core=150-2340 , CoilFormer=070-4477 Core Type ...
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64 views

Is there a way to know if there is a flyback diode?

I have two 12V water pumps that I want to control with an Arduino via a relay. They are generics and I am unable to find a reliable datasheet: Good Pumps with Rohs Motor: Goso GB37-530 Is there ...
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110 views

Back EMF in sensored BLDC motor

In hall sensor based BLDC motor, motor is controlled by feedback of hall sensor. At a time only 2 stator pole pairs will be excited and 3rd pair will be ideal. So in third pair Back EMF will be ...
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116 views

Isolated Flyback vs Isolated Buck Voltage converter. What are the Pros and Cons?

I am working on a project where I need an isolated power supply. My input is 10-20V and I am looking to get an isolated 3.6V out @ 5A or more. My priorities are easy of implementation, voltage ...
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125 views

TVS flyback diode placement

I'm switching a solenoid with a relay. The relay has failed after just a few hundred operations, I suspect because of the flyback from the solenoid. I have a P6KE20A TVS diode that I want to use to ...
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64 views

ESD Protection for flyback diode - Relay circuit

I am designing a board to accommodate relay and flyback diode with IO connector in a PCB. The low side driver of relay will be present in another PCB. Both the boards will be connected through wires(...
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70 views

Why did the designer of this flyback circuit choose to set the oscillation frequency as high as possible with the smallest resistor tolerated?

This circuit uses a current mode controller with an oscillation frequency response of: In the circuit, the designer chose to use a 10nF cap, with a 680 ohm timing resistor, which according to the ...
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96 views

Do I need to suppress ringing in a flyback converter?

I am about to design a flyback converter. As all flybacks with no extra measures it has some ringing. You can see that ringing in this example from -1µs to 4µs: This ringing can be surpressed by a ...

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