Ferrite toroid Cores

General information about Ferrites

The information on this page is offered as a guide. It is based on manufactures specifications.

Type 1 :

Colour – Blue

These can be used from around 150 KHz to 3 Mhz

Common Sizes – 37-1 , 50-1, 68-1

Type 2:

Colour – Red

These can be used from around 200 KHz to 10 Mhz

Common Sizes – 25-2, 30-2, 37-2, 50-2, 68-2, 94-2, 106-2, 200-2, 300-2

Type 3:

Colour – Grey

These can be used from around 20 KHz to 1 Mhz

Common Sizes – 50-3,

Type 6:

Colour – Yellow

These can be used from 3 Mhz to 40 Mhz

Common Sizes – 25-6, 30-6, 37-6, 50-6, 68-6, 80-6, 94-6,

Type 31:

Colour – Black

These can be used from 0.5 to 30 Mhz in Unun’s/Baluns or 1 to 200 Mhz in low power transformers.

Common Sizes – 120-31, 240-31

Type 43 :

Colour – Black

These can be used between 500 KHz and 30 Mhz in Unun’s / Baluns’s or 5Mhz to 400 Mhz in low power transformers.

Common Sizes – 37-43, 50-43, 82-43, 140-43, 240-43

Type 61:

Colour – Black

These can be used from 20Mhz to 500 Mhz.

Common Sizes – 37-61, 82-61, 114-61, 240-61

While many manufacturers adhere to the above specifications, not all do. So just finding a certain colour might not mean its that type of Ferrite.

The common sizes are based on the types I have been able to find easily. Other types and sizes of ferrite toroid are manufactured but they can be difficult to find.

The given frequency ranges are a guide to the most efficient use. They will work outside this range but may be less efficient or become saturated.

 

 

 

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