Winding your own inductor

[shawsofhell]

I want to wind my own inductor for a wah pedal. I have been able to find a machine that will count the number of turns I'm doing which should be handy!

Ok my questions:
1. What is the best type of core to use (material, diameter, height)?
2. What gauge wire should I use?
3. Does anyone have any resources I should read or tips?

PS. Please don't tell me that I should just buy a new one!

[thomas2]

you should just buy a new one  :twisted:

[thomas2]

no.. seriously.. this is interesting.. i've thought about it also.
let's hope someone has the answers

[Athin]

wind it on whatever you want, though the plastic carcas (I think that's the name for it) from a trannie would be purrfect. You could try and calculate the inductance (L = (Mu_r * Mu_0 * n^2 * A)/l), but I'd make the inductance meter from here http://braincambre500.freeservers.com/indcap.htm  and use the trial and error technique

[shawsofhell]

I was thinking of using this for the core: http://www.rsaustralia.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@1765726590.1091625558@@@@&BV_EngineID=ccceadcmefdkkejcfngcfkmdgkldfih.0&cacheID=auie&3269078412=3269078412&catoid=-84051016

and this for the wire: http://www.rsaustralia.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@1765726590.1091625558@@@@&BV_EngineID=ccceadcmefdkkejcfngcfkmdgkldfih.0&cacheID=auie&3269078480=3269078480&catoid=-77320036

do these seem suitable?

[R.G.]

1. What is the best type of core to use (material, diameter, height)?

3C8 ferrite material, ungapped pot core, about the size of the real ones, which vary, but are all about as small as are commercially available.

2. What gauge wire should I use?

Small enough to fit enough turns inside the (small) pot core. This turns out to be quite fine, on the order of AWG38 through AWG42 depending on the window area of the core.

3. Does anyone have any resources I should read or tips?

- Pot cores come with AsubL ratings; this is the inductance per turn squared that you get for that core. If you have a pot core with an Al rating of 100uH per turn squared and put ten turns on it, you get 100uH times 100 ( ten squared) turns squared, or 10 millihenries. One hundred turns on that core give you 100uH * 100t * 100 t = 1 henry. Manufacturers make the same physical sized pot core with a variety of Al ratings. Sometimes this will be stated as an inductance for a given number of turns; for instance, 10mH for 100 turns. To scale that to a different number of turns, you have to proportion on the square of the number of turns.
- You want 500mH (1/2 H), about 40-50 ohms of wiring resistance. You'll probably have several hundred turns of wire to get there. That's a guess.
- When you get it like you like it, pot the inductor by dunking it in a can of spar varnish and letting it dry for several weeks. That will protect the fragile windings and wires.

[chumpito]

http://home.t-online.de/home/micro.wave/inductor.html

http://www.fnrf.science.cmu.ac.th/theory/magnets/Producing%20wound%20components.html

[shawsofhell]

Shouldn't I want the resistance as low as possible?

Oh and does anyone think that I could use the core I linked to further up the page?

[Paul Perry (Frostwave)]

Shouldn't I want the resistance as low as possible?

Oh and does anyone think that I could use the core I linked to further up the page?

Yes, but you don't need it zero!
And that core would be a good place to start.
If you can work out how many turns, then you can work out the max diameter wire you can use.

[R.G.]

To extend Paul's comment, and mine -

Go whup a hunnert turns a' waaahr (as we call it in Texas) on the core, measure the inductance you get, then calculate the number of turns you need to get to half a Henry.

Then calculate the wire diameter as the square root of window area of the core/bobbin divided by the number of turns. This gives you the biggest wire diameter (including insulation) that will fit. Then drop it a wire size or so to get a practical wind.

[Lonestarjohnny]

Sound's like a cool project But CE Distribution has the Vintage and a Brighter sounding Fazel for cheap if your lookin to buy 1
Johnny

[Athin]

how is it with winding - you wind it one way right (elsewize the EM fields generated would cancel each other out) go back to the beginning and wind again in the same direction, right?
(the winding would be like from left to right go back to left, from left to right, is that OK?) the same goes to winding trannies - correct?

[Paul Perry (Frostwave)]

how is it with winding - you wind it one way right ?

Yeah, just keep winding, in one direction (doesn't matter which!).

[swt]

If it's only science project, you can try what i do. use old radio ferrite, cut it, or get it in different sizes, and different wire gauges,and wind it  with taps at different resistances. I have got really good sounding inductors, with 1.00 mm wire gauge, and low resistance, and interesting results, with awg42 too. The only inherent porblem is noise, because it's an open design, it might pic radio, interference, etc. but it can be shielded using a copper box or paper. If you decide to build something like this, let me know of your experiences, and we can share data and results, maybe we can get to a decent diy inductor to share with the community...