NickLabs Posted October 4, 2006 Report Share Posted October 4, 2006 quote [i could've sworn earlier someone just took a computer speaker and ran it to a screw wound about 20 times with thick guage wire, and that managed to sustain one string. My idea is to put something like that in my guitar, with a retractable wire that ran out of the guitar and do e-bow type stuff, then retract it back into the guitar to the point where it just look like a screw sitting there. (there would also need to be an on/off switch of course). Then I could do e-bow type stuff without having to pick it up and put it down during live stuff. (plus I think it would look really cool). I also like the e-bow idea because you don't have to adjust it like some of the sustainers created by people on this thread. quote If thats possible that would be awesome! could some of you sustainer experts comment on this please? Link to comment Share on other sites More sharing options...
ebenezer shred Posted October 4, 2006 Report Share Posted October 4, 2006 ^yeah i would really like to know if i could do this too. Link to comment Share on other sites More sharing options...
psw Posted October 4, 2006 Author Report Share Posted October 4, 2006 okokok...but it's 6am in the morning here...just a little more sleep ok? pete Link to comment Share on other sites More sharing options...
col Posted October 4, 2006 Report Share Posted October 4, 2006 quote [i could've sworn earlier someone just took a computer speaker and ran it to a screw wound about 20 times with thick guage wire, and that managed to sustain one string. My idea is to put something like that in my guitar, with a retractable wire that ran out of the guitar and do e-bow type stuff, then retract it back into the guitar to the point where it just look like a screw sitting there. (there would also need to be an on/off switch of course). Then I could do e-bow type stuff without having to pick it up and put it down during live stuff. (plus I think it would look really cool). I also like the e-bow idea because you don't have to adjust it like some of the sustainers created by people on this thread. quote If thats possible that would be awesome! could some of you sustainer experts comment on this please? Hmm, its a pretty vague description... Without amplification, it won't do anything, so I'll assume that the idea is to take the output from the amp for a set of pc speakers and instead of connecting it to one of the speakers, connect it to the screw coil ? If this is the intention, I guess that the amp won't last long 20 turns of thick wire will be a _VERY_ low impedence - enough to fry most small amp chips I fear. Anyway whatever the intention, a screw and 20 turns of 'thick' wire is unlikely to give you the results you would want . With that setup I would be surprised and happy to get any reaction at all.... better would be to build a thin driver coil and an LM386 amp - at least you will get something usable out of it. (or make a hand held single string version - same principal, but probably easier constuction...) Good luck Col Link to comment Share on other sites More sharing options...
psw Posted October 4, 2006 Author Report Share Posted October 4, 2006 Ok guys...infusing coffee now... My idea is to put something like that in my guitar, with a retractable wire that ran out of the guitar and do e-bow type stuff, then retract it back into the guitar to the point where it just look like a screw sitting there. (there would also need to be an on/off switch of course). Then I could do e-bow type stuff without having to pick it up and put it down during live stuff. (plus I think it would look really cool). I also like the e-bow idea because you don't have to adjust it like some of the sustainers created by people on this thread. If thats possible that would be awesome! could some of you sustainer experts comment on this please? I thought so too, and did a bit of work on something like this...there may even be something too it, but nothing like as simple as you are thinking (more like a miniture ebow...hint, hint) Anyway...you can do something like this but for a live instrument....unless you are heavily into noise rock or something, perhaps not very practical Now...my very early experiments here (page 2 I think) I built a simple coil. It was wound with thinner wire as I recall to 8 ohms on a 4mmx5mm ferite slud with paper bobin sides amking a disc 1cm round and 5mm deep. On to this I attached a very small (5mmx1mm) rare earth magnet. I then ran this from a very simple amp (just the LM386 with output cap initially...but this will load the pickups so you will need something like the ruby, really) and held it above the strings near the neck with the bridge only selected...the strings almost jump off of the guitar...startling!!! However...get anywhere near, or even point the thing towards the selected pickup and you will get ear piercing shreicks