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  1. #31
    It's a combination of the current through the coils, coupled with the number of turns (ampere turns in fact). It's a fine balancing act at that too.

    Too many coil windings = too high an inductance, which means the coil presents resistance to higher frequencies feeding into it. The higher frequencies are the thinner strings, less ferrous material in them, so they actually need more drive

    Too few windings = not enough magnetic force presented at the strings...only way to compensate is to cranck the current up, but that saps the battery.

    Re round vs square coils. Square would be better (as it goes, I'd already considered them...in fact, you wouldn't believe the amount of McSpank Grey Matter processor 'cycles' I've dedicated to this little project!), but my simple coil winder (a drill chuck) cant cater for winding anything other than circular shapes! In fact longer rectangular coils would be better still...slightly overlapping one another so no dead spots when bending strings etc.

    Quote Originally Posted by Ross77 View Post
    Ah. I see. sounds like a good project.
    Is it the no.of turns and length of wire that makes it work? If so you could use a small square bobbin to reduce the wasted space between the coils and then you can drill them to suit the size of the magnet. no need for a fancy holder and hopfully reduce the height.
    Not sure I fully grasp what you're getting at when you say (re square bobbins) "drill them to suit the size of the magnet" nor how could this proposale "reduce the height" .....I'm all ears, could you put more meat on the bone?

  2. #32
    Not sure I fully grasp what you're getting at when you say (re square bobbins) "drill them to suit the size of the magnet" nor how could this proposale "reduce the height" .....I'm all ears, could you put more meat on the bone?
    I may have misunderstood, but I thought you said that the magnets were different sizes which was causing problems with holding them? If you use a square bobbin then it could easily be shaped to suit the magnet size (or epoxy the smaller ones)

    I was thinking of the small plastic box section that you get from model shops, if you cut to size and put a small bolt through with a washer on each end then you would have a former and be able to hold it in jacobs chuck......

    With regards to reducing height I meant that if the square section utilised the availble space better then it wouldnt have to be as tall...

    Is that better?

  3. #33
    All the magnets are the same size 5mm rod (which will be the core of the coil), this bad sketch i did for Dean helps visualize...




    (it's probably worth pointing out, that the above sketch was a simplified version of how it'll look....and only used for testing. The coils will not eventually be visible ...as I intend mounting them into some CNC milled perspex. The only bits you'll see arethe tips of the magnets protruding above the perspex holder)

  4. #34
    Did Dean sort you out?

    Will you be selling any of them? Im always keen to try new ideas, but havent got the time to make my own yet. Can you wind inductors for Wha's with that machine? Just replaced the inductor in my cheap wha with a halo and totally transfromed it.......

    Ive got a bit side tracked with this thread and just spent the last hour on Utube looking at pickup winding...

  5. #35
    Quote Originally Posted by Ross77 View Post
    Did Dean sort you out?

    Will you be selling any of them? Im always keen to try new ideas, but havent got the time to make my own yet. Can you wind inductors for Wha's with that machine? Just replaced the inductor in my cheap wha with a halo and totally transfromed it.......

    Ive got a bit side tracked with this thread and just spent the last hour on Utube looking at pickup winding...
    What's a Wha?!!

    Dean is up to his eyeballs - when he offered to help it was conditional that I wasn't in a hurry. I'm not (& remember he's doing this for free!).

    re selling them...this isn't a commercial venture...& to be honest, even if I wanted to sell them (which I can't imagine it being worthwhile!), there's still an awful lot of further experimentation done wrt the coils themselves (number of of turns, wire gauge, type of core material etc)....the final coil design is still some way off.

    I have no real proper coil winding facilities...just something I've put together myself "Blue Peter-esque! ....a 48V DC cooling fan, an encoder wheel striped disk (the pattern which I downloaded off the net, then printed onto a CD label & attached to a CD...I then cut out the middle of the CD & mounted on the fan!), a DC motor PWM speed control circuit (based on t he good old 555 timer!)....an optical pickup cct (to read the encoder disk) and most importantly a little bespoke PIC program that I wrote (which took me yonks as I hadn't a clue about PIC programming!). Previously I've been winding the coils onto small sewiing machine bobbins...but they're too big...hence the need for wanting to wind straight onto the magnets.
    Last edited by HankMcSpank; 24-06-2009 at 10:38 PM.

  6. #36
    What's a Wha?!!
    Wha wha pedal....(Wah Wah if your fussy)..........AKA voodoo chile intro
    Dont want to interfer, but if Dean gets mega busy then I could have a go.
    Just re-read the thread, sorry about the previous posts.

    Is this Idea limited to just sustain? if the coils where energised from a PIC then could some strange new effect be created? Ie just sustaining certain strings for a preset time.............:dance:

  7. #37
    Quote Originally Posted by Ross77 View Post
    Wha wha pedal....(Wah Wah if your fussy)..........AKA voodoo chile intro
    Dont want to interfer, but if Dean gets mega busy then I could have a go.
    Just re-read the thread, sorry about the previous posts.

