Toroid notes:
Apart from the physical dimensions of a toroid (outside and inside diameter, thickness) there is a value given for each particular core size and material, which is usually called the AL value, and is the manufacturers inductance index for the core. Manufacturers data for iron powder and ferrite cores are in the data tables and show all the required information. The AL figure for iron powder cores is given as uH/100 turns, but for ferrite cores it is quoted as mH/1000 turns. Note that many other manufacturers quote AL as nH/t2 for both types of material. The conversion from uH/100 turns to nH/t2 gives a result which is divided by 10. The relevent AL value is used in many calculations involving cores. One of the most common uses is to calculate the turns required to produce a given value of inductance on a particular core, as shown below:
Iron powder: turns = 100 ((desired L/AL) 0.5) (where L in uH) Some examples
Ferrite: turns = 1000 ((desired L/AL) 0.5) (where L in mH) Some examples
Note: doubling the turns produces four times the inductance.

IRON POWDER TOROIDS - AL Values **

  Material ( )
Core Size 26 3 15 1 2 6 10 12/17 0
 
T-12-( ) * 60 50 48 20 17 12 7.5 2.4
T-16-( ) 145 61 55 44 22 19 13 8 3
T-20-( ) 185 76 65 52 25 22 16 10 3.5
T-25-( ) 245 100 85 70 34 27 19 12 4.5
T-30-( ) 335 140 93 85 43 36 25 16 6
T-37-( ) 285 120 90 80 40 30 25 15 4.9
T-44-( ) 370 180 160 105 52 42 33 18.5 6.5
T-50-( ) 330 175 135 100 49 40 31 18 6.4
T-68-( ) 435 195 180 115 57 47 32 21 7.5
T-80-( ) 460 180 170 115 55 45 32 22 8.5
T-94-( ) 600 248 200 160 84 70 58 * 10.6
T-106-( ) 930 450 345 325 135 116 * * 19
T-130-( ) 810 350 250 200 110 96 * * 15
T-157-( ) 1000 420 * 320 140 115 * * *
T-184-( ) 1690 720 * 500 240 195 * * *
T-200-( ) 920 425 * 250 120 100 * * *
T-200A-( ) 1600 * * * 218 * * * *
* size not available in this material
** AL= µH/100 turns

FERRITE TOROIDS - ALValues **
  Material ( )
Core Size 43 61 63 67 68 75 77 F J
 
FT-23-( ) 188 248 * 7.8 4.0 990 356 * *
FT-37-( ) 420 55.3 * 19.7 8.8 2110 884 * *
FT-50-( ) 523 68.0 * 22.0 11.0 * 990 * 2750
FT-50A-( ) 570 75.0 * 24.0 12.0 * 1080 * 2990
FT-50B-( ) 1140 150.0 * 48.0 24.0 * 2160 * *
FT-82-( ) 557 73.3 * 22.4 11.7 * 1060 * *
FT-87-( ) * * * * * * * * 3020
FT-87A-( ) * * * * * * * 3700 6040
FT-114-( ) 603 79.3 * 25.4 12.7 * 1270 1902 3170
FT-114A-( ) * 146.0 * * * * 2340 * *
FT-140-( ) 952 140.0 * 45.0 * * 2340 * *
FT-140A-( ) * * * * * * * * 6736
FT-150-( ) * * * * * * * 2640 4400
FT-150A-( ) * * * * * * * 5020 8370
FT-193-( ) * * * * * * * 3640 6065
FT-193A-( ) * * * * * * * 4460 7435
FT-240-( ) 1240 173.0 53.0 53.0 * * 3130 * 6845
* size not available in this material
** AL = mH/1000 turns

IRON POWDER MATERIAL PROPERTIES
Material Colour Permeability
(µi)		 Temp. Coeff. 1
(+ppm/C)		 Range for Best Q
(MHz)
 
#262 yellow/white 75 822 0 - 1.0
 
#3 gray/clear 35 370 0.02 - 1.0
 
#15 red/white 25 190 0.15 - 3.0
 
#1 blue/clear 20 280 0.15 - 3.0
 
#2 red/clear 10 95 0.25 - 10
 
#6 yellow/clear 8.5 35 3 - 40
 
#10 black/clear 6.0 150 15 - 100
 
#12 green/white 4.0 1703 30 - 250
 
#17 blue/yellow 4.0 50 20 - 200
 
#0 tan/tan 1.0 0 50 - 350

  1. Value averaged from -55 to +125°C.

  2. Mainly used for dc chokes, differential-mode chokes, power factor correction inductors, continuous-mode flyback inductors, light dimmer chokes and other EMI/RFI applications.

