I know some guys here build transformers. Is there any one who has made a inductor ?
I need 1 aircore 2.0 mH with 14-15 guage wire ?
If someone can tell me how and what - that would be awesome.
Thanks.
Srinath.
I need 1 aircore 2.0 mH with 14-15 guage wire ?
If someone can tell me how and what - that would be awesome.
Thanks.
Srinath.
I like this calculator. Inductor Designer / Calculator and it looks like you will need about 1.25 lb of # 14 wire.
If you went to using # 16 wire you could get by with just .75 lbs of wire with a dcr of about .4 ohms where using # 14 wire only brings you down to a dcr of .26 ohms.
Let me try those - thanks guys.
The $28 for the inductor seemed excessive to me.
But wire is about the same $$$.
I may by a 5 lb hunk and wind away and keep the rest for later.
Now a steel core is OK too - the original one is a ferrite core - can I use a steel rod with masking tape over it ?
Thanks.
Srinath.
The $28 for the inductor seemed excessive to me.
But wire is about the same $$$.
I may by a 5 lb hunk and wind away and keep the rest for later.
Now a steel core is OK too - the original one is a ferrite core - can I use a steel rod with masking tape over it ?
Thanks.
Srinath.
Hi,
A steel rod with no laminations will be very poor.
A Ferrite rod is far better, why they are used.
A steel laminate is a square section core, usually,
unless its made of steel wire, like a C core.
No masking tape is needed for insulated windings.
rgds, sreten.
A steel rod with no laminations will be very poor.
A Ferrite rod is far better, why they are used.
A steel laminate is a square section core, usually,
unless its made of steel wire, like a C core.
No masking tape is needed for insulated windings.
rgds, sreten.
Srinath, if you have decised you can go with an iron core coil I probably
have one in my stash you can have just for postage.
have one in my stash you can have just for postage.
I cant raid your stash ... its there to bail you out one day. Info and knowledge is plenty. I have a stash going here too, and I am tempted to offer it ... if I can find it or remember what I have in the stash.
I'm trying to save $3 - forget it, parts express, $28 a piece for air core, and I need 2 cos the other one is ferrite ... or I'll buy 2 1.8 ferrites for that price ... and swap both ...
OK I have a question ...
This is in the bass section of a B&W 802 matrix. It was broken off in shipping.
I found a 2.0 mh in the mid bypass section in a Infinity 7 Kappa XO . Very very thin wire ... I will end up burning it when I power it up wont I ???
I'll buy a bunch of parts form Parts express. I need 2 caps anyway. Need more parts too I'm sure.
Thanks guys, you are great.
Cool.
Srinath.
I'm trying to save $3 - forget it, parts express, $28 a piece for air core, and I need 2 cos the other one is ferrite ... or I'll buy 2 1.8 ferrites for that price ... and swap both ...
OK I have a question ...
This is in the bass section of a B&W 802 matrix. It was broken off in shipping.
I found a 2.0 mh in the mid bypass section in a Infinity 7 Kappa XO . Very very thin wire ... I will end up burning it when I power it up wont I ???
I'll buy a bunch of parts form Parts express. I need 2 caps anyway. Need more parts too I'm sure.
Thanks guys, you are great.
Cool.
Srinath.
Iron is a superhighway for flux.
If half the round trip distance is cheated by iron,
then your inductance might have just doubled.
But there are consequences.
Empty space has no upper limit of flux, and its
properties never become non-linear. Put iron or
similar in the path, and you now have an upper
limit for how many carloads of flux can ride on
that superhighway.
Above that limit, the iron ceases to help. And you
have a useless ghost of a highway where there was
once an iron bar. Your flux sees only space, and the
inductance suddenly drops back to the original air
coil value.
This wrenching change is a non-linearity. And worse,
its going to waste some of your stored energy and
not give it back (like an imperfect spring that doesn't
fully return to original shape).
And then you got eddy currents. Unless the iron is
divided into powder and insulated, or rolled to thin
strips and insulated, or baked into a ceramic. It will
conduct current just like the secondary winding of a
transformer. Only this is not useful, just wasted heat.
