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38 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 ...
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0answers
26 views

How would I create an oscillator for a rectified flyback? [on hold]

I created a spark gap of about 2 inches from a flyback transformer. The power source used is 19v and 2.15 amps of DC. http://youtu.be/cd3LdRC9njg *I changed the capacitor to .1µf because with a ...
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1answer
36 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 ...
6
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3answers
174 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
102 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
105 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
54 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
227 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
93 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
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1answer
64 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
34 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
94 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 ...
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1answer
72 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 ...
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1answer
62 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
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1answer
83 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 ...
0
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3answers
128 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
130 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
226 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
253 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 ...
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1answer
64 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
288 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
3k 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
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3answers
254 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 ...
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1answer
153 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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3answers
262 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
385 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
108 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 ...
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1answer
156 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
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1answer
325 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
263 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
390 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 ...
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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
4k 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
414 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
132 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 ...
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1answer
162 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 ...
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1answer
202 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 ...
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1answer
455 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 ...
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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 ...
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1answer
227 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
604 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
121 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 ...
5
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3answers
677 views

Solenoids causing Arduino to malfunction despite protection diode

simulate this circuit – Schematic created using CircuitLab I have an Arduino Mega that I'm attempting to control some solenoids and LEDs with. The LEDs are 3.3V, controlled through an ...
0
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1answer
988 views

Flyback transformer

Recently, I posted a question about a flyback transformer schematic I was having. If you didn't check the link, I was having problems with the frequency of the 555 timer as well as problems with ...
0
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3answers
562 views

Need a protection diode if only connected by common ground?

I have many solenoids running on 25VDC. Some are controlled by MOSFETs which are powered by a 5VDC circuit, and others are controlled by physical switches in the 25V lines. The 5V and 25V circuits ...
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2answers
618 views

Flyback transformer - ambiguous schematics and other issues

I'm currently using schematic for a flyback transformer. As you can see, there's a big problem - neither the schematic, nor the website describing it, give the value of the capacitor. It says ".01", ...
0
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3answers
192 views

Transformer for Flyback power supply

I am designing an isolated DC-DC converter with an input of 12V and an output of 5V@12A, at the moment, a flyback seems like the best option. I have read several books regarding the subject and I am ...
0
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1answer
105 views

Is a flyback supposed to have infinite resistance on the secondary (arc) coil?

Previously, I was able to get nice arcs with the 555 timer and irfp450 MOSFETS. When they died out I thought it was just the FETS but when I went through the proper test procedure for the FETS, I ...
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2answers
1k views

Getting Right parts and building ZVS flyback correctly

I recently built a 555 timer flyback driver. I used 2 IRFP450 MOSFET's in parallel to drive it and I got pretty good arcs. Something always seemed to fail, and I always was buying another 555 chip or ...
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1answer
614 views

Why high voltage from TV flyback shocks you without the need to complete a circuit?

Assuming the TV is plugged into an isolation transformer (although I think there is already a small transformer onboard), then ground is not part of the secondary side. Yet, high voltage from flyback ...