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Toroids: Powdered Iron

Use the table below to calculate inductance and number of turns per the following formulas.

Toroidal inductor equation formula

Where:

L = inductance in µH

A_L = µH per 100 turns

N = number of full turns

A_L Values
	Mix Type
Size	26	3	15	1	2	7	6	10	12	17	0
T-12	n/a	60	50	48	20	18	17	12	7.5	7.5	3.0
T-16	145	61	55	44	22	n/a	19	13	8.0	8.0	3.0
T-20	180	76	55	52	27	24	22	16	10	10	3.5
T-25	235	100	85	70	34	29	27	19	12	12	4.5
T-30	325	140	93	85	43	37	36	25	16	16	6.0
T-37	275	120	90	80	40	32	30	25	15	15	4.9
T-44	360	180	160	105	52	46	42	33	18.5	18.5	6.5
T-50	320	175	135	100	49	43	40	31	18	18	6.4
T-68	420	195	180	115	57	52	47	32	21	21	7.5
T-80	450	180	170	115	55	50	45	32	22	22	8.5
T-94	590	248	200	160	84	n/a	70	58	32	n/a	10.6
T-106	900	450	345	325	135	133	116	n/a	n/a	n/a	19
T-130	785	3350	250	200	110	103	96	n/a	n/a	n/a	15
T-157	870	420	360	320	140	n/a	115	n/a	n/a	n/a	n/a
T-184	1640	720	n/a	500	240	n/a	195	n/a	n/a	n/a	n/a
T-200	895	425	n/a	250	120	105	100	n/a	n/a	n/a	n/a

Iron Powder Magnetic Core Properties
Mix	Color	Material	μ	Temp Stability (ppm/°C)	f (MHz)	Uses
26	Yellow/White	Hydrogen Reduced	75	825	DC -1	EMI filters, DC chokes
3	Gray	Carbonyl HP	35	370	0.05 - 0.50	Exc. stability, good Q at low freq.
15	Red/White	Carbonyl GS6	25	190	0.10 - 2	Exc. stability, good Q
1	Blue	Carbonyl C	20	280	0.50 - 5	Exc. stability, good Q at low freq.
2	Red	Carbonyl E	10	95	2 -30	High Q
7	White	Carbonyl TH	9	30	3 - 35	Similar to mix 2 and mix 6, exc. temp stability
6	Yellow	Carbonyl SF	8	35	10 -50	Very good Q and temp. stability for 20-50 MHz
10	Black	Powdered Iron W	6	150	30 - 100	Good Q and stability for 40-100 MHz
12	Green/White	Synthetic Oxide	4	170	50 - 200	Good Q, moderate temp. stability
17	Blue/Yellow	Carbonyl	4	50	40 - 180	Similar to mix 12, better temp. stability, Q drops about 10% above 50 MHz, 20% above 100 MHz
0	Tan	Phenolic	1	0	100 - 300	L varies greatly with winding technique

Iron Powder Magnetic Core Dimensions
Size	Color	Dimensions (in)
Size	Color	O.D.	I.D.	Height
T-200-2	Red	2.00	1.25	0.55
T-94-2	Red	0.94	0.56	0.31
T-80-2	Red	0.80	0.50	0.25
T-68-2	Red	0.68	0.37	0.19
T-50-2	Red	0.50	0.30	0.19
T-37-2	Red	0.37	0.21	0.12
T-25-2	Red	0.25	0.12	0.09
T-12-2	Red	0.125	0.06	0.05
T-50-10	Black	0.50	0.30	0.19
T-37-10	Black	0.37	0.21	0.12
T-25-10	Black	0.25	0.12	0.09
T-12-10	Black	0.125	0.06	0.05
T-94-9	Yellow	0.94	0.56	0.31
T-80-6	Yellow	0.80	0.50	0.25
T-68-6	Yellow	0.68	0.37	0.19
T-50-6	Yellow	0.50	0.30	0.19
T-26-6	Yellow	0.25	0.12	0.09
T-12-6	Yellow	0.125	0.06	0.05

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