of feedback (think mic at a loudspeaker squeel). Now if space rock is your thing, and you like playing on the edge...a bit of echo and a gentle hand and you can control those feedback oscillations into a very convincing Theramin sound...but one false move and the audience goes deaf...hmmmm So...I actually would encourage this. There are some interesting effects of such a coil on the pickups including toal temporary neutralization....interesting... But if you were to go this far, you may as well build a normal driver coil (just as easy to do really) and you will need a similar amp anyway. A screw by itself will not do it, unless you add a magnet to it. On the question of the speaker...One really cool effect...and again I would encourage this is the "power slide" . Take the ruby and run it as a practice amp, make really long speaker leads and use the back of the shiny speaker (like a mini interanal computer speaker) on the strings. The vibration of the speaker itself will vibrate the strings infinitely, very powerfully and to great effect. Makes a bit of a racket, but if you play loud enough, who would know. Works even better if you take out the cone and stick a coil on the voice coil (more vibration) but it does suffer the same EMI effects...get to close to the pickups and squeeeeeeellllllll...ek! Another approach is to try and vibrate the entire instrument (check out the sustainiac Model C...do they still make this)...basically a speaker/vibrator that attaches to the headstock to vibrate the whole instrument...dubbed acoustic sustain by the Manic Boys...looks a bit wierd though, may make your playing hands go numb... I did look at different ways to doing this myself for quite some time. I tried making a bridge that had piezo elements that were intended to mechanically vibrate the strings (no EMI, no visible driver, etc) but they just don't have the power. Other ideas tried was to vibrate the whole trem assembly in a strat...EMI problems though... For those who cant help themselves, you can attach all kinds of things to the output of the amp...LED's light when you play (looks cool, no useful effect) and tiny electric motors will run backwards and forwards with the signal's wave (but not fast enough...) So...not entirely practical. The easierst way to try this is to buy some wire and wind it around a round fridge magnet (not a screw) to 8 ohms (a fair few turns) and run it from a little battery powered practice amp (like the ruby). One neat thing is that if you flip it over, you get the harmonic effect... There may be a way to do something as you describe and I had a good idea for it...but not really DIY. The above is an early version of one of the elements that lead to the hex driver stuff. It is 10mmx5mmx5mm so very small but can drive a string over that black dot. It could also be used as a pickup with preamplification. The combination of the two therefore, effectively makes a tiny ebow!!! I had considered such a pair with a docking station (containing the circuit and battery) where the player could pull it out, just as you suggested, and use it as a kind of "stealth" ebow. In this way it would not even have to be connected to the guitar at all (has an internal pickup remember), just to the circuit so could be potentially mounted on a strap say. Without giving too much away...later hex elements had a different approach for even less EMI than this one. One of the interesting effects was that if misaligned, it would go between no sustain, normal sustain and harmonic sustain. If I were to use this type of thing in such a device...the harmonic effect could be created, and the sensitivity of the sustain, could be regulated by the angle at which the device were held above the strings...so just a flip of the wrist...hehehehe Sounds good, eh...maybe I soulda done that instead.... In the end though...the sustainer is about as hard to do as any of these if not easier. You still need coils of wie, magnets and amps. It could be that people are a little confused that in the last 15-20 pages we are exploring advanced developments of the sustainer devices (AGC circuits, Rail drivers, etc) but don't let that put you off. The device does work as a simple coil and amp...but it does take patience and a little skill to get the driver just right... Hope that helps, and gets you all thinking a little...it is a simple device, but there are quirks...that is why it is intriguing and attracting so much time and attention... pete ahh more coffee... 