    Is this Idea limited to just sustain? if the coils where energised from a PIC then could some strange new effect be created? Ie just sustaining certain strings for a preset time.............:dance:
    Yep Wah Wah is better (I'm fussy!).

    Do you know the spec of the inductors in the Wah Wah? In therory, I could probably wind such an inductor...but why? (are they hard to get or something unique about them?)

    I'm using a PIC in two places...

    1. For the coil winder itself (nothing to do with the sustainer!)...to count things like number of turns, traversal count etc (when to reverse the motor feeding the coppoer onto the coil)

    2. In the sustainer circuitry. A lot of folks use an analogue AGC (and a good AGC is what a sustainer needs), but that's a failry lo-tech inflexible approach & since I've just learned how to program PICS (that makes m an expert!), I'll be using the PIC for the AGC. Basically, it'll take sample of the dc rectified incoming guitarl (ie into the sustainer circuit rom the pickup)...based on the sampled incoming level it'll ether increase or decrease the signal at the power amp stage (feeding the sustainer coil). The PIC could also be used for clever switching (mainly powering stuff off when not in use as battery life is key), but I can't envisage actually adding an effect itself....PICs are actaully pretty feeble things processing wise.

  8. #38
    PICs are actaully pretty feeble things processing wise.
    And I thougth they were the answer to all processing problems, is the clock speed to slow?

    Do you know the spec of the inductors in the Wah Wah? In therory, I could probably wind such an inductor...but why? (are they hard to get or something unique about them?)
    No not hard to get but at 20 from the gud ol US its a bit pricey. 520mh is the magic value apparently. Read an article on old vintage Wah's and it seems that the sound is due to the magnetic build up of the pot core and suggested that an additional second winding could provide this varible magnatism (if that sounds correct) to recreate the sound?

    I know lots about guitars but electronics to that level is beond me...:heehee:

  9. #39
    Quote Originally Posted by Ross77 View Post
    And I thougth they were the answer to all processing problems, is the clock speed to slow?
    Yes...I think they go up to 20Mhz (though I just run mine at 4Mhz ....I'm placing modest processing requirements & higher clocks just results in more heat/consumption)

    Quote Originally Posted by Ross77 View Post
    No not hard to get but at 20 from the gud ol US its a bit pricey. 520mh is the magic value apparently. Read an article on old vintage Wah's and it seems that the sound is due to the magnetic build up of the pot core and suggested that an additional second winding could provide this varible magnatism (if that sounds correct) to recreate the sound?
    Well, i know a little about electronics...but inductance & the associated magnetism is something I've never had to apply a lot of thought too. (& is a specialist field in itself). i know the basics.

    As it goes, the single string sustainer coils I've wound are about 1mH ...520mH seems like a whacking big inductance (you sure you don't mean 520uH?) , but then there's the question of what type of core, wire gauge used blah blah (things get really esoteric when it comes to old vintage components!). Have you a link to the coils in question?

  10. #40
    As it goes, the single string sustainer coils I've wound are about 1mH ...520mH seems like a whacking big inductance (you sure you don't mean 520uH?) , but then there's the question of what type of core, wire gauge used blah blah (things get really esoteric when it comes to old vintage components!). Have you a link to the coils in question?
    Definatly 520mh

    http://geofex.com/Article_Folders/wahpedl/wahped.htm

    Its a few scrolls down. and easyier reading on the site....

    The best explanation I could come up with is this. The inductor in the classic wah setups carries the DC bias current for the first transistor. While this is only microamps, long exposure to this unidirectional bias could result in a remanent magnetization of the inductor core if the core material was not very good in the classical, linear EE sense. It's possible that Vox merely specified the circuit, the maker (Jen, I think, in Italy) made the early wahs from as inexpensive a material as they could, and the slight deviation from linearity resulted in a sound that the folks at Vox liked. That is - it was a happy accident resulting from being cheap. I've never heard another explanation that accounts for the differences. There are differences, and measurable ones, and ones that square with reasonable explanations for how the thing works and sounds. This legend's true.
    I have not seen or heard any of the supposed "next generation" Fasel style inductors, so I can't say whether they are true to the originals.
    One thing that became obvious is that you could artificially get a more linear core material to have an offset, and in the easiest way. If we're always pumping current through the inductor, we can get any offset we like by just pumping more. If we were to put a second winding on a wah inductor, we could force DC through it from a current source circuit, which would force the "center" of the magnetic operation toward one or the other saturation points. Of course, this is not possible with a pre-wound and potted wah inductor, but is emminently feasible if you happen to wind your own. It's even more feasible if the inductor you use happens to have a second winding, like the Radio Shack transformer that is mentioned later. This secondary can just be hooked up and current fed through it. I intend to do this as as soon as I get some bench time. Note that I've been saying "current source". You can't just use a resistor, because transformer action would reflect this resistance into the inductance winding as a load and damp the resonant action of the inductor. The minimum you need is a transistor connected as a current source to keep from doing this.
    Any help would be most appeciated.

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