I have a Toroid Core listed here: LINK , i have T130-52 . I have all the values of the core from this sheet. Now i need to build an inductor out of this toroid. How do i determine which wire to wound, and how many turns would give me what inductance?


1 Answer 1


Look under \$A_L\$ to see the core's inductance factor, which is the expected inductance (in nanohenries) per turns squared.

\$A_L = \dfrac{L}{turns^2}\$

So, with some algebra:

\$L = A_L \cdot turns^2 \$

\$ turns = \sqrt{\dfrac{L}{A_L}}\$

As for the wire size, choose appropriately based on your expected current (which you haven't specified), the diameter of the wire and the available space on the core.

  • \$\begingroup\$ Thanks. Does the wire size/gauge thickness also effect the inductance? \$\endgroup\$
    – Sherby
    Commented Sep 22, 2013 at 23:24
  • 1
    \$\begingroup\$ Not really. A turn is a turn when it comes to inductance factor. How you wind the inductor influences things like stray capacitance and leakage inductance (if you have multiple windings). \$\endgroup\$ Commented Sep 22, 2013 at 23:58
  • \$\begingroup\$ I havent made inductors myself before. Is leaving some gap between the wires a good practice to counter the stray caps and inductances. Anything else i should keep in mind while making it? \$\endgroup\$
    – Sherby
    Commented Sep 23, 2013 at 0:01
  • 2
    \$\begingroup\$ Generally, uniformly spreading the wire around the toroid and keeping the turns as uniform as possible is a good practice. Try to keep things in a single layer if possible as well. Machines exist that wind turns onto toroids but doing it by hand is possible (with practice). \$\endgroup\$ Commented Sep 23, 2013 at 0:08

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