I want to hand make a 0.22mh coil. I use Shavano"s reference, 60 turns (39 ft.) of 14 AWG wire on a 1.34 inch bobbin. I shall borrow someone's reactance meter to get the desired MH. The question is:
I cannot make parallel layers as some turns are overlapping each other randomly. Does that matter ?Or are there any simple methods to wind the core?
I cannot make parallel layers as some turns are overlapping each other randomly. Does that matter ?Or are there any simple methods to wind the core?
hi yukyukyuki, Neville Thiele (of Thiele-Small fame) wrote an article for "The Journal Of the Audio Engineering Society" on aircored inductors some years ago and I recall he made the point that radom winding of the wire seemed to be quite stisfactory. If he found it okay then I suspect the rest of us can. By the way if you are winding many aircored coils you might try tracking this article down as it was very practical and revolved around a novel way of looking at the problem. If I find my copy I'll post the reference.
I've wound quite a few of my own coils. I used a short section of 22mm copper tube, with two rings of MDF squeezed onto it the right distance apart. The rings keep things tight and allow perfectly parallel layering. It probably doesn't make them perform any better, but it makes the coils look much neater:
Here's another very useful coil designer. You can change all of the dimensions of the coil to suit. It also tells you the weight and length of wire required and works in AWG, SWG or metric.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Here's another very useful coil designer. You can change all of the dimensions of the coil to suit. It also tells you the weight and length of wire required and works in AWG, SWG or metric.
Inexpensive, acurate, sound-card impedance meter:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=64357&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=64357&highlight=
Jonathan Bright said:
The Thiele method is what is in the Loudspeaker Design cookbook and also what the Shavano calculator uses. It is also the logic behind the graphs in the Weems books. FWIW, Weems said that scramble wound coils work OK as long as the windings are not too messy.
I think that winding coils is not worth the effort, it might have been a few years ago when large gauge coils were hard to find, but they are easy to find and not much more expensive than the copper nowadays....
Back in the days when a 5mH coil cost 5 bucks, I decided I was going to wind my own and save some money. As it turns out it cost me 6 bucks of magnet wire and about a half hour to wind the same coil. And mine never did look that purdy.
I have not compared prices recently. Actually, not in the last thirty years. I just buy them.
I have not compared prices recently. Actually, not in the last thirty years. I just buy them.
There is a real lack of decent inductor supplies in the UK. A friend of mine got some 16 Gauge stuff for winding some inductors and I have some 12Gauge. I'll try ang get some details but its still not cheap, £10 per kilo with 10kg min order rings a bell, + Vat + P&P of course.
Do you know anyone with a small lathe, that speeds things up a lot!
Do you know anyone with a small lathe, that speeds things up a lot!
Puggie, for my latest loudspeaker project I needed a 2.2mH inductor with low Rdc. I opted for air core as it's directly in the signal path of the midwoofer. The only place in the UK that does air-cored inductors seems to be Wilmslow Audio, and the Rdc of theirs was too high. In the end I bought Intertechnik inductors from Strassacker in Germany. The delivery charge was quite reasonable and an order placed on Sunday evening arrived on the Thursday morning. They sell the full range of Intertechnik inductors including Tritecs, as well as the Mundorf copper foil and (fiscally insane) silver and silver/gold foil inductors.
Hi Waltona,
I have bought from the Scientific Wire Company. http://scientificwire.com/index2.html
I have bought from the Scientific Wire Company. http://scientificwire.com/index2.html
gfinlayson said:
Wilmslow aren't the only folks in the UK to do aircore inductors.
http://www.falcon-acoustics.co.uk/pl28p6.htm
Falcon will custom wind any value for you should you require but the link above is the price of the most common ones.
I just went through a building the calc in excel and setting up a winder, in my mind. Then I priced the magnet wire 
My calcs put me at about a 10% savings if I buy the wire in large quantities, not enough to make it worth while. Even priced some spool winding machines $10K for a new, about $2k for used. If you can find a good source for the wire, you might be able to save a little, but it would be hard to compete with the vendors.
