Is colour significant on toroids salvaged from scrap motherboards?
They're often pale blue or yellow - I think I've seen red ones too.
There's no standardization for the color coding of toroids.
Decades ago, there was a certain consistency in hobby circles, because
virtually all toroids that got to hobbyists were from the same source,
and interestingly, that common source was not a manufacturer but a small
business that had set out to be the middleman, since the manufacturers
weren't wanting to sell in small quantities.
Then, toroids became a lot more common. Originally they'd only be seen
in non-consumer radio equipment, but eventually they became common
there (albeit just a few toroids per unit), likely dwarfing the numbers
used for non-consumer radio equipment.
Once that started happening, there was all kinds of opportunity to find
toroids at the surplus store, or in consumer electronics that begged to
be reused. But, without any information about who made the core, the
color coding meant nothing.
If it's in equipment, at least the context will provide some information
(and most of the time, it will be low frequency use, mostly power
supplies). A blank toroid at the surplus store doesn't offer such
information.
One generally has to wind a coil on the toroid, do some measurements
and then calculations with the results. The more detail you need,
the more effort has to be put in the testing. And then likely
you could have gotten an identifiable toroid direct from some company
that wouldn't have cost that much.
Michael