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psw Posted October 4, 2006 Author Report Share Posted October 4, 2006 Alright, I think I did this ok... Strings damped about 20-21mA Flat out Sustain about 100-102mA or so it would seem...battery could be a little fresher... As could I...but I am getting better, thanks for your wishes... In many ways your circuit concept may be superior in performance, and lower in battery consumption, as well as being adjustable to achieve these kinds of effects too (a different more useful "sensitivity" control perhaps). Anyway...hope this adds a little to the hard data and encourages you further. At 200x amplification, you'd expect a bit of power to be drawn. Perhaps, as always it seems, the secret is in the driver. The commercial drivers do seem to mimic the size and shape of a conventional pickup in all it's incarnations...I think ultimately the rewards will be found by thinking outside of these "limitations", even if I do seem married myself to the concept of a pickup/driver for practical purposes. I also hope the coil winding ideas provides some food for thought and further encouragement to deal with the driver technology... pete ps... I also put up a link to that German forum and if we have visitors from over there Willkommen (ok...so that's the extent of my German language abilities) OK...so I woke up this morning, and suddenly realized that I tested the battery consumption above with the guitars volume control turned off!!! The guitar will of course sustain if the volume is turned off, but it does seem to have an effect (there is a 250K resistor bridging the input instead of 0 when turned up) even though the input to the sustainer circuit comes directly from the pickup before the controls (another reason for a buffer!) The results were the same, but the effect was far more powerful (it will even vibrate the strings with the guitar upside down and the strings dampened by my knee under the weight of the guitar itself!!!). If you have the guitar so as "no" sound is produced the thing runs at 20mA...as the strings self vibrate, this will rise fairly rapidly as the guitar gets louder to 100mA. The strings vibrate plenty strong enough though with the thing drawing about 40-60mA, but as I have no gain control, it just keeps driving and consuming power. Now the thing is, I think you do need the power to get the thing to do that (run from no sound) but if picked, the note is already in motion so doesn't need such a kick, if a low note similarly and, after a certain point, the gain (and power consumption) coulkd be seen to be a little excessive...hahaha So...this bodes well for col's approach, but I think there may be another way (if I only knew enough practical electronics). What should also be noted is that my guitar is doing this without the EMI issues and signal degradation even though a very simple driver design and with all this power applied...makes you wonder... pete Link to comment Share on other sites More sharing options...
onelastgoodbye Posted October 4, 2006 Report Share Posted October 4, 2006 Here's some pics that should thoroughly explain my jig: the white bits are just plastic sheet, same thickness as the core, and notched so the core fits in there the bottom bobbin is pushed into the mounting block, the core slides into the bobbin >> here the top bobbin clamps onto the top 2 mm of the core ,then the coil can be wound >> here the side clamps are screwed into the mounting block and compress the coil. here's a shot of that (with the top bobbin removed >> here I like your jigamathingie, psw. One problem i've been having with mine is that the coil ever so slightly pushes the bobbins apart while winding, which creates a small gap between the face of the bobbin and the bottom side clamping pieces. Then, when everything is clamped together, some windings get stuck in that gap...not good! Your paper trick might come in handy there. I also have an idea to replace the screws in your design, simplifying it even more, will test that tomorrow. Yep, a sign of good product design is that it can be made cheaply and with wide manufacturing tolerences - and still work... quite right! we called it a 'robust' design in school. Say Col, you're not an industrial designer by any chance? Tim Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 I like your jigamathingie, psw. One problem i've been having with mine is that the coil ever so slightly pushes the bobbins apart while winding, which creates a small gap between the face of the bobbin and the bottom side clamping pieces. Then, when everything is clamped together, some windings get stuck in that gap...not good! Your paper trick might come in handy there. I also have an idea to replace the screws in your design, simplifying it even more, will test that tomorrow. Ok...that was the intention of posting it...improvement (not sure how to do away with the screws...maybe some super high powered miniture rare earth mags and steel pieces would do the trick! ) Yes...the paper will help fill the gaps like a gasket and stop that happening, but you still want to make the core acurate so that it doesn't push through. The bolts and washers should avoid any rising of the coil. The side pieces will have to be thinner than the core to allow for the paper and the excess glue should push out the ends. BTW, when