Inductor recommendations

[Wild Zebra]

Hello, my next project is the modable wah at GGG, any inductor recommendations?  Or comments by anyone who has made one.

[brett]

Most people buy an inductor, but there are good reasons for winding your own.  You can go lower or higher than standard, and you learn how to calculate inductances.  The ferrite spindles or halos for taking the wire should be available at Mouser.

You can also use the primary winding in those little $2 1kCT:8ohm audio transformers.  They are surprisingly good, even if they aren't made to be 500mH.
cheers

[miqbal]

You can also use the primary winding in those little $2 1kCT:8ohm audio transformers.

Excuse me, Brett. What is the meaning of that "1kCT:8ohm"??
I always wonder about this.....

[jrc4558]

Primary winding impedance = 1Kohm Center Tapped; secondary impedance = 8ohm

[miqbal]

God bless you, Mr.Constantin

[yeeshkul]

that's brilliant idea to make my own inductor! is there any article on internet i can read beforehand? i mean what type of wire to use, any method to use drill for winding it up or any other thing to know

Jan

[brett]

Hi
you'll find the formulas on the internet, but here's the most basic one.

For cores rated in microHenries per turn (e.g. the Philips FX2250 bobbin gives 2.5uH/turn), the number of turns required = squareroot(target inductance(uH)/inductance per turn(uH)).

So for 500mH, you need 447 turns on an FX2250.  In this case, I'd say that 440 to 460 turns would be ok.
To keep such an inductor small, you'll need to use enamel wire of about 0.2mm thickness (maybe less).
cheers

[yeeshkul]

Thanks Brett, do i have to insulate/separate the layers of wires somehow or just wind them up on the spindle so they touch each other? Completely a silly question, but i have never seen an inductor from inside

[Wild Zebra]

The wire is coated with enamel so no need to worry about touching.  I wound a few pickups and I thought about winding an inductor.  Hmmm maybe I will.  I just have the board all ready to go so I kinda wanted to order a few and get it done.

[aron]

>For cores rated in microHenries per turn (e.g. the Philips FX2250 bobbin gives 2.5uH/turn), the number of turns required = squareroot(target inductance(uH)/inductance per turn(uH)).

Wait. So to decrease inductance, we remove some wire? Is this a mod than can be done to existing Dunlop inductors?

[s.r.v.]

wind your own halo:
http://www.smallbearelec.com/Detail.bok?no=368
or you could email don butler (tone man, you have to google it) and get a fulltone inductor

[miqbal]

Wait. So to decrease inductance, we remove some wire? Is this a mod than can be done to existing Dunlop inductors?

Yes, exactly. You can also use different type of core for different result of inductance. But don't know about the quality of the sound. 

[brett]

Hi

You can also use different type of core for different result of inductance.

Yeah.  It seems funny (strange) to me that winding inductors on ferrite or soft iron (or whatever) seems to give quite similar results, as long as the inductance is about 500mH.  This experience isn't consistent with people who seem to make minor changes and perceive big differences, or use different inductors and perceive big differences. It makes me wonder if there is a lot of variation around 500mH in some of these inductors.

For those that wish to experiment, there's some stories* around that a little permanent magnetization might add some mojo to wah inductors.  This is easily achieved with iron cores, as occur in those little audio transformers.  You could even run some DC current (a mA or two should be plenty) through the secondary of one of those to magnetize the core.  (*I'm not suggesting that there is any merit in these stories)

cheers

[amz-fx]

Wait. So to decrease inductance, we remove some wire? Is this a mod than can be done to existing Dunlop inductors?

Yes, just be careful if the wire is glued to the form.

regards, Jack

[yeeshkul]

guys does anyone have a Thomas Organ inductor at hand? I would like to get close to this one, i mean does it have a metal core? what kind of wire was used? what is the diameter od the core? what is the resistance of the wire (that may be important i guess).

[aron]

>Yes, just be careful if the wire is glued to the form.

I will check it, but I'd sure like to see/hear the difference between a Dunlop inductor that's a closer to 600mH vs. one that's spot on 500mH.

[Paul Marossy]

I'd sure like to see/hear the difference between a Dunlop inductor that's a closer to 600mH vs. one that's spot on 500mH.

I would also like to know!