DIY winding your own inductors - worth it ?

[MarcG]

OK, cost of the 14 g. perfect lay inductors have really um... gone up. So is there much quality lost in winding your own by hand on say on PVC pipe former and gathering it up with wire ties ? I was thinking of using some 14 g. plain enamel wire and following the lalena calculator and using an inductance meter to get it spot on. Is this a great way to save money or a waste of time. I'm building four Modulas and these add up..

Marc

[Bri]

I also considered this approach but when I priced the appropriate lengths of 14ga magnet wire it didn't amount to much savings. Maybe I didn't spend enough time finding good wire prices?

[jquin]

Well I cant speak for the cost as the price of copper has gone up a lot and I have access to free wire.

I have wondered about winding a doughnut shaped inductor around wax and then melting the wax away.
I doubt the advantage would be effort unless you are doing it for fun like would.

Regards
John Quin

[MarcG]

Then what are acceptable sources for wire ? Is there a spec. for the type of wire ? Triple virgin, cryogenically treated grain oriented OFC ? 8O
Well, seriously is there a spec for the copper content and insulation ? Do I go to a local supplier and say " Hey how about 100ft of that plain 14g groundwire you have there..... :B

[Volenti]

If you intend to do a fair amount of diy inductors (or you simply want to be spot on) I suggest investing in an LCR meter, that way you can measure the inductor even as your winding it to get the exact inductance required.(or modify the value of an existing inductor)

I come from a background of designing custom passive x-overs for both car and home audio and we simply use standard enamel coated winding wire of whatever size is necessary to achieve the desired DCR.

You basically want a neat compact coil with the least amount of "air" between both the turns and layers as possible.

[ThomasW]

One can buy wire in bulk from electric motor rebuilders (it's actually cheaper from the companies that supply the rebuilders). It's sold in 5 gal buckets and usually weighs ~70lb/bucket

That's what I use with my powered winder....

https://web.archive.org/web/20151002174103/http://home.comcast.net/~audio-worx/page95Coilwinder.html

[MarcG]

Would this LC meter have the right range or be appropriate for winding x-over coils ?

http://www.circuitspecialists.com/prod.itml/icOid/3394

Thanks, marc

[digital desire]

That is very impressive!
What would (just an arbritary example) a $20 sidewinder cost to make with copper at your price from the bucket? IOW, how much does the same langth of copper wire cost?

[JonMarsh]

Would this LC meter have the right range or be appropriate for winding x-over coils ?

http://www.circuitspecialists.com/prod.itml/icOid/3394

Thanks, marc

Yeah, that would work OK- you'd be using on the lowest scale most of the time.

[digital desire]

±2% of full scale ±1 digit
So that means if you were shooting for a 1.2 coil, you could wind up with a 1.3? (The last digit?) Would that be significant in most crossover apps?

[MarcG]

My local rewinder says copper wire prices have gone up 7 times in the last 12 months. Scrap too.
Currently his wire price is $7.80 / pound.

Yea I too am interested in the wire cost of the completed product.

I wonder approx how many 1.2 mH coils you could wind off 10lbs of 14g?


I see myself listening to hypnotic music as I sit cross-legged on the floor hand winding coils. Can't be that much harder than unwrapping / coiling up the Christmas lights....

PS. the audio coils I have been looking at are +/- 5%

[---k---]

One can buy wire in bulk from electric motor rebuilders (it's actually cheaper from the companies that supply the rebuilders). It's sold in 5 gal buckets and usually weighs ~70lb/bucket

That's what I use with my powered winder....

https://web.archive.org/web/20151002174103/http://home.comcast.net/~audio-worx/page95Coilwinder.html

ThomasW,

I've been to your website many times. But you often shock me with the pages you post here. Am I just not looking hard enough, or are you hiding a bunch of pages? If it is the later, shame on you! :fingerwaving:

[ThomasW]

Would this LC meter have the right range or be appropriate for winding x-over coils ?

It's fine.

The problem with handwinding is keeping the layers tight and even. If you can fabricate something with a crank to spin the core (even by hand) it's much easier on the hands and makes better cores.

That is very impressive!
What would (just an arbritary example) a $20 sidewinder cost to make with copper at your price from the bucket? IOW, how much does the same langth of copper wire cost?

The cost is by the pound.

[Paul H]

±2% of full scale ±1 digit
So that means if you were shooting for a 1.2 coil, you could wind up with a 1.3? (The last digit?) Would that be significant in most crossover apps?