I say paper, I'm thinking something a little stronger than average paper...thin card more like, or art paper...something that won't tear too easily, especially when wet and is a little absorbant too. (I was a bookbinder btw) The intention of my jig is a little different. It is to make effective coils for a range of designs and allow for flexability in the core material and other construction aspects. The end result is a stable and highly effective potted coil from a very simple jig. The whole driver could later be encapsulated with epoxy. It would be important that there be no vibration, not only in the coil windings but the core itself...or even the mounting of the driver to the guitar itself. For instance...you could fill the core space with powdered iron (or ferrite?), saturate with CA glue and apply a magnet underneath to align the iron particles...if you wanted to get all high tech.... Yep, a sign of good product design is that it can be made cheaply and with wide manufacturing tolerences - and still work... Well yes...this project could adopt that as it's motto! quite right! we called it a 'robust' design in school. Say Col, you're not an industrial designer by any chance? I love it when you speak in terminology Tim... pete By the way...of the few things I do recognise in german...that thread is still looking into the need to have magnetic cores. I wish I could get through the language barrier to help them a little more...obviously we have discussed these things from time to time... Link to comment Share on other sites More sharing options...
spazzyone Posted October 5, 2006 Report Share Posted October 5, 2006 (edited) hey Pete are you trying to learn german? if not try that forum this way http://translate.google.com/translate?u=ht...Flanguage_tools look under guitar/bass its the first post Edited October 5, 2006 by spazzyone Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 hey Pete are you trying to learn german? hahaha....no, no But once I translate what they say and then those programs translate what I say...who knows what I have said...sometimes my english ain't too crash hot, crikey!!! pete Link to comment Share on other sites More sharing options...
ebenezer shred Posted October 5, 2006 Report Share Posted October 5, 2006 PSW, that "tiny e-bow" is exactly what I've been looking for!!! I know it's probably just as difficult as a sustainer, i would love to experiment with somethings like this, but i have some question. So, I would only need a ruby right? (not a fetzer/ruby), and how far away from the string did you put it to get it to sustain? What guage wire did you use to wrap the little magnet? Would i need the amp controls? How many wraps did it take? Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 WARNING...notoriously long, stream of consiousness post coming Pretty cool idea isn't it...however, two things 1) There may be a way to do something as you describe and I had a good idea for it...but not really DIY. 2) Long time followers of this thread will be aware that I spent a lot of time in the "wilderness" excercising my madness by following the dream of a completely different driving system...the Hex drivers. (over a year!) Here is an actual picture of one being tested... As they developed I even put lights in them and Tim/onelastgoodbye and emre did some stunning realizations of what could be... Ah...those were the days.... These types of things really generated a lot of interest and really did work in their own way...much as a few may have disputed it...but we were running before we could walk... So...of all the things on this thread, the only secrets are how these little things work, and how they are made. There have been clues to it, and I have had it verified by sending one to the USA...but only I really have one and they would be very hard to reverse engineer (the stuff it is made of and holds it all together is also the secret to how it works)... I would therefore have to kill you if I told you, so I won't. It would be unlikely that you could replicate it anyway and I may still have a use for the technology...but I fear not in a conventional sustainer system. The thin driver theories and other things came directly from this work though. That is why my designs don't follow conventional pickup like sizes and such. These very small drivers and their unique very strong balanced magnetic field, and the material that held them together, even the casing (of aluminium) for heat sinking...were all important elements in their design and function. Their faults are that they are very directional in a peculiar way. I fear that even describing the symptoms may give a little too much away of how they work. Let us just say they needed to be carefully aligned. The most imediate problem there then is string bending. As they have very good EMI reducing qualities (but not perhaps good enough...nothing will be perfect in that regard) they