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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Buck-Boost Controller Arduino Nano vs STM32

I have 900W (150W*6Panels) solar panels and 12V inverter (1000VA) which have inbuilt PWM solar charge controller. The distance between pannels and inverter is around >10m and the wires are 6 sq mm ...
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2 answers
123 views

Why does the signal and power supply in my custom ESC breadboard become so noisy when the motor is rotating?

I am building a custom ESC to drive my BLDC motor. The motor spins in open loop and I want to debug the back-EMF detection circuit, but as soon as the motor spins, the signal line of the MCU (MCU uses ...
1 vote
1 answer
74 views

Over-power protection circuit

About NCP1342, there is a protection circuit which was called Overpower Protection (on page 14). I am confused about why this is over-power protection. There is no circuit to do the multiplication, I ...
3 votes
1 answer
2k views

How can I build a high voltage (2-6 kV), high frequency (20-50 kHz) power supply?

I need to make a high voltage (2-6 kV), high frequency (20-50 kHz) power supply in order to generate cold plasma (in argon gas.) I used a flyback circuit (found on the web.) The high frequency is ...
1 vote
1 answer
385 views

Transformer construction diagram

Controller datasheet Can anyone explain how the actual winding happens? The transformer is a shell type transformer used in a flyback circuit. The circuit is not working, and I'm suspecting the ...
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1 answer
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Trouble shooting ZVS driver

I've posted a few question on this forum about ZVF drivers and you all have been a big help and I'm hoping you can help me again. Forgive me if this is a bit long, I just want to be through.   Above ...
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35 views

Leakage Inductance Delays the Secondary Current

I read Basso's seminar, on Page 30, it is talking about Leakage Inductance Delays the Secondary Current. From the formula, we can get the Δt, but I am curious about one thing if we don't add the RCD ...
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Flyback Converter Valley Switching and QR mode

I watched TI's basic flyback video about the different control methods. and I am confused about some things, please see mine below questions. 1.) Valley Switching and QR, last time I ask a question ...
5 votes
2 answers
603 views

Why can't flyback work when the duty cycle is greater than 0.5?

I read this document talking about flyback design, and I am curious about why, when the duty cycle is greater than 0.5, do we need to adjust the VOR to make sure the duty cycle is less than 0.5? What'...
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2 answers
47 views

Flyback Frequency Foldback Mode (FFM) and Skip Mode

I would like to know why flyback needs to use Frequency Foldback Mode (FFM) and Skip Mode. I did some research but I don't understand the details of what I've read. Below is a figure that I found in ...
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1 answer
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ZCD SIMPLIS function block questions

I find the figure which used to do the ZCD circuit. please see the below figure. Does anyone know what's name of U7? I can't find this module in SIMPLIS. I would like to use this way to do the ZCD, ...
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1 answer
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How does this high voltage device work? [closed]

In Ali express, I found the following high voltage small generator for fun. One transistor, one single coil, 2 caps and 2 resistors (not sure if the leds are an essential part of the circuit). The ...
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2 answers
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Why are the vertical deflection coils in a CRT deflection yoke so different from the horizontal coils?

Looking at a typical raster CRT deflection yoke, there appear to be two very different pairs of coils. There is the pair on the inside that curves outwards, and the pair on the outside, which are ...
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1 answer
141 views

JDS6600 signal generator - broken or normal?

I recently treated myself to a JDS6600-60M signal generator. It's a (very) cheap one but that's because electronics is just a hobby and not something I make money with or anything. The other day I ...
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2 answers
1k views

SMPS Flyback transformer selection

I am trying to design a SMPS for a project (I have to make a custom one for integration purpose). This SMPS have universal input (85-265V AC at 50 or 60 Hz) and an output of ideally 53V (but it can ...
1 vote
2 answers
59 views

LM311 ZCD out to LM555 reset

I have no background in electrical engineering other than curiosity; I'm more of a copycat. I have been trying to reproduce this schematic: I have searched the forum but don't see anything remotely ...
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1 answer
362 views

Designing flyback converter - multiple isolated outputs

Can I treat 2 secondary coils with dual voltage output as one with double voltage for the purpose of calculations? This seems to be OK for all formulas based on output power as technically the ...
2 votes
2 answers
215 views

Flybuck converter at high power

It is said that the flybuck topologies are cheaper than the flyback topologies. This is due to the fact that there is no need to have an optocoupler, the regulation is said to be simpler and probably ...
0 votes
1 answer
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Issues Choosing Flyback Transformer Specs & General Direction Help

I'm working on trying to figure out how to wind transformers myself and picking values etc. I currently have PQ26/25 Bobbins with PC95PQ26/25Z-12 ferrite cores (N95). I have some smaller E cores ...
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1 answer
77 views

Is it possible to use an MOV instead of a flyback diode in a pulse circuit?