I think I'll still build the winding machine just to do it and be able to make a coil when ever I want to. you never know, some one might want to buy it.
My calcs put me at about a 10% savings if I buy the wire in large quantities, not enough to make it worth while. Even priced some spool winding machines $10K for a new, about $2k for used. If you can find a good source for the wire, you might be able to save a little, but it would be hard to compete with the vendors.I think I'll still build the winding machine just to do it and be able to make a coil when ever I want to. you never know, some one might want to buy it.
I've just had a look at the falcon inductor prices.
I bought my last lot of inductors from Strassacker in Germany and their prices are much, much cheaper. eg. 2mH (1mm) from a UK supplier is about £10, from Germany it cost about £3.50! Ok there is p&p to consider but you only need to buy a few inductors to cover the difference. Their service was excellent.
In the past I have had some inductors from Wilmslow and IMO the quality was very poor. Thin wire (high DCR) and high price.
I have noticed that on ebay at the moment there is somebody selling Intertechnik inductors at amazing prices. He has limited values but it is well worth a look. Search for intertechnik and look in ebay shops.
Al
I bought my last lot of inductors from Strassacker in Germany and their prices are much, much cheaper. eg. 2mH (1mm) from a UK supplier is about £10, from Germany it cost about £3.50! Ok there is p&p to consider but you only need to buy a few inductors to cover the difference. Their service was excellent.
In the past I have had some inductors from Wilmslow and IMO the quality was very poor. Thin wire (high DCR) and high price.
I have noticed that on ebay at the moment there is somebody selling Intertechnik inductors at amazing prices. He has limited values but it is well worth a look. Search for intertechnik and look in ebay shops.
Al
I would agree that it is a bit of a nightmare getting decent inductors in the uk- and decent resisitors too!
If you have to wind your own, try http://www.wires.co.uk/acatalog/sx_ec_wire.html they have lots of different diameters
You can also get air cored inductors from Audiocom- http://www.audiocom-uk.com/ but they are a bit expensive and the last time i tried ordereing from them the website broke, so best avoid.
As others have said, Stessacker- http://www.lautsprechershop.de/hifi/index_en.htm - offer excellent service (I had an email conversation with the guy there asking for some information at 11:30pm one night with immediate responses!) and the bits I bought on the sunday night arrived on the wednesday morning. Only accept paypal for payment, but they have all the bits you need
If you have to wind your own, try http://www.wires.co.uk/acatalog/sx_ec_wire.html they have lots of different diameters
You can also get air cored inductors from Audiocom- http://www.audiocom-uk.com/ but they are a bit expensive and the last time i tried ordereing from them the website broke, so best avoid.
As others have said, Stessacker- http://www.lautsprechershop.de/hifi/index_en.htm - offer excellent service (I had an email conversation with the guy there asking for some information at 11:30pm one night with immediate responses!) and the bits I bought on the sunday night arrived on the wednesday morning. Only accept paypal for payment, but they have all the bits you need
Winding a coil is so easy, just use a drill with adjustable speed. Better with two people, one guide the wire and the other control the drill...
We did that at elementary school grade 3. Each coil was perfect or almost perfect, just like a sewing machine can wind perfect or almost perfect "coils" of "wire"... same principle. It was also damn fast. Several layers of wire with about 20 turns per layer took a few minutes at most.
We did that at elementary school grade 3. Each coil was perfect or almost perfect, just like a sewing machine can wind perfect or almost perfect "coils" of "wire"... same principle. It was also damn fast. Several layers of wire with about 20 turns per layer took a few minutes at most.
It might make sense to wind your own for really big inductors and large wire gauges. Looking for a 2.4mH 12ga coil, I found a spool of 12 ga magnet wire on eBay big enough to wind three for a little more North Creeks' price for one.
Smaller inductors and retail price for wire don't make sense to me either.
Smaller inductors and retail price for wire don't make sense to me either.
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