would have to be mounted close to and perfectly aligned at the bridge. I did get one working there in a fashion...but at the bridge saddles themselves the vibration of the string is zero...so just forward of that does not give a lot to work with...and you are practically on the bridge pickup... ------- Anyway...back on track. The miniature ebow thing came to me in testing these devices by holding them above the string. I realized that like a conventional driver, they could also operate as a pickup. I did a little testing and it is possible that such an ebow would work...and it did work with a signal from the bridge pickup. My ex-wife still has in her custody (for now) 100 of the electronic components that are essential to their construction (along with everything else) so in time, I may well build such a device. It is definitely a possibility, but how practical a one I do not know. I really like the elegant simplicity of the ebow but it is quite large and interferes with technique. It is also monophonic effectively. The casing is vital to the design...it needs to ride along parallel strings driving the one beneath, very close. It is not simply a matter of waving the thing at the strings. As a playing instrument, some kind of sustainer probably still has an edge and is easier to build. It was not until that last post that I ever really fleshed out the concept of what it could become...it does sound cool doesn't it. But it would take a little more development and probably wouldn't ever be a practical DIY project. Remember...you not only need an amp and driver (as with a sustainer) but a pickup too. Then there is the "shape" of the thing...the ergonomics that makes the device practical. If in the end the ebow is the best size and shape for what it does and how it must be used...then no amount of minituraization is really an improvement. ------ To finish of the sustainer thread history lesson... At one point I was getting so frustrated and I had moved so far away from the notion of a DIY sustainer (even though I was DIYing, no one else could)...and goaded by some who suggested the whole thread was a fake (well the lights in the HEX may have killed it...some though the LED's made it go!!!)...I put the basic principles of the hex drivers into a more conventional DIY format...the thin driver. The results were good right off the bat and the pickup/driver followed very shortly afterwards and has been working well (and nearly everyday) since. ----- The future as I see it... Where we are at now is that there is a practical, tested and unique DIY sustainer design...the thin driver. What is going on lately is some very interesting circuit refinements from col and some interesting ideas for a new, EMIbucking driver designs...the next generation of DIY driver design. What I would like to se is a definitive circuit and installation and driver construction method for the basic ideas of a DIY sustainer. I will...as soon as I am able...be doing just that, and may even be offering materials, circuits and such to make the project, in it's basic form, more approachable. Personally I'd like to make a mid pickup driver which would retain the use of both the bridge and neck pickups and simplify installation in the process (at least for strat style guitars). This would require an improvement in the EMI qualities of the basic driver. The rail/HB idea is only one (probably an important one) in achieving this aim. I'd also like to see an improvement in polyphonic response. ----- As for the Hex technology...if I had the means I would have already tested the "wave driver" principle. This would be a further development and have 12 tiny drivers with the intention of making a driver thin enough to surface mount between pickup on a two HB guitar and realize something like Tim's remote box concepts. The signal would likely come from the output jack of the guitar and be toatally non permanent. The wave driver concept (and that is all it is at present) would use all the principles of the Hex system for low EMI (but overcome the "alignment" issues). Circuit refinements like col's would also make the device much more approachable. At some point I will prove to myself if it can be done...however... Such "far out" thinking needs to be matched with a lot of experimentation and frustration. It would never be a DIY thing. Without some significant incentive, after already "wasteing" a year on the hex things...what would be the point of developing such a thing. ----- I think the real work is to be done with far more conventional approaches and I think that as far as that goes, we are on the right track. I, unfortunately, will have to ride the coat tails of others doing the hard yards of actually building these things, for the time being. I still have a few ideas left in me too, and I hope that I can contribute to the next stage of the development of this thing. As I was saying in a recent