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Discussion Starter #21
I didn't think you were having ago. I just want to be as thorough as I can. Especially when things can get very complicated very quickly in this field.


Although it is hard, you can get away without having an inductance meter. but it requires a bit of patience and a lot of testing/retesting until you are happy with the results.
 

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Discussion Starter #22
Well I finally got hold of an off-the-shelf inductor, I grabbed a couple of .22mH but I needed .6mH so it isn't exactely a fair comparison but good enough for what I have done. Both off-the-shelf inductors measured to there rated henries, however the dcr was rated at .3ohms (a little too hopefull I think), they actually measured at .8 ohms. I require a 0.6mH for some speakers I am currently working on, so I decided I would spend a litle more time on these inductors (6 minutes instead of five) and see if the results are better or worse. This is the inductor all wound up on the meter:

measure.jpg

As you can see 0.59mH. Not bad considering the nearest off-the-shelf is either 0.56 or 0.82.
The dcr was 1.7ohms, which is also within cooee of the expected. The other advantages I had with this was that not only is it closer to what I actually need but it was half the price and can handle more power. The ots inductor was only rated to 100watts yet the DIY should be able to run at 180watts.

One last shot:

coil 018.jpg
 

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well, the inductor is probably the ONLY one you can build yourself :D
You might be able to wrap your own non-inductive resistors as well. There is at least one outfit that sells these for 50$ a piece! I cannot imagine they are worth it but...
 

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The inductors you are making are every bit as good as the ones you can buy commercially provided you can get good wire. Hint- Know any places that sell supplies to re-wind electric motors? You can get magnet wore from them cheaper and yes, it is the same stuff, but the annealing is more likely to have been done correctly and the lacquer is likely going to be a bit better quality- flexible and heat resistant. You will also have a much wider selection of wire diameters and you may even find some tweak stuff for use in high end applications.

One caution with your winding gizmo thing-a-ma-bob. Careful to not cut or scratch the wire when you are removing the finished product from the mandrel. You might consider wrapping the mandrel with a piece of paper and wind the coil onto the top of that- then they slide right off the mandrel with no risk of nicks. The nicks are more critical if you are doing iron cores and not winding direct to the core.

If you have a good LCR and you are not in a hurry, you can wind 1% without too much issue.
 
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