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I would like to build a flyback and I've tried simulating my circuit in LTSPICE, in which I coupled a PCH-45X-824 inductor (820µH, 986mA pk) with a 744139 WE-SI inductor (1.124mH, 3A pk).

It works well and provided the output I wanted so I was wondering if I can place the two inductors in parallel to each other on the breadboard/PCB and will it work the same way it did in the simulations?

Thanks!

Edit: I have a 555 pwm to control the switching speed of the mosfet which will control the voltage and duty cycle of the output

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    \$\begingroup\$ How do you intend on coupling them? \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jun 15, 2016 at 0:47
  • \$\begingroup\$ Expect it to work much more poorly than simulation. \$\endgroup\$
    – Matt Young
    Commented Jun 15, 2016 at 0:47
  • \$\begingroup\$ For a flyback, both inductors should be wound on the same core. \$\endgroup\$
    – Nick Alexeev
    Commented Jun 15, 2016 at 0:47
  • \$\begingroup\$ add the coupling statement from your SPICE file, the K statement, to your post so that you, and we, can see what you're actually simulating. Then you can be advised on how much physical coupling on the PCB is required to match the coupling the simulation uses. Hint, it will probably involve both inductors on the same core, as the other responders have suggested. \$\endgroup\$
    – Neil_UK
    Commented Jun 15, 2016 at 4:52
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    \$\begingroup\$ @IgnacioVazquez-Abrams Initially I thought by placing them in parallel it will be enough to couple them, just realised that they have to be sharing the same core, my mistake. Thanks \$\endgroup\$
    – John Doe
    Commented Jun 15, 2016 at 6:36

2 Answers 2

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What does "coupled" mean in your simulation? Your simulation should have shown ZERO output. You need a transformer (with both primary and secondary windings on the SAME core) to implement the circuit you have shown.

You must have simulated a transformer. And that is what you will need to implement the circuit.

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  • \$\begingroup\$ Thanks for the answer, so does it mean that I have to get a ferrite core and calculate the windings for this inductance value to implement this? \$\endgroup\$
    – John Doe
    Commented Jun 15, 2016 at 1:58
  • \$\begingroup\$ Yes, the inductors have to be magnetically coupled, so they have to share a core as other users have already told you. \$\endgroup\$
    – Claudio Avi Chami
    Commented Jun 15, 2016 at 3:54
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Putting two inductors side-by-side (assuming a distance like 1-10 cm between them ) couples these two inductors through the air. However, this coupling will be very poor since air itself is a poor magnetic material, and your circuit will not work. In order to increase the coupling you need a ferromagnetic environment. And this can be achieved by winding these two inductors of yours on the same iron core.

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