(Click image to enlarge) 

Here is an air core inductor coil (also known as a “choke”) that we picked up surplus:  It is 1.18 mH, with DCR = 0.90Ω.  It is most useful in speaker crossover or filter situations where a little resistance in the inductor is useful for damping or attenuation purposes.  It can fairly easily be modified to a lower value, by pulling off turns as needed, or we can do that for you, to a 1% tolerance.  We will measure mark exact value of the inductor on each unit, whether modified or not.

The winding is a “scatter wind”, with two areas of hot glue applied, one on each side, to keep the windings in place.  For very high end applications, users may wish to “pot” the inductor.  (If we get significant interest in this sort of enhancement, we will consider offering this part potted.)

Dimensions & Data:

O.D. (bobbin) = 2.13″

I.D. (bobbin)  = 1.04″

Ht. (bobbin) = 0.62″ (includes the slight ridges on the top and bottom.)

Inductance = 1.18 mH (nominal) @ 1000 Hz.

DC Resistance = 0.90Ω (at 1.18 mH)

Crossover frequency =  1078 Hz (assumes a 6 dB / octave low pass filter into an 8 ohm load.)

Wire = Std. insulated copper magnet wire.

Wire dia. = 0.0305″ (very close to 21 ga.)

Maximum recommended current = 4.5 amps rms (average continuous current).*

Bobbin Material = Nylon (we think).

Weight = 88 grams / 3.1 oz.  (Shipping weight will be a little higher.)

Price:  $4.00 ea.  Add $1.00 for custom modified values to 1% tolerance.   Limit 10 pcs. per order unless you have a special situation (Contact Us).

*The maximum current recommendation assumes open air flow around the inductor.  If you pack it or any other crossover or speaker component in under insulative material, you should derate it accordingly!  The same is true for sealed box systems operated at high power, which will elevate the temperature inside the enclosure considerably.