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6
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3answers
273 views

Can a Zener diode that protects a switch against inductance when the switch opens, affect turn on speed of the valve while 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 ...
1
vote
1answer
46 views

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

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 ...
0
votes
3answers
48 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 ...
0
votes
0answers
29 views

Using a ballast to power a flyback transformer

I know there are many ways to power a flyback transformer. For example you can build a driver using a 2N055 transistor, a 555 or a ZVS. However I discovered that you can also use a ballast, as seen ...
0
votes
1answer
49 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.
1
vote
1answer
87 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 ...
0
votes
0answers
23 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 ...
0
votes
2answers
191 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
80 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 ...
1
vote
1answer
63 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 ...
2
votes
2answers
89 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 ...
0
votes
0answers
43 views

Output Diode Snubber in Flyback Converter

I just completed making 48W flyback using TOP224. It is a fairly old Controller as well as its old design book. I looked at some of their modern ICs and design books and found out some significant ...
0
votes
1answer
43 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 ...
1
vote
2answers
90 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 ...
0
votes
3answers
118 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. ...
0
votes
1answer
65 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 ...
2
votes
4answers
97 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 ...
1
vote
4answers
119 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 ...
1
vote
2answers
200 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
88 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
votes
1answer
116 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 ...
0
votes
0answers
84 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
votes
1answer
140 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
votes
3answers
320 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
votes
1answer
112 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. ...
1
vote
0answers
144 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 ...
0
votes
0answers
152 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
4
votes
2answers
326 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 ...
0
votes
2answers
112 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
87 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 ...
0
votes
1answer
67 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
vote
1answer
145 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
votes
1answer
103 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
votes
1answer
90 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
106 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
votes
3answers
156 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 ...
1
vote
2answers
231 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
votes
1answer
382 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: ...
1
vote
2answers
375 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
72 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 ...
1
vote
2answers
532 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 ...
7
votes
2answers
7k 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
444 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
votes
1answer
215 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?
2
votes
3answers
475 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. ...
5
votes
2answers
508 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 ...
0
votes
1answer
202 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
535 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. ...
2
votes
2answers
396 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 ...
4
votes
2answers
685 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 ...