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1answer
27 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 ...
0
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1answer
54 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 ...
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3answers
88 views

Is a flyback diode needed if there are only inductive components on the circuit (Ex. solenoids)

I'm using relays to drive a circuit of solenoids. Do I really need flyback diodes on the controlled circuit if there are only solenoids on it? The driving circuit is already protected by flybacks. ...
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1answer
47 views

Derive Parameters for Unknown Flyback Transformer

I am designing a 1.7 kV @ 6 mA flyback power supply. The issue I have is that it seems to be extremely difficult to find any type of high voltage flyback transformers for the design. I bought a cheap ...
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4answers
82 views

Connecting a galvanometer directly to a microcontroller's PWM output

Is it a good idea to connect a galvanometer (100 µA panel meter) directly to a PWM output of a microcontroller (or any other digital device for that matter)? I set PWM frequency to approximately 10 ...
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4answers
107 views

Alternative ways to catch an inductor's flyback current

This guy had a bit of problem installing the flyback diode to his relays due to physical obstruction. Now if that is really an issue will this be a good alternative way, for perfboards and ...
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2answers
109 views

H-Bridge flyback diode selection?

I am wanting to make a motor driver using a SN754410 Quadruple Half-H Driver IC. The SN754410 requires external flyback diodes. Here is an example circuit: My question is, how do I choose which ...
2
votes
1answer
78 views

Can varnish affect the performance of the air gap in an SMPS transformer?

In the past I have built several switched-mode supplies using off-the-shelf transformers just using the datasheet properties without having to worry too much about their construction, however I am ...
0
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1answer
103 views

SMPS Transformer - Secondary voltage rating

I am designing isolated flyback converter with input voltage range 40VDC-110VDC, 5V/6A output. I am struggling with finding appropriate transformer since each and every one I found have lower primary ...
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0answers
58 views

Flyback (?) diode on the Solid State Relay output

I am looking at the recommended wiring diagram of this SSR and I am wondering about the diode connected in parallel to the load. Flyback diodes for inductive loads make perfect sense to me, but in ...
0
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1answer
89 views

High Side PWM motor driving circuit

I have two theoretical question about my circuit (that I have tested with a breadboard and it works, but I want to understand better some design choices): 1) As far the flyback diode is concerned, I ...
7
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3answers
234 views

Protecting microcontroller from inductive loads

I'm working on a project where I will be controlling a variety of loads (relay, solenoid, motor) from an Arduino and I'd like to make sure I build in enough protection for the microcontroller and ...
0
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1answer
108 views

Will a flyback diode prevent an analog MCU input from being destroyed in this schematic?

Quick question: In this schematic, would D1 prevent high flyback voltages caused by the motor going into the voltage divider network and destroying pin A0 on the MCU? Pin A0 can only tolerate 5V max. ...
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0answers
125 views

PNP BJT as a 'switchable' flyback diode?

I have an automotive ignition coil which I'm using as an ignition source for a project I'm working on. During normal operation, the primary coil current will be interrupted periodically to induce ...
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0answers
89 views

PWM and flyback diode dependency

I have to choose components for a pcb motor driver, there is a dependency that I have to take into account between the PWM frequency and the speed of the flyback diode? If yes, what it is? Thanks
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2answers
271 views

Circuit Protection re: Relay Coil

Is the flyback diode adequate protection in for the microcontroller in the following circuit? simulate this circuit – Schematic created using CircuitLab Will my circuit experience over ...
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2answers
103 views

Low noise voltage regulation

I have a circuit which currently runs off of either a 12VDC wall wart adapter, or it falls back to a 9V battery if the wall wart adapter is not connected. My circuit currently uses a chip which ...
1
vote
1answer
75 views

Flyback converter current flow?

If you look at the flyback converter circuit above, the current only flows in one of the coils at any instant of time. What stops the magnetic field generated by the coil in series with the MOSFET ...
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1answer
52 views

ZVS transformer output voltage [closed]

I was running a simulation with: http://www.falstad.com/circuit, this is my circuit: http://pastebin.com/QKZ6gevy. When I add a capacity, the voltage is not going beyond 50-60V at the end of the ...
1
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1answer
114 views

ATtiny85 absolute ratings for outputs?

The ATtiny85 datasheet specifies an absolute maximum negative voltage for any pin of -0.5 volts relative to ground. Consider this partial schematic: MOSI and MISO are the respective ATtiny85 pins ...
0
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1answer
81 views

Function of UCC2813-1 in flyback converter

I am studying a design of a fly back DC-DC converter. It is based on TL431 voltage regulator with PC817 opto-coupler. I heard that it is a popular design used. Switching PWM pulses are generated ...
0
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1answer
75 views

Inductances in flyback transformer

I am simulating flyback dc-dc converter in multisim software tool .. I want to know the difference betweem primary inductance and magnetising inductance , also secondary leakage inductance?
2
votes
1answer
95 views

Catch diodes in switch mode power

I am wondering about catch diodes in the context of switching power supplies. I have read all the books that are the norm in designing a SMPS, but all of them don't or barely touch the subject. My ...
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3answers
140 views

1:1 and flyback transformer at low frequency and high temperature

I am designing a circuit in that I need 1:1 and fly-back transformers at low frequency (0-100kHz) and high temperature. Can anyone help me with these? I am looking for voltage being handled around ...
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2answers
160 views

What is the reason my ULN2003A overheats?