If you put iron in there. It needs to be laminated
to cut down the eddies at the very least. And you
must leave a substantial air gap, to keep too many
carloads of flux from overcrowding the highway.
If you completely close the loop with iron and forget
to leave a gap, then flux will flow too easily. You will
have lots of Henries, but will saturate before you can
do anything fun with it. Oddly enough, only the empty
space stores energy. Too much iron worse than none
at all.
And it needs to be low "remnance". Like will stick
to a magnet, but it won't remember any magnetism
(and permanently attract other things) after you
remove the source. Varies with alloy and heat treatment.
Any after any machining you may need to re-anneal.
Else you waste energy in that imperfect spring.
Don't be tempted by bailing wire. It will block eddies
just like laminations would. But its usually not a good
alloy for low remnance. And the stress of being drawn
into wire makes the flux prefer to go through sideways,
not lengthwise as you might expect....
If half the round trip distance is cheated by iron,
then your inductance might have just doubled.
But there are consequences.
Empty space has no upper limit of flux, and its
properties never become non-linear. Put iron or
similar in the path, and you now have an upper
limit for how many carloads of flux can ride on
that superhighway.
Above that limit, the iron ceases to help. And you
have a useless ghost of a highway where there was
once an iron bar. Your flux sees only space, and the
inductance suddenly drops back to the original air
coil value.
This wrenching change is a non-linearity. And worse,
its going to waste some of your stored energy and
not give it back (like an imperfect spring that doesn't
fully return to original shape).
And then you got eddy currents. Unless the iron is
divided into powder and insulated, or rolled to thin
strips and insulated, or baked into a ceramic. It will
conduct current just like the secondary winding of a
transformer. Only this is not useful, just wasted heat.
If you put iron in there. It needs to be laminated
to cut down the eddies at the very least. And you
must leave a substantial air gap, to keep too many
carloads of flux from overcrowding the highway.
If you completely close the loop with iron and forget
to leave a gap, then flux will flow too easily. You will
have lots of Henries, but will saturate before you can
do anything fun with it. Oddly enough, only the empty
space stores energy. Too much iron worse than none
at all.
And it needs to be low "remnance". Like will stick
to a magnet, but it won't remember any magnetism
(and permanently attract other things) after you
remove the source. Varies with alloy and heat treatment.
Any after any machining you may need to re-anneal.
Else you waste energy in that imperfect spring.
Don't be tempted by bailing wire. It will block eddies
just like laminations would. But its usually not a good
alloy for low remnance. And the stress of being drawn
into wire makes the flux prefer to go through sideways,
not lengthwise as you might expect....
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Aaaah ... that's good knowledge ... I'll re-read it ... I dont think I understand 1/2.
Cool.
Srinath.
Cool.
Srinath.
16 AWG Copper Magnet Wire MW0012 - 1.5 lb 188 ft 155C Magnetic Coil - Red
I like these guys, they are out of California and have fantastic prices on 440V Motor Run Capacitors also.
Their price for 1.5lb of 16awg magnet wire is only $23, you could wind both of your inductors from 1 spool of that size.
I like these guys, they are out of California and have fantastic prices on 440V Motor Run Capacitors also.
Their price for 1.5lb of 16awg magnet wire is only $23, you could wind both of your inductors from 1 spool of that size.
I have bought wire from temco before.
Just that if I am buying for this, I will buy a big bunch and wind a few probably.
Thanks,
Srinath.
Just that if I am buying for this, I will buy a big bunch and wind a few probably.
Thanks,
Srinath.
Well, the trick is to balance iron loss vs copper loss.
Ideally should be about 50/50. With just the right
amount of gap to store as much energy as the iron
can reasonably handle.
Empty space has no iron loss or non-linearity. But
without iron cheats, you might need too much wire.
Too much wire is big, expensive, and causes just
as many problems. Eddie currents swirl sideways
in thick wire just as easily as they do in thick iron.
If you make a nearly complete loop of iron with
one very small gap where all the energy storage
is concentrated. Keep thick wires well away from
that gap, else the concentrated field there will
stir sideways swirling currents in the wire and
burn them. Not a problem for a simple laminated
bar with a huge gap from end to end.