That means + or - 1 digit on the resolution for that setting in the meter - if you were measuring a 1.2 mH coil you'd set that meter on the 2mH range, with a resolution of 1uH, or 0.001 mH.

Your measurement would be accurate to +-2% +- 0.001 for those specs.

[ThomasW]

Thomas,
I've been to your website many times. BUt you often shock me with the pages you post here. Am I just not looking hard enough, or are you hiding a bunch of pages? If it is the later, shame on you!

Over the years I've uploaded pics and created pages to answer questions. Those misc pages aren't indexed or cataloged. I had to dig deep into the "My Webs" doc folder to find that link, since I couldn't remember where it was..... ops:

[JonP]

My local rewinder says copper wire prices have gone up 7 times in the last 12 months. Scrap too.
Currently his wire price is $7.80 / pound.

Yea I too am interested in the wire cost of the completed product.

I wonder approx how many 1.2 mH coils you could wind off 10lbs of 14g?


I see myself listening to hypnotic music as I sit cross-legged on the floor hand winding coils. Can't be that much harder than unwrapping / coiling up the Christmas lights....

PS. the audio coils I have been looking at are +/- 5%

Well, I heard a news bit a week or so ago which stated some of these commodities that have been shooting up are coming back down.. Copper was mentioned as having dropped 35% from the peak just recently. Here's hoping we see resulting price drops soon!

I just was playing around with the 2.75mH's I got from Mad (Solen 14g) and weighed them. At about 1.9lbs, the $14.80 raw copper price is just under half of the $30.50 asking price! (not to mention the Erse 14g 2.5mH, which is a bit more for a bit less) So, that would be quite some savings at that size of coil.

As an aside, I bought the larger values of .47mH and 2.75mH for a Modula MT pair, and unwound them to .40 and 2.6mH, took measurments with a $$ pro LCR meter, reported number of turns to remove, etc... if anyone is interested, it's posted on the Modula MT "Missions Accomplished" thread.

[marc g]

So, Thomas, do you have a hidden archived pic of a less ambitious winder ? Maybe an attachment for a vari-speed drill ? ops:

[ThomasW]

So, Thomas, do you have a hidden archived pic of a less ambitious winder ? Maybe an attachment for a vari-speed drill ? ops:

Nope it would be trickey because one needs a way to control the speed when using a powered winder. That's what that big black pedal thing is setting on the floor beside my powered unit.

Something cobbled up from the likes of an apple peeler would do for a hand cranked device...

[JonP]

Now, if you could get a hold of a junk sewing machine... hmmm... maybe not enough torque for the heavy gauge stuff.

Actually, checking surplus places for motors with speed controls, maybe even with a gear reduction, or pullys and belts.. would be an idea. A pretty small motor geared down would be sufficent.

What kind of max speed would you say is enough, Thomas? Probably about 100rpm?

[marc g]

OK, I found a couple of coil winding machines.
Could anyone with "hands on' experience steer me to a choice. They all seem pretty reasonable at under $100. Way more reasonable than spending a day or two...or...more. :roll: making your own out of bits of sewing machines and such.


A Morris http://cgi.ebay.com/Morris-Coil-Wind...QQcmdZViewItem


a Tesla http://cgi.ebay.com/NEW-tesla-coil-m...QQcmdZViewItem

generic http://cgi.ebay.com/Coil-audio-Outpu...QQcmdZViewItem

Tatoo coil winder ?

http://cgi.ebay.com/Tattoo-Machine-Hand-Cranked-Coil-Winder-PRO-style-N-R_W0QQitemZ150083029647QQihZ005QQcategoryZ16705QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Anyone have experience with any of the above winders ?
The Morris seems to have a winding "scatter guide" does this work for tidy 14g coils or is it too light duty for that ? The tatoo winder 8O hmmm seems bulletproof but no winding counter.

[ThomasW]

Now, if you could get a hold of a junk sewing machine... hmmm... maybe not enough torque for the heavy gauge stuff.

Actually, checking surplus places for motors with speed controls, maybe even with a gear reduction, or pullys and belts.. would be an idea. A pretty small motor geared down would be sufficent.

What kind of max speed would you say is enough, Thomas? Probably about 100rpm?

For a max speed that's fine, but one must have a rheostat to lower the speed to a crawl.