post, this thing is very simple in principle, the ideas are very attractive, the posibilities tantalizingly close...but it is trickier to move it forward than it would appear. I hope though that recent forward thinking discusions, even posts like this, will not hamper people from actually getting involved with making working versions of the current DIY technology. Perhpas it is time for me to post some more recordings of my guitar and learn more about what could be done with it. I must say, that vids and clips I have heard from the commercial units on their sites (fernandes I think) are a bit uninspiring. I think we could do better. It is one thing to be able to do something (and this is a builders site) but another thing to be able to do something with what you do...if you follow me! And then...there is more to life than sustainers. I had also some interesting ideas for bridge designs to allow multiple tunings. I think there is the possibility of some interesting pickup designs, perhaps combining the sustainer ideas too. Of course...there's still my personal life to sort out, lawyers to pay, guitars to play, children to raise!!! post out... pete Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 ok...enough of the rambling... a quick post before sleep... I have been messing with the FEMM on some of this stuff...and I think I have something of interest. Due to it being a little difficult to transfer the FEMM plots to jpeg to post just now (will have to wait for the pretty pictures...) Basically I modeled my driver vs the rail version. There is a significant outward stray fields eminating from the sides of the rails (towards the pickups) as opposed to the single blade/polarity which is attracted in towards itself (kind of circular)...in a conventional rail design... There is significantly less upward projection of magnetic power as the blades are attracted to themselves...this will be clearer in the plots... The conventional rail/HB design is a magnet with a blade at each polarity making a horseshoe magnet in effect, as you will recall... I did try a few other things (tri blade anyone)...but nothing there... What is of interest is the effect of multiple magnets in the cores of the coils in a rail design. This significantly alters the magnetic field. The field is much more contained with no outward projection and far more upward projection of magnetic energy. Such a design has other benefits too, as Tim has demonstrated in his bobbinless, epoxy, internal magnet design...that I am still very impressed with. The problem will be how to make such a design with conventional magnets and such and still retain features like small size, thin cores, etc. I can see some ways to do it...but will this take it out of the reach of the average DIY'er? There may be other ways of arranging it, I'll have to sleep on it... The upshot is that two coils with their own magnetic fields (flipped over with respect to one another) will operate independantly because the lines of magnetism can not cross. Like the single coil then, the magnetic fields will be drawn to their won magnets poles, not to that of the opposite blade...or across the gap of the horseshoe arrangement. Now...this is not a solution, but an observation. It could be that the independant fields will result in an effective wide core. It could be that the independent magnetic fields, when in proximity to other pickups will result in undesirable cross talk no better than a single coil design. There are a lot more to explore... I thought I'd share it with you now because I was a little startled at the difference between the two arrangements make. Still...never trust a FEMM, eh ...pics to come, that should make it clearer and give some food for thought and discussion... pete Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 Alright...perhaps I need a little more sleep...here are a few pics of the difference...this may need a bit more thought... The top is a regular rail, the bottom separate mags. Same drawings (but in the second the blades are magnetic and the old mag now "air") You can see that although there are no "stray" projections, as in the top pics horizontal lines outward and more energy at the poles of each of the paired magnets, less energy "wasted" (or is it simply contained...hmmm) within the first arrangement... The implication may be that far more powerful magnets could be used in the conventional way (very easy to do) to get more projection over the gap (in the top pic). It may be that things would be different again if those blades in the second pic were a realistic, thin (say 3mm) size...I'll look into that...It could be nothing but something to try...to no real benefit...hmmm Time for sleep...I knew there was a reason I don't turn to the FEMM these days... still...seemed to have worked out how to Jpeg it on the fly, so that's good... pete Link to comment Share on other sites More sharing options...
