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TOROIDAL
IRON CORE INDUCTOR DESIGN
Powdered
Iron Toroidal Core Inductor Calculation.
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Calculation
to determine the number of turns required for a range of powdered iron
core toroids to achieve a particular inductance value.
L =
Inductance in uH
 =
Inductive index in uH per 100 turns as specified by the
manufacturer.
N =
Number of turns.
Example
The number of turns
required for a 12uH inductor if the
for
the selected powdered iron core is 49 (T-50-2).
|
AL
Value
|
|
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
|
|
T-16
|
145
|
61
|
55
|
44
|
22
|
n/a
|
19
|
13
|
8
|
8
|
3
|
|
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
|
|
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
|
Table of AL values for a
selection of powdered iron
core toroids.
|
Iron
Powder Magnetic Core Dimensions
|
|
Size
|
Colour
|
Dimensions
|
|
O.D.
|
I.D.
|
HEIGHT
|
|
in
|
mm
|
in
|
mm
|
in
|
mm
|
|
T-200-2
|
Red
|
2
|
50.80
|
1.25
|
31.75
|
0.55
|
13.97
|
|
T-94-2
|
Red
|
0.94
|
23.88
|
0.56
|
14.224
|
0.31
|
7.874
|
|
T-80-2
|
Red
|
0.8
|
20.32
|
0.5
|
12.7
|
0.25
|
6.35
|
|
T-68-2
|
Red
|
0.68
|
17.27
|
0.37
|
9.398
|
0.19
|
4.826
|
|
T-50-2
|
Red
|
0.5
|
12.70
|
0.3
|
7.62
|
0.19
|
4.826
|
|
T-37-2
|
Red
|
0.37
|
9.40
|
0.21
|
5.334
|
0.12
|
3.048
|
|
T-25-2
|
Red
|
0.25
|
6.35
|
0.12
|
3.048
|
0.09
|
2.286
|
|
T-12-2
|
Red
|
0.125
|
3.18
|
0.06
|
1.524
|
0.05
|
1.27
|
|
T-50-10
|
Black
|
0.5
|
12.70
|
0.3
|
7.62
|
0.19
|
4.826
|
|
T-37-10
|
Black
|
0.37
|
9.40
|
0.21
|
5.334
|
0.12
|
3.048
|
|
T-25-10
|
Black
|
0.25
|
6.35
|
0.12
|
3.048
|
0.09
|
2.286
|
|
T-12-10
|
Black
|
0.125
|
3.18
|
0.06
|
1.524
|
0.05
|
1.27
|
|
T-94-9
|
Yellow
|
0.94
|
23.88
|
0.56
|
14.224
|
0.31
|
7.874
|
Table of core dimensions
for a selection of powdered iron
core toroids.
|
Iron Powder
Magnetic Core Properties
|
|
Mix
|
Color
|
Material
|
μ
|
Temp
|
f
(MHz)
|
Uses
|
|
Stability
|
|
(ppm/°C)
|
|
26
|
Yellow/White
|
Hydrogen
Reduced
|
75
|
825
|
DC
-10MHz
|
EMI
filters, DC chokes
|
|
3
|
Gray
|
Carbonyl
HP
|
35
|
370
|
0.05
- 0.500MHz
|
Exc.
stability, good Q at low freq.
|
|
15
|
Red/White
|
Carbonyl
GS6
|
25
|
190
|
0.10
- 20MHz
|
Exc.
stability, good Q
|
|
1
|
Blue
|
Carbonyl
C
|
20
|
280
|
0.50
- 50MHz
|
Exc.
stability, good Q at low freq.
|
|
2
|
Red
|
Carbonyl
E
|
10
|
95
|
2
- 30MHz
|
High
Q
|
|
7
|
White
|
Carbonyl
TH
|
9
|
30
|
3
- 35MHz
|
Similar
to mix 2 and mix 6, exc. temp stability
|
|
6
|
Yellow
|
Carbonyl
SF
|
8
|
35
|
10
- 50MHz
|
Very
good Q and temp. stability for 20-50 MHz
|
|
10
|
Black
|
Powdered
Iron W
|
6
|
150
|
30
- 1000MHz
|
Good
Q and stability for 40-100 MHz
|
|
12
|
Green/White
|
Synthetic
Oxide
|
4
|
170
|
50
- 2000MHz
|
Good
Q, moderate temp. stability
|
|
17
|
Blue/Yellow
|
Carbonyl
|
4
|
50
|
40
- 1800MHz
|
Similar
to mix 12, better temp. stability, Q drops about 10% above 50
MHz, 20% above 100 MHz
|
|
0
|
Tan
|
Phenolic
|
1
|
0
|
100
- 3000MHz
|
L
varies greatly with winding technique
|
Table of core properties
for powdered iron
core.
Iron Powder Core Inductor Design
Software: http://www.micrometals.com/material/IPIDsgnSoftwaretxt.html
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last revised 05 May, 2025
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