Advice on winding my own multi tap inductors

i bought PCBs from gustav for franks "enhanced" pultec and the mid frequency pultec.
i'll be "rolling my own"  inductors because i am a cheap bastard.(money i save will go to more DIY)
i will be getting the cores used by this DIYer:

http://www.diygallery.de/DIYsites/inductor.html
i haven'tlooked for wire but i'll try to find some .3mmcoppr wire at mouser. any sugestions for brand, type,etc.
i dont think i'll have a problem coming up with a winder.
im looking more for tips on the winding process itself. also when finished should these inductors be potted or coated in any way?
any advice you'll think i'll need please chime in.
thanks

What kind of core? Ferrite is easiest to calculate number of turns I'd guess. The wire he used is much thicker than the original, guess that doesn't matter to you (maybe you want a higher Q like it says in the link).  Doesn't matter I guess, better to get something done and working so you can get on with your life. Anyway, not much help, but you can get small rolls of wire from ebay. The stuff in the link is 30 AWG, a bit smaller than .3mm, which will give you slightly higher DCR for the same length of wire, but that's probably a good thing, considering the one in the link you showed had only 2 Ohms DCR. 

btw, I think in the pultec inductor thread people were using 34 AWG wire, if that matters.

http://cgi.ebay.com/Copper-Magnet-Wire-AWG-30-1-600-Ft-Red-Solderable-/160443901761?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item255b33a741#ht_1630wt_849

good luck with this, let us know how it ends up!

"What kind of core"

link says,"manifer 196 ferrite"
i'm not familiar with the different cores and their sonic qualities but it seems,ioaudio, cinemag and Don-audio are all using ferrite cores. the author of the above tutorial has tried some other cores and found these ones sonically pleasing. so i decided to trust his opinion. these "look like" the same cores ioaudio is using and will fit the PCBs i'm using.

"The wire he used is much thicker than the original, guess that doesn't matter to you (maybe you want a higher Q like it says in the link)."

not sure... should it matter to me? what are the sonic implications,higher Q vs. lower Q?
i'm not building a pultec, just a pultec "like"  EQ. this wiil be my first(only) hardware EQ so im looking for some color from this build.

"pultec inductor thread people"

not sure who you mean but id like to see this thread. i'll do search and check meta.
thanks for the input. gives me things to think about and  raises some new questions(questions,always a good thing)

amidon

is a company that sells cores and magnet wire

they have some charts on their site that help you determine wire size/turns: a given core : a target H
no minimum qty.

http://www.groupdiy.com/index.php?topic=14093.msg167242#msg167242

alk509 hipped me to this

...hope he is enjoying his sabbatical from diy: he'll return;

over{?

Here is the thread, I think:
http://www.groupdiy.com/index.php?topic=25482.0

shabtek said:

amidon
they have some charts on their site that help you determine wire size/turns: a given core : a target H
no minimum qty.

Click to expand...

cool link!  Can't find the charts though.. am I blind?

sabbaticals... seems like quite a few people are disappearing...

https://www.amidoncorp.com/specs/2-43.PDF

#77 pot cores (on a silver platter )

a! I see it now, there's a little specifications link at the bottom... totally missed that! thanks!

sorry to hijack the threat but I'm pretty much in the same situation.
I need some inductors (no pultec though) and I'm on very tight budget so getting them of the shelf is not an option.
Furthermore, I think I will have to make them handwound since I don't have a winding machine.

Anyway, let's start with something very very basic...

If I need an inductor with (say) 5 taps, do I have to start winding 5 separate cores at the same time and solder each core at the desired inductance?
Or I just wind one core, solder it to the pin and then continue with a new core from that point?
I hope my description is not very confusing...

thanks
mike

by core you mean winding (the core is the metal part), and your second description seems correct. 

mitsos said:

by core you mean winding (the core is the metal part), and your second description seems correct. 

Click to expand...

yes, I mean the wire indeed. Sorry about that  :

So, that's the correct method, right? 

1) winding one wire until you reach the first desired inductance. Then cut the wire and solder it to the 1st tap.
2) then start winding  on top of the previous one, until the second tap.

thanks
mike

thanks for the links,comments and advice,it is all helpful.
mitsos..  did you see amidon has iron powder torroids!  dont know which one has closest specs to original pultec but seems worth it for some DIYer to look into. there seems to be enough info out there(web)to allow a close approximation of the original pultec inductor.

i have a simple ? about winding. warpie writes:

"1) winding one wire until you reach the first desired inductance. Then cut the wire and solder it to the 1st tap.
2) then start winding  on top of the previous one, until the second tap. "

maybe it is implied or understood but being ignorant i need some simple things spelled out for me.
after soldering to the first tap the wire for subsequent taps needs to be soldered to the first tap also,yes??
warpies post makes it sound like the wire floats . maybe this is obvious but like i said, being new to this i need confirmation.

no floating wires. and you don't have to cut the wire for the tap.
remove the coating, solder the tap, and wind further.

got it.
suspected as much but i know magnetic flux can be transfered without a direct connection and thought maybe this was the case here.
thanks

you want to do an inductor, not a transformer

thanks for making this clear and sorry for the confusion I caused 

mike

"don't have to cut the wire for the tap.
remove the coating, solder the tap, and wind further"

seems like this would be a good idea if one could be sure that the calculated number of turns was spot on. from what i've been reading this is usually not the case and some fine tuning is necessary to get the exact mH value.

how have those of you who have already wound your own inductors dealt with this?  

I'm in the same position as you guys.

I've been looking at the RM8 cores.  They have a screw lug which gives you some adjustment on the overall L.  It's also easy to get from RS in the UK.

The only thing I haven't been able to find is a data sheet like the one for the amidon cores, which gives you maximum possible inductance etc.  I'm trying to wind an inductor that is 1.4H & don't seem to be able to determine whether the RM8 core will go to such a high value.

heres the best place to get the info you need.

http://www.epcos.com/web/generator/Web/Sections/Contact/Page,locale=en.html

product inquery should do it

Rob Flinn said:

I'm in the same position as you guys.

I've been looking at the RM8 cores.  They have a screw lug which gives you some adjustment on the overall L.  It's also easy to get from RS in the UK.

The only thing I haven't been able to find is a data sheet like the one for the amidon cores, which gives you maximum possible inductance etc.  I'm trying to wind an inductor that is 1.4H & don't seem to be able to determine whether the RM8 core will go to such a high value.

Click to expand...

You have to calculate the number of turns, then calculate the cross section of the winding and determine what gauge wire you can use. Then you have to calculate the length of wire by multiplying the number of turns by the average turn length. Then you multply the length by the lineic resistivity (ohms-per-foot) to get the overall DC resistance. If the DCR is too high, you have to use a larger core or a higher AL.
You may also find that even the smallest gauge (I wouldn't use smaller than #42) doesn't fit in you core.
It is relatively easy but tedious to control the actual inductance. Usually, one slightly overwinds and measure, then reduce the number of turns until the inductance is correct. Caution: the core halves must be rubbed against each other and clamped to avoid any particles in the gap. That means you have to assemble and disassemble several times.

Abbey thanks for that info.  Are you saying that one has to buy a load of bobbins & just experiment to see if you can fit the number of turns required ? 
Also what is too high a d.c resistance considered to be ?