Power winders like the one I have (we didn't build it, Jon inherited it when his speaker building mentor died) are tickey to use, and very hard on the hands/fingers.

[ThomasW]

OK, I found a couple of coil winding machines.
Could anyone with "hands on' experience steer me to a choice. They all seem pretty reasonable at under $100. Way more reasonable than spending a day or two...or...more. :roll: making your own out of bits of sewing machines and such.

Having a counter is really important for people like me with a short attention span...... :B

[JonP]

For a max speed that's fine, but one must have a rheostat to lower the speed to a crawl.

Power winders like the one I have (we didn't build it, Jon inherited it when his speaker building mentor died) are tickey to use, and very hard on the hands/fingers.

Oh yes... I was assuming on any motor/reduction thing found you want one with some kind of speed control. And with a very flexable and easily used one, i.e. a foot pedal control.

I'd think you want both hands free to control the wire, and the ability to instantly stop or slow down in case of problems.... well, pretty much defines foot pedal control.

I also can imagine wrangling 14 or 12g wire, and getting your finger in there, could be very bad...

[ThomasW]

With mine the hand feeding the wire is covered with a leather glove, it provides the tension for the wire. That hand is 8" or so away from the bobbin so there's no risk of getting fingers in the way.

The foot control allows a soft start and the ability to speed up. Problems occur when one gets to the edges of the bobbin, and needs to reverse direction for the next layer. Frequently the wire bunches up and has to be backed off a few turns and restarted.

Mine actually has a reverse count shut-off. One dials in the number of turns desired. As the coil is spinning the device counts down, shutting off when it's made the specific number of turns.

Mine winder is 30yrs old, and was custom build by the engineer for a speaker company called Ultraphase. If it would be helpful I can take close up pictures of the mechanism.

[marc g]

Thomas when you say "reverse direction" does that apply to guiding the wire back to the starting side of the bobbin ?
A picture of the counter mech would be helpful too.

Marc

[ThomasW]

Thomas when you say "reverse direction" does that apply to guiding the wire back to the starting side of the bobbin ? Marc

Yes I'm referring to when the wire has reached one edge of the bobbin, and needs to change direction to wind the next layer. This is the most problematic situation for a powered winder, because the wire often tries to climb up the side of the bobbin instead of reversing direction.

[Eric S]

OK, this discussion has caught my attention since I have just added up the cost of 14g inductors for the AVRO project. It looks like building 5 AVROs will need in the neighborhood of $1300 worth of inductors 8O :E (the caps aren't exactly cheap, either...)!

Thomas, I was wondering if you could provide some ballpark estimates for me on the cost of the bobbins and the bulk wire you have found. A winder can be had on e-bay for $100. Is $7.50 per pound of enamel coated 14g wire resonable (thats $175 just in copper alone) ? What is a reasonable price to pay for an empty bobbin (looks like I will need 40 of them)?

And finally :B , how do you measure the inductance while you are winding the inductor? Would you need to scrape the enamel from the wire to get a reading? Do you then need to re-cover the scraped spot as you continue to wind?

Using the figure of $7.50 per pound of 14g solid core enamel coated wire, it looks like an estimate of $650 worth of wire (just over 85 lbs for coils for 5 AVROs). Throw in $100 for the winder, now we are up to $750. I would assume 40 empty bobbins could be had for another $100, making a total of $850 to roll your own vs. nearly $1300 to purchase them already made.

I'm starting to think that winding my own, even for this one project will be a large expense saver :T

Marc: PartsExpress indicates that a 1.2mH 14g air core inductor weighs just under 1.5 lbs. Looks like 10 lbs of wire would net you 6 inductors...

Thanks,
Eric

Edit to add: 14g solid core copper weighs 12.43lbs/1000ft. A 70lb bucket of wire should thus contain somewhere near 1 mile of wire (5631 ft, not counting the weight of the enamel or the bucket)

[soho54]

You might as well bump the wire up to 12g, to copy the North Creek coils Jon used. :B

Anyone near the GA/FL line wanna go halves on some 12g coils?

[Eric S]

Funny that you chime in here, Jacob. I was thinking of you while I was writing my message. I'm slowly building my pile of materials. I have the TC sounds woofs, the Dayton tweeters, and am now trying to figure out what I can hock to buy a 10-pack of the M8a's :W

Eric

[ThomasW]

It's easier to both find and wind 15 gauge wire. Bobbins are usually $.20 ea in quantity.