Some folks rope together a bunch of small wires,
to block eddies and for other reasons. Even if you
may see that in high frequency power supplies,
you need only one solid wire for audio frequency.
Obviously there is a bunch of math to all this.
I prefer understanding first, math later...
Inductance works precisely because of nothing.
You could say the same for capacitance.
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So - you're saying - I could calculate the windings for air -
And use a steel bar in the same Dia as the calculated air dia, and wind 1/2 the turns ???
Say 1" air gap and 100 turns = 2 mH, I can do 1" steel rod and 50 turns for 2 mH ???
Thanks,
Srinath.
Provided you don't go silly and over-saturate the iron:
Inductance rises with the number of turns SQUARED.
Quadruple the turns, inductance goes up by 16.
Double the turns, inductance goes up by 4.
Halve the turns, inductance goes down to 1/4.
-on the other hand-
Inductance goes down in proportion to the effective
gap length of the magnetic path. No square rule.
Saturation also goes down (away from the iron limit)
in proportion to the same gap length. No square.
Saturation goes up with the number of Ampere turns.
No square.
Inductance rises with the number of turns SQUARED.
Quadruple the turns, inductance goes up by 16.
Double the turns, inductance goes up by 4.
Halve the turns, inductance goes down to 1/4.
-on the other hand-
Inductance goes down in proportion to the effective
gap length of the magnetic path. No square rule.
Saturation also goes down (away from the iron limit)
in proportion to the same gap length. No square.
Saturation goes up with the number of Ampere turns.
No square.
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So, lets say I have an inductor thats got a
problem I can hear because its saturating.
How do I fix that???
One possible answer is to wind on twice as
much wire, and quadruple the length of the
gap to bring the inductance back down.
My wire change made saturation twice as bad,
but my gap change reduced saturation 4 times.
Together, inductance did not change, but I'm
now only half as saturated.
See how that's just the opposite of intuition.
Its saturating, so wind on more wire. WHAT?
Of course you gotta widen the gap or its worse.
But that's how all that annoying math works...
You can only store energy in space, not iron.
If iron can't handle the flux, use more space.
Requires more wire, but not linearly more.
Thankfully because of that square rule...
problem I can hear because its saturating.
How do I fix that???
One possible answer is to wind on twice as
much wire, and quadruple the length of the
gap to bring the inductance back down.
My wire change made saturation twice as bad,
but my gap change reduced saturation 4 times.
Together, inductance did not change, but I'm
now only half as saturated.
See how that's just the opposite of intuition.
Its saturating, so wind on more wire. WHAT?
Of course you gotta widen the gap or its worse.
But that's how all that annoying math works...
You can only store energy in space, not iron.
If iron can't handle the flux, use more space.
Requires more wire, but not linearly more.
Thankfully because of that square rule...
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A laminated iron bar is also not exactly half
the path through space. That was a very crude
approximation for purpose of keepin' it simple.
Maybe its only a third, or don't get me lying
about an exact number here...
The return path through space will loop back
around the bar in every possible direction
to minimize the reluctance (like resistance
only magnetic). Look at some pictures of
iron filings and a bar magnet...
Not a simple shape like a low reluctance bar,
where flux prefers to stay on the easy path.
the path through space. That was a very crude
approximation for purpose of keepin' it simple.
Maybe its only a third, or don't get me lying
about an exact number here...
The return path through space will loop back
around the bar in every possible direction
to minimize the reluctance (like resistance
only magnetic). Look at some pictures of
iron filings and a bar magnet...
Not a simple shape like a low reluctance bar,
where flux prefers to stay on the easy path.
Attachments
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I've not done anything as big as a 2.0mH air core but the principals would be the same. http://www.diyaudio.com/forums/blog...g-your-own-adventure-coil-winding-part-i.html
http://www.diyaudio.com/forums/blog...-your-own-adventure-coil-winding-part-ii.html
Air core is probably impractical though for something that size in that gauge of wire!
Tony.
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