  3. Non-linear. #17 has stable temp coeff., but provides about 10% lower Q than #12.

FERRITE MATERIAL PROPERTIES
  Material
  43 61 64 67 68 73 77 F J/75
 
Initial Perm. 850 125 250 40 20 2500 2000 3000 5000
 
Max. Perm. 3000 450 375 125 40 4000 6000 4300 9500
 
Max. Flux Density
@ 10oer. (gauss)
 2750 2350 2200 3000 2000 4000 4600 4700 4300
 
Residual Flux
Density (gauss)		 1200 1200 1100 1000 1000 1000 1150 900 500
 
Vol. Resistivity
(ohms/cm)		 1x105 1x108 1x108 1x107 1x107 1x102 1x102 1x102 1x102
 
Temp. Coeff. (%/C)
-20 to 70 °C		 1 0.15 0.15 0.13 0.06 0.8 0.25 0.25 0.4
 
Loss Factor
(x 10-6)		 120@
1MHz		 32@
2.5MHz		 100@
2.5MHz		 150@
50MHz		 400@
100MHz		 7.0@
0.1MHz		 4.5@
0.1MHz		 4.0@
0.1MHz		 15@
0.1MHz
 
Coercive Force
(Oersteds)		 0.3 1.6 1.4 3 10 0.18 0.22 0.2 0.1
 
Curie Temp. (°C) 130 350 210 500 500 160 200 250 140
 
Resonant Circ.
Freq. (MHz)		 .01-1 .2-10 0.05-4 10-80 80-180 .001-1 .001-2 .001-1 .001-1
 
Wideband Circ.
Freq. (MHz) *		 1-50 10-200 50-500 50-500 200-1000 .2-15 .5-30 .5-30 1-15
 
Noise Attenuation
MHz		 20-400 >200 >200 >1000 >10000 1-40 1-40 1-20 0.5-10

* Based on low power, small core applications. Listed frequencies will be lower with high power.



IRON POWDER CORE SIZE vs WIRE SIZE/TURNS ( Single layer winding )

Core Size Wire Gauge (Awg)
  14 16 18 20 22 24 26 28 30 32 34 36
T-12 0 1 1 1 2 4 5 8 11 15 21 29
T-16 1 1 1 3 3 5 8 11 16 21 29 38
T-25 1 3 4 5 7 11 15 21 28 37 48 62
T-37 5 7 9 12 17 23 31 41 53 67 87 110
T-50 8 11 16 21 28 37 49 63 81 103 131 166
T-68 12 15 21 28 36 47 61 79 101 127 162 205
T-80 17 23 30 39 51 66 84 108 137 172 219 276
T-94 20 27 35 45 58 75 96 123 156 195 248 313
T-106 20 27 35 45 58 75 96 123 156 195 248 313
T-130 30 40 51 66 83 107 137 173 220 275 348 439
T-157 38 50 64 82 104 132 168 213 270 336 426 536
T-184 38 50 64 82 104 132 168 213 270 336 426 536
T-200 53 68 86 109 139 176 223 282 357 445 562 707

FERRITE CORE SIZE vs WIRE SIZE/TURNS ( Single layer winding)

Core Size Wire Gauge (Awg)
  14 16 18 20 22 24 26 28 30 32 34 36
FT-23 0 0 2 4 7 11 15 21 28 37 48 62
FT-37 2 4 7 11 15 21 28 36 48 61 79 100
FT-50 7 10 14 19 26 34 45 58 75 95 121 154
FT-50A 8 13 19 22 30 39 51 66 84 106 135 171
FT-50B 8 13 19 22 30 39 51 65 84 106 135 171
FT-82 18 22 32 41 53 69 88 112 143 180 228 288
FT-87 19 25 34 43 56 72 92 118 150 188 239 239
FT-114 29 38 49 63 80 100 131 166 211 263 334 334
FT-140 36 42 60 77 97 125 158 201 255 318 403 403
FT-150 29 38 49 63 80 100 131 166 211 263 334 334
FT-193 53 68 86 109 139 176 223 282 357 445 562 562
FT-240 60 77 98 123 156 198 250 317 400 499 631 631

IRON POWDER TOROIDS - PHYSICAL DIMENSIONS

Core Number O.D.
(inches)		 I.D.
(inches)		 Hgt
(inches)
 
T-12-( ) .125 .062 .050
T-16-( ) .160 .078 .060
T-20-( ) .200 .088 .070
T-25-( ) .255 .120 .096
T-30-( ) .307 .151 .128
T-37-( ) .375 .205 .128
T-44-( ) .440 .229 .159
T-50-( ) .500 .303 .190
T-68-( ) .690 .370 .190
T-80-( ) .795 .495 .250
T-94-( ) .942 .560 .312
T-106-( ) 1.060 .570 .437
T-130-( ) 1.300 .780 .437
T-157-( ) 1.570 .950 .570
T-184-( ) 1.840 .950 .710
T-200-( ) 2.000 1.250 .550
T-200A-( ) 2.000 1.250 1.000

FERRITE TOROIDS - PHYSICAL DIMENSIONS

Core Number O.D.
(inches)		 I.D.
(inches)		 Hgt
(inches)
FT-23-( ) .230 .120 .060
FT-37-( ) .375 .187 .125
FT-50-( ) .500 .281 .188
FT-50A-( ) .500 .312 .250
FT-50B-( ) .500 .312 .500
FT-82-( ) .825 .516 .250
FT-87-( ) .870 .540 .250
FT-87A-( ) .870 .540 .500
FT-114-( ) 1.142 .750 .295
FT-114A-( ) 1.142 .750 .545
FT-140-( ) 1.400 .900 .500
FT-140A-( ) 1.400 .900 .590
FT-150-( ) 1.500 .750 .250
FT-150A-( ) 1.500 .750 .500
FT-193-( ) 1.932 1.250 .625
FT-193A-( ) 1.932 1.250 .750
FT-240-( ) 2.400 1.400 .500