Ben Bradley wrote:
In
sci.electronics.design,sci.electronics.repair,sci. electronics.components,alt.binaries.schematics.ele ctronic,
"Watson A.Name - \"Watt Sun, the Dark Remover\""
wrote:


"Reg Edwards" wrote in message
...


But why would you want to know the number of turns if the coil is
already wound!
If I don't know the number of turns to begin with, do you expect me to
UNwind the coil to find the number of turns?


You didn't answer the question. WHY do you want to find the number
of turns?

Okay, I'll answer for you. Reverse engineering. You want to make
one or more coils exactly like it. Of course, not only do you need the

If I want to know what the core material is, then I need to know how
many turns it has, given a known inductance. But even if I decide to
buy rather than build one, I will have to determine the number of turns
so I can buy a coil like it, with approximately the same number of
turns. Like you said below, it might be cheaper to buy one.

number of turns (and the exact layout of the turns), you also need to
know exactly what the magnetic core material is - you can either ask
the manufacturer (of either the core or the coil), or measure its
physical size and test all its magnetic properties.

Can't ask the manufacturere if one doesn't know who made the coil to
begin with.

An inductor is one of the easier components to make in the "home
laboratory" and it's good to know you can look up formulas and stuff
(the ARRL handbook, at least older editions, has some useful coolbook
formulas for cylindrical coils) for those times when you need it ASAP
and can't wait for overnight delivery, but otherwise it's still
cheaper to buy than to build.



[snip]