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Re: scoped coils



Original poster: "Chris Swinson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <exxos-at-cps-games.co.uk>

Hi Terry,

> Normally, I would think the fields around the coil would be very sensitive
> to your have and would easily show the effects no matter what kind of wire
> and such was used.  the plastic wire coil really "should" be just as
sensitive.
>
> I assume you had them both hooked up to the scope and all exactly the
same.
>  My best guess is that something was not right with the test.  But other
> than that I am stumped...  Here are diagrams of the usual fields around
coils:


I will say that the larger coil is 90"high by 6.3" wide, uses 1.5^2mm wire
( 10amp multi stranded ). This coil I worked to 360khz....  The other coil
on test was also worked to 360khz. This one was on 4.3" dia form, about 20"
high with 0.315mm magnet wire.

They were both hooked in the same way. I tested them in the following way...
I take a rectifier and connect one AC input to the signal generator, the
other to the coils on test. The + and - then goto a DMM on MA range. The
scope is placed on the + side.

This results in when resonance is found the DMM current will go up to about
1ma. This in effect shorts out and the wave on the scope drops in voltage.
The higher the reading on the DMM the better it is in tune. I can also work
this by the scope in the lowest amplitude I can get.

What makes it a little odd is both coils give about the same MA reading, I
think the larger coil actually gave a little more reading. I don't know what
this means really but I only use for a indication of finding tune points.
As far as I can tell on the scope and DMM the coils are identical! as many
already probably know, you can also find other tune points on coils. If say
the best tune point is 200khz at 1ma then you could say find one at 350khz
at 0.7ma, maybe 500khz 0.4ma etc. Interesting stuff!

Chris