[soho54]

This site Alpha-Core seems to have some good prices on their round mag wire.

14g w/150deg insulation is $5.67 per pound (10lbs minimum to meet $50 minimum order) plus shipping (UPS Ground $10.85 to my door in Ga).

There is a discount for orders over 50lbs.

[Outfitter]

Thanks for the heads-up Soho!

[soho54]

I stumbled across this site Shavano Music. It has an online air core inductor calculator for layman. I haven't checked the math yet, but it looks nice and should get you in the ballpark.

It's fun to play with anyway. :T

There is also a few more places to order wire from listed there.

[Eric S]

The Alpha-Core web site has some very nice prices! Thanks, Jacob!

Eric

[Outfitter]

So here is another place-shipping is just a little cheaper to my location.
It states that it's a "heavy build" compared to single/double builds.

http://www.magnet4less.com/AWG14.html

So the question remains, what is the best choice for price/value? Over at Alpha-core there is a choice of standard 150C, or 180,200, 220, 240C. Is that in reference to the builds?

[soho54]

"heavy build" is in reference to the insulation.
The Magnet 4 Less site states a 200deg rating in the link.

In electric motors a high rating is sometimes required, because of the heat generated in those applications. If you are killing air cores with heat you are using way to light a gauge wire, or are deaf from the stadium PA system you have in your apartment. :B

I like the lighter insulations myself, but if the 200deg stuff is cheaper for you go for it.

Maybe one of the more experienced ones will chime in on their preferences.

[cotdt]

i think it's much easier to make your own inductors out of foil. i've made some copper foil inductors by hand and it was very easy to do, and you don't have to worry about alignment problems or anything like that. standard air core inductors require tools to make good-looking ones, and a bobbin.

[Eric S]

It's easier to both find and wind 15 gauge wire.

Thomas, I take it from your comment that there are no problems using 15ga inductors for the AVROs... Do any of the resistor values in the crossovers need to change?

Thanks,
Eric

[JonP]

So the question remains, what is the best choice for price/value? Over at Alpha-core there is a choice of standard 150C, or 180,200, 220, 240C. Is that in reference to the builds?

Yep.. have a bit of magnet wire experience, and it's not an issue for this application. They never get very hot, unlike in a motor, so whichever is cheapest. The "build" of the insulation also is important more for rugged duty, higher voltages, etc... like in motor duty.

Only downside I can think of to heavy build insulation would be that it's a bit harder to scrape off for soldering... big deal...

[JonP]

i think it's much easier to make your own inductors out of foil. i've made some copper foil inductors by hand and it was very easy to do, and you don't have to worry about alignment problems or anything like that. standard air core inductors require tools to make good-looking ones, and a bobbin.

Curious, where do you find foil with insulation, or do you roll them with some insulating film between?

Where are you finding suitable foil? How's the cost comparison with plain wire for the same gauge equivalent?

[Outfitter]

This may work for foil inductors...

http://www.alphacoredirect.com/index.html?lang=en-us&target=d50.html

[cotdt]

This may work for foil inductors...

http://www.alphacoredirect.com/index...arget=d50.html

those would work beautifully. but what i had on hand had no insulation, so i just used plastic film. i think plain old tape would work too, though.

[Outfitter]

So, I think it's safe to say that buying magnet wire from Alpha-core would result in substantial savings. I priced a dozen or so inductors ranging in gauge and mH, and and it's 1/3 of the cost from PE or Madisound.

Now next step is to price a winder-I like a couple that were posted above, and try to find bobbins. I think that it would be easier to wind if there was a starting and stopping point on the bobbin. Any thoughts on where to find them?

[cotdt]

So, I think it's safe to say that buying magnet wire from Alpha-core would result in substantial savings. I priced a dozen or so inductors ranging in gauge and mH, and and it's 1/3 of the cost from PE or Madisound.

Now next step is to price a winder-I like a couple that were posted above, and try to find bobbins. I think that it would be easier to wind if there was a starting and stopping point on the bobbin. Any thoughts on where to find them?

you can wrap them around a piece of wood

[marc g]

I found a site that had students wrap them on bobbins made of pvc. You could wrap them between two plywood washers and disassemble the washer afterwards - slide the coil off and tie it up with wire ties. I don't know if potting them would help but it works for winding guitar pickups. Being potted is a good reason to have a counter on your winder. 8O