# Antena that can sense thermal Radiation from human body

M

#### MassiveProng

Jan 1, 1970
0
most of his posts about magnetics are flat wrong.

You're an idiot. My remarks about gapping switcher transformers is
correct. We aren't talking about millimeter gaps here. More like nil
gaps. They have their function, and you would be wise to learn what
that function is.
However he has posted some useful stuff about HV windings.

The most common mistake made by folks experimenting with small
scale, high ratio step up, high turns count HV transformers are
placing too many turns in a given secondary segment, allowing a breech
through the insulation of the mag wire. Even the best double thick,
high temp mag wire is only good for about 300 turns per segment.

If one is not using a multi-segmented bobbin, one should place
layers of tape between a certain number of turns, and another "set" of
turns to keep the lowest voltage turn(s) away from turns that are at a
much higher voltage.

Volts per turn can be calculated to give the builder an idea of
where to "layerize" his turns or step to the next bobbin segment.

This is why a lot of Tesla coil builders space wind their stack
coil. Depends on how well they have designed it though, really.

A good double strength mag wire, and even varnishing of the finished
stack is always a good practice (several coats). I know this, and I
have yet to build one.

I will though. I'll use it to reproduce myself (ala prestige) and
send my double over their to whoop up on your lack of gapped core
knowledge. Slap ya right in the face. Tee Hee Hee!

T

#### Terry Given

Jan 1, 1970
0
MassiveProng said:
You're an idiot. My remarks about gapping switcher transformers is
correct. We aren't talking about millimeter gaps here. More like nil
gaps. They have their function, and you would be wise to learn what
that function is.

anyone who puts a gap in a buck-derived transformer should be slapped
silly. Its a BAD idea, because either:

1) they have no clue*, or

2) are using a lousy control methodology that is susceptible to
staircase saturation etc. There is a plethora (plague more like) of such
"designs" out there, and all suck c.f. Current Mode Control (CMC). At
worst, CMC is only slightly better than Voltage-MC (if it has input
feed-forward etc), for a few topologies. for all other topologies it is
a lot better.

* OK, I can elaborate here. they may have done something real stupid,
like forget that peak flux will saturate, but p-p flux is OK, except
when you first turn it on (CMC cures this too).

or they may have organised for too much flux, period. eg using Bsat(20C)
c.f. Bsat(100C), and discovering when it gets hot they explode. or just
using > Bsat(20C).

or they may simply think a low Lmag is a good thing (its not).

all of these things happen (I've seen them all), and all are indicative
of a lack of understanding. I often use toroids for buck-derived
converters - precisely because there is no gap. Big ones, too.

of course for any boost-derived converter, its a coupled inductor, and
the gap is a fundamental aspect of the design.
The most common mistake made by folks experimenting with small
scale, high ratio step up, high turns count HV transformers are
placing too many turns in a given secondary segment, allowing a breech
through the insulation of the mag wire. Even the best double thick,
high temp mag wire is only good for about 300 turns per segment.

dont you mean volts?
If one is not using a multi-segmented bobbin, one should place
layers of tape between a certain number of turns, and another "set" of
turns to keep the lowest voltage turn(s) away from turns that are at a
much higher voltage.

Volts per turn can be calculated to give the builder an idea of
where to "layerize" his turns or step to the next bobbin segment.

This is why a lot of Tesla coil builders space wind their stack
coil. Depends on how well they have designed it though, really.

A good double strength mag wire, and even varnishing of the finished
stack is always a good practice (several coats). I know this, and I
have yet to build one.

see.

there are some nice triple-dipped polyamide-imide magnet wires
available, and of course TIW is great.
I will though. I'll use it to reproduce myself (ala prestige) and
send my double over their to whoop up on your lack of gapped core
knowledge. Slap ya right in the face. Tee Hee Hee!

yeah right. I'll happily pit my off-the-cuff (sans calculator) magnetics
design skills against yours any day, loser buys the beer & pizza. But I
wont challenge you to a game of pool, as I'd probably lose.

Cheers
Terry

M

#### MassiveProng

Jan 1, 1970
0
dont you mean volts?

If your volts per turn are what they should be, the 300 turns per
segment come out about right. In some cases, it could be half that,
but not usually.

T

#### Terry Given

Jan 1, 1970
0
MassiveProng said:
If your volts per turn are what they should be, the 300 turns per
segment come out about right. In some cases, it could be half that,
but not usually.

OK, but doesnt that depend rather strongly on the shape of the segment,
and of course the size of the core - eg a very large core so many V/T
requiring correspondingly fewer turns, or a narrow yet deep segment, so
the final turn is a long way away from the start turn.

Cheers
Terry

M

#### MassiveProng

Jan 1, 1970
0
OK, but doesnt that depend rather strongly on the shape of the segment,
and of course the size of the core - eg a very large core so many V/T
requiring correspondingly fewer turns, or a narrow yet deep segment, so
the final turn is a long way away from the start turn.

Scatter winding is bad if there are too many turns because you don't
know what proximities are involved, and most folks don't vacuum
varnish on small scale switcher magnetics. So the depth of a segment
doesn't give you the safety margin that keeping a good turns count
rule does. All one needs to do is stop adding turns, add some tape
turns, and then start another set of turns. Thus guaranteeing that
you'll never have any two turns near each other that are to far apart
in voltage. That is layered construction. Segmented bobbins usually
don't give much room to go overboard on turns unless you are using
some insanely fine gauge wire.

C
Replies
2
Views
832
Claude
C
N
Replies
16
Views
1K
Eric R Snow
E
B
Replies
1
Views
849
Terry
T
Replies
3
Views
382
Replies
2
Views
549