I am working on a small high-voltage pulse circuit to protect my animals. I have a question about the flyback diode D2 to protect the SCR. The flyback diode seems to waste a lot of energy between ...
1 vote
1 answer
66 views

Salvaged magnetic materials for low performance 1MHz boost converter

I am wondering if I could modify a MT3608 boost module by winding a custom inductor / transformer for it, to generate a kV range voltage (at sub mA current). I'm thinking of replacing the 22uH ...
1 vote
1 answer
473 views

Reduce Flyback Reflected Voltage Ringing?

I have a step-up flyback design with the following parameters: \$V_{in}=24V\$ \$V_{o}=150-350V\$ \$P=15W\$ \$N_{ps-ratio}=1:7\$ The transformer is not ideal with 1:7 and the inductance is a bit off, ...
2 votes
1 answer
229 views

FAN6754 flyback converter-overcurrent problem

I have a flyback converter design with a 193 V output voltage and 700 mA current, but when the current is drawn from the output, the auxilary winding voltage falls down, and the IC shuts down the PWM ...
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32 views

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, ...
61 votes
4 answers
159k views

How to choose a flyback diode for a relay?

A diode is put in parallel with a relay coil (with opposite polarity) to prevent damage to other components when the relay is turned off. Here's an example schematic I found online: I'm planning on ...
1 vote
2 answers
56 views

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 ...
6 votes
3 answers
309 views

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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1 answer
230 views

Flyback converter primary and secondary sides power calculation

The problem is as below. Input DC voltage is at 12V, transformer inductances are: Lp = 60uH, Ls = 240uH, switching behaviour is controlled by a single NMOS with switching frequency at 60kHz. For ...
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1 answer
90 views

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.
3 votes
2 answers
2k views

Transformer maximum voltage rating specifications

I don't know how to interpret the voltage values found in datasheets for transformers. For example, in the datasheet below: where it says 15v, 50mA near the winding schematic. Is this a maximum or a ...
1 vote
2 answers
647 views

BJT Collector-Emitter Breakdown Voltage

I'm developing a flyback converter with the FT838NB1 IC, and I got some doubts about the Collector-Emitter breakdown voltage of the integrated NPN switching transistor. IC datasheet link: https://...
1 vote
1 answer
529 views

Cascode MOSFETs for high voltage

In this circuit, the HV+ point ranges from 100 to 1200 VDC. The two MOSFETs are rated at 800V, which makes 1.6kV breakdown. D7/D8 are 300V each, so they have a clamping voltage of 600V. My question is:...
1 vote
2 answers
73 views

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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1 answer
57 views

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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3 answers
137 views

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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3 answers
340 views

Snap-On impact driver Flyback Diode identification

I have a Snap-On impact driver with a blown diode. I believe it's a flyback diode as it's on the output of the switch up to the motor. I can make out several markings on the diode. C39 and C5, there ...
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1 answer
73 views

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 ...
0 votes
1 answer
1k views

Half bridge DC-DC converter circuit analysis

I was trying to learn how the flyback and half bridge DC-DC converter is working. For Flyback circuit, Understood output waveform is as follows. Keeping this understanding in mind, I was trying to ...
2 votes
1 answer
363 views

Flyback converter can't power load

I'm working on a Nixie tube clock and I'm having issues with the power supply. It's a flyback converter based on the LT3757 and the Coilcraft DA2032-AL flyback transformer. I designed to work with an ...
1 vote
5 answers
294 views

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 ...
-1 votes
1 answer
75 views

555 flyback - question about efficiency

How can I improve this scheme to reduce consumption? MOSFET is 4N0403
2 votes
1 answer
127 views

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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0 answers
68 views

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 ...
0 votes
3 answers
1k views

Flyback simulation - not regulating at lower load

So I've been trying to simulate a flyback converter with the full load condition of 10v, 10A (100W) at the output at fs = 80kHz. The design equations I used were from "Pulse-Width Modulated DC-DC ...
1 vote
1 answer
75 views

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 ...
1 vote
3 answers
1k views

DC motor PWM control and flyback diode question

Suppose we are controlling a DC motor via PWM. The motor has a flyback diode across it. Question: During the PWM off period, the motor current freewheels through the diode. Won't the motor experience ...
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1 answer
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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 ...
1 vote
1 answer
385 views

Sizing zener and resistor for solenoid flyback

I am trying to drive a vibratory pump from a 220 V boost converter (the common 150 W DC/AC 12 V to 220 V boost converter found on ebay) and a MOSFET switched by an Arduino/optoisolator at 50 Hz. The ...
1 vote
1 answer
90 views

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 ...
0 votes
1 answer
37 views

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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