Toroid Inductance/Reference Chart ~ by David Smith G4COE

Toroid Inductance Chart

                                                                           David Smith G4COE

To save a little time from calculating and experimenting when winding toroid cores here a chart of the most commonly used cores, simply pick the inductance required and read the required number of turns for the selected core. To keep things easy we’ll stick to three most common cores, T37, T50 and T68 and we’ll use the  -2 and 6 mix, these figures are for single layer windings only, and the windings should cover the entire core evenly.

Turns - Inductance in µH

                

Turns Red T37-2 Yellow T37-6 Red  T50-2 Yellow  T50-6 Red T68-2 Yellow   T68-6 1 .004 .003 .005 .004 .006 .005 2 .016 .012 .020 .016 .023 .019 3 .036 .027 .044 .036 .051 .042 4 .064 .048 .078 .064 .091 .075 5 .100 .075 .120 .100 .140 0.12 6 .140 .110 .180 .140 .210 0.17 7 .196 .150 .240 .196 .280 0.23 8 .256 .190 .310 .256 .360 0.30 9 .324 .240 .400 .324 .460 0.38 10 .400 .300 .490 .400 .750 0.47 11 .484 .360 .590 .484 .690 0.57 12 .576 .430 .710 .576 .820 0.68 13 .676 .500 .830 .676 .960 0.79 14 .784 .590 .960 .784 1.10 0.92 15 .900 .680 1.10 .900 1.30 1.10 16 1.02 .770 1.30 1.02 1.50 1.20 17 1.16 .870 1.40 1.16 1.60 1.40 18 1.30 .970 1.60 1.30 1.80 1.50 19 1.40 1.10 1.80 1.40 2.10 1.70 20 1.60 1.20 2.00 1.60 2.30 1.90 21 1.80 1.30 2.20 1.80 2.50 2.10 22 1.90 1.50 2.40 1.90 2.80 2.30 23 2.10 1.60 2.60 2.10 3.00 2.50 24 2.30 1.70 3.10 2.30 3.30 2.70 25 2.50 1.90 3.10 2.50 3.60 3.40		Turns	Red T37-2	Yellow T37-6	Red  T50-2	Yellow  T50-6	Red T68-2	Yellow   T68-6
		26	2.70	2.00	3.30	2.70	3.90	3.20
		27	2.90	2.20	3.60	2.90	4.20	3.40
		28	3.10	2.40	3.80	3.10	4.50	3.70
		29	3.40	2.50	4.10	3.40	4.80	4.00
		30	3.60	2.70	4.40	3.60	5.10	4.20
		31	3.80	2.90	4.70	3.80	5.50	4.50
		32	4.10	3.10	5.00	4.10	5.80	4.80
		33	4.40	3.30	5.30	4.40	6.20	5.10
		34	4.60	3.50	5.70	4.60	6.60	5.40
		35			6.00	4.90	7.00	5.80
		36			6.40	5.20	7.40	6.10
		37			6.70	5.50	7.80	6.40
		38			7.10	5.80	8.20	6.80
		39			7.50	6.10	8.70	7.10
		40			7.80	6.40	9.10	7.50
		41			8.20	6.70	9.60	7.90
		42			8.60	7.10	10.0	8.30
		43			9.10	7.40	11.0	8.70
		44			9.50	7.70	11.0	9.10
		45			9.90	7.90	12.0	9.50
		46			10.0	8.50	12.0	9.90
		47			11.0	8.80	13.0	10.0
		48			11.0	9.20	13.0	11.0
		49			12.0	9.60	14.0	11.0
		50			12.0	10.0	14.0	12.0

For those interested in equations (√ L uH / AL value) x 100 will give us the turns required. To find the inductance of a pre-wound core, L uH  =  (turns/100)2  x AL value  of the core.  

 

This list could be expanded to cover many cores and greater winding ranges but would probably many pages of Sprat, this being pointless because many would not be used generally and any inductances greater than the range given above could be calculated with the above formula.   

Title:      Toroid Inductance Chart.                                                                           Author:  David Smith G4COE Page 1 of 2 GQRP Club Datasheet

Inductance in µH - Turns

                

µH Red T37-2 Yellow T37-6 Red  T50-2 Yellow  T50-6 Red T68-2 Yellow   T68-6 1 16 18 14 15 13 15 2 22 26 20 21 19 21 3 27 31 25 25 23 25 4 32 36 28 29 26 29 5 35 41 32 33 30 33 6 39 45 35 36 32 36 7 42 48 38 39 35 39 8 45 52 40 42 37 41 9 47 55 43 44 40 44 10 50 58 45 47 42 46 11 52 60 47 49 44 48 12 55 63 49 51 46 51 13 57 66 51 53 48 53 14 59 68 53 55 50 55 15 61 71 55 57 51 56 16 63 73 57 59 53 58 17 65 75 59 61 55 60 18 67 77 61 62 56 62 19 69 79 62 64 58 64 20 71 81 64 66 59 65 21 65 67 61 67 22 67 69 62 68 23 68 71 64 70 24 70 72 65 71 25 71 74 66 73

µH Red T37-2 Yellow T37-6 Red  T50-2 Yellow  T50-6 Red T68-2 Yellow   T68-6 26 73 75 68 74 27 74 77 69 76 28 76 78 70 77 29 77 79 71 79 30 78 80 73 80 31 79 82 74 81 32 80 83 75 83 33 82 85 76 84 34 83 86 77 85 35 84 87 78 86 36 86 88 79 88 37 87 89 80 89 38 88 91 82 90 39 89 92 83 91 40 90 93 84 92 41 91 94 85 93 42 92 96 86 95 43 94 97 87 96 44 95 98 88 97 45 96 99 89 98 46 97 100 90 99 47 98 101 91 100 48 99 102 92 101 49 100 103 93 102 50 101 104 94 103

Title:      Toroid Inductance Chart.                                                                           Author:  David Smith G4COE Page 2 of 2 GQRP Club Datasheet

Special thanks to G4COE David Smith and the GQRP Club for creating such a complete reference for us to use! I nore my page had anything to do with this reference other than converting it into a text format to make it searchable instead of just a PDF download.  IF you copy and paste it into a text file it should retain the correct format for your use.

The actual site can be found here www.gqrp.com/toroid_inductance_chart.pdf