I'm driving some 12v fan motors from a microcontroller using ULN2003A Darlington array. Both total wattage and per-channel wattage are way below ULN2003a limits. Still, I found that when PWM duty ...
0
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1answer
293 views

Flyback NE555N driver and mosfet overheat

I have built a small and very simple flyback SMPS based on NE555N IC. The circuit exactly I did built from is shown below: It works nicely for small loads. However I have some issues with it: ...
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2answers
318 views

Flyback SMPS Transformer choice

In several projects so far, I have been using old "fashioned" transformer based power supplies. However, this time around I want to use a switching mode power supply. The supply will be used to power ...
1
vote
1answer
67 views

Power supply for a LED driver

I'm working on a project in school were I have the PMP4862 circuit as a reference. Unfortunately the flyback is no longer available. How can I modify the circuit to use available parts? I wonder if ...
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2answers
407 views

Should a rectifier or TVS diode be used as a flyback diode?

I'm trying to design a circuit for a relay similar to the following (except using SMT components): When I went to Mouser to try to find a suitable SMT diode to use in place of the 1N4001, I noticed ...
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2answers
4k 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 ...
2
votes
3answers
347 views

Is it possible to store flyback voltage in capacitors?

I recently put together a circuit that I use to control an electrical motor. I use an Arduino's PWM through darlington-pair transistors to control the speed of the motor. During construction of this ...
0
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1answer
190 views

Where to salvage inductors?

I need a toroidal inductor for my ZVS flyback driver. The value should be between 47uH to 200uH. It should be able to handle 6A. Where can I salvage them from?
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votes
3answers
374 views

NE555 Flyback Driver MOSFET failiure

simulate this circuit – Schematic created using CircuitLab I made this simple NE555 Flyback driver. I used a 9V Battery to power the NE555 and a 24V 6A power supply to power the flyback. ...
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2answers
445 views

Flyback diode forward voltage drop

In an ideal flyback diode selection, one would seek a diode which has very large peak forward current capacity (to handle voltage transients without burning out the diode), low forward voltage ...
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0answers
149 views

How to get better output out of flyback driver?

simulate this circuit – Schematic created using CircuitLab I used this circuit to power my flyback... I used an MJE3055T Power NPN and 10kOhm pot. The flyback is FKD15A001. I used the ...
0
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1answer
178 views

IC555 flyback driver troubleshooting

I made a flyback driver which just uses an astable 555 circuit to drive the flyback. The 4 and the 8 pins were connected to the positive rail. 7 pin was connected to the positive rail via a 1K ...
2
votes
1answer
394 views

H-Bridge freewheeling current

I'm building an H-Bridge to drive some motors I have around. I'd like to have a bridge that can be powered by different power sources, for example batteries or atx power supplies interchangeably. ...
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2answers
334 views

How does a flyback diode work?

In a previous question I posted to the exchange I asked for some instructions on trying to variable speed control a motor. Someone suggested utilizing PWM from my Arduino to open and close a ...
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2answers
537 views

What are the effective power limitations of the flyback converter topology, and why?

Looking at several different isolated converter topologies, flyback looks like it's the simplest at first glance. There's only one switch, so there's only one driver, which (all other things being ...
0
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1answer
1k views

Simulating a Flyback converter using Matlab / Simpowersystems, cannot get it to work, any tips?

I have created a flyback converter model using Simpowersystems in Simulink/Matlab. But it always gives me the wrong answer! I have simulated the same system using PLECS and Simscape/simulink and got ...
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4answers
6k views

Correct use of Flyback or Snubber diode across Motor or Transistor?

From seeing a few schematics where the flyback or snubber diode has been placed across the transistor C-E terminals (Right Configuration), instead of what I typically seen as the the flyback being ...
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3answers
471 views

BJT vs MOSFET for very low power flyback converter

I am currently working on a flyback design charging a capacitor in the nF range to 200V from an input voltage of around 1.5V. As the final circuit should be as small as possible, my component choices ...
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2answers
150 views

Electric vehicle power component selection help

I need your advice on high power device selection. I'm working with a similar application to this schematic, with the descriptions being in this forum. Without reading through the dozens of pages ...
2
votes
1answer
175 views

Recommended High Voltage Supply Circuit

Are there any circuit template I could look into if I want to achieve the following specification stated below: Input: 5VDC Output: 1kV, 0.5mA I was looking into the flyback convertor but I am not ...
1
vote
1answer
216 views

Transformer for variable output off-line boost flyback converter

I've built a flyback regulator that can produce 100-400V from mains, but -- due to limited off-the-shelf transformer options -- I'm pretty sure I'm not using the best transformer for the job (unless I ...
3
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1answer
504 views

The flyback diode and its applications

So in an application like this: The coil of the motor will, by Lenz's Law, induce a very large negative voltage across its terminals (without the diode in place). Would this voltage be very ...
5
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4answers
2k views

Why is flyback air gap needed for energy storage?

Why do so many sources say something along the lines "since a flyback transformer stores energy, an air gap is needed"? I have seen this reasoning in textbooks and app notes. I thought air gaps ...
0
votes
1answer
232 views

Building a decent 12V power supply from batteries

I'm currently building a flyback transformer. As you can see, the power supply is 12-15V, 3A. Up until now I've been using a 12VDC power supply from batteries. I guess I should have realized sooner ...
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2answers
654 views

Flyback transformer construction issues

Previous thread: Flyback transformer So, in short, I'm attempting to build a flyback transformer. The schematic I am using is this: And the flyback core looks like this: Upon recommendation ...
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3answers
129 views

Can a reed switch be used instead of a flyback diode?

Just wondering, a flyback diode is typically used to protect the circuit. Could the magnetic field generated by the flyback be captured to drive a reed switch and protect the circuit the same way a ...