col Posted October 5, 2006 Report Share Posted October 5, 2006 Alright, I think I did this ok... Strings damped about 20-21mA Flat out Sustain about 100-102mA... Those figures are roughly what I expected - except the strings damped seems a little high... prebably realted to the huge gain you are using in your pre-amp... 100mA x 9v = 0.9watts which is getting close to the limit for a LM386N-1 into 8ohm... ...results were the same, but the effect was far more powerful (it will even vibrate the strings with the guitar upside down and the strings dampened by my knee under the weight of the guitar itself!!!). If you have the guitar so as "no" sound is produced the thing runs at 20mA...as the strings self vibrate, this will rise fairly rapidly as the guitar gets louder to 100mA. The strings vibrate plenty strong enough though with the thing drawing about 40-60mA, but as I have no gain control, it just keeps driving and consuming power. Now the thing is, I think you do need the power to get the thing to do that (run from no sound) but if picked, the note is already in motion so doesn't need such a kick, if a low note similarly and, after a certain point, the gain (and power consumption) could be seen to be a little excessive...hahaha Makes me want to do a subjective comparison between the basic un-teathered system and my experimental AGC similarities: Great fun Very responsive, can (very)quickly bloom to harmonics from no sound if strings are undamped. Can be used in fundamental, harmonic and 'mixed' modes. Similar roblems with EMI feedback and parasitic transformer crosstalk Differences: AGC version has considerably improved battery consumption - between 2 and 5 times AGC more susceptible to parasitic transformer crosstalk (this is possibly because at times it applies much higher gains) AGC system seems better at controlling EMI feedback (however, the biggest imprevement here comes from a dual core driver) AGC version seems a little more processed when playing very softly and allowing notes/harmonics to bloom. (in this situation, it is more responsive (very quick), and seems a little like a compressor because the feedback is so controlled - really good, but different) AGC version has much better balance over the whole neck. When playing hard/fast, non-Agc version can have an effect on response and tone - damping some harmonics and accentuating others. AGC version only takes effect when the notes start to decay, so it is less intrusive in those playing situations. I feel that some players may not like the more controlled effect of the AGC as much in some situations. Others will love the fact that it is non-intrusive in normal rhythm playing... With a crunchy or distorted tone both are great. For crystal clean tone, the AGC is too noisy (at this time IMO) - unless the AGC is turned down so much that its not really doing its job. This may be outweighed by battery consumption and string balance depending on playing style..... I think there may be another way (if I only knew enough practical electronics). Theres always another way the basic concept that I have used for this circuit could be applied using the LCD/LDR technique, or the JFET as voltage controlled resistor technique, there may be benefits and problems with each of these approaches... neither would be considerably worse or better (assuming a good design and no additional circuitry - like squelch, phase adjustment etc.) What should also be noted is that my guitar is doing this without the EMI issues and signal degradation even though a very simple driver design and with all this power applied...makes you wonder... It should also be noted that I first built a non-agc system with a single coil slim driver, and found the string balance and battery consumption to be unacceptable, this setup also had crosstalk noise, so it may be that my guitar/strings/pickup combination is more sensitive to these issues, and that an AGC system with your guitar/pickups would be much cleaner... that would be interesting to try... I have a lots of things to try out in order to better understand the nature of the crosstalk - first of all I need to work out if the guitar strings are involved, so I need to rig up a test. Will do that asap and report back cheers Col Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 an AGC system with your guitar/pickups would be much cleaner... that would be interesting to try... You sold me.... I think some of the driver issues can be addressed... Oh man...wait till I get my stuff back...I even have a few optocoupler chips...these may have some kind of application here... this is so frustrating.... p Link to comment Share on other sites More sharing options...
spazzyone Posted October 5, 2006 Report Share Posted October 5, 2006 Pete ill try to test that idea by placing seperate magnets on the outside of each blade instead of a central one running between the blades and while my rail is a conventional pickup not a driver i should see differant results......good or bad and also send me a PM with a shipping address so i can send you one of these as its time for some parts ordering for a freinds guitar so ill lump one or two extra pickups in it Now for a question to anyone that can answer it for me why would i get both modes at the same time? reversing phase seems to make no change...i get the same results and its random all over the fretboard except the 12th fret up on D.B.G.E wich are all harmonic im running the setup like this out from guitar into a spliter box then one output to a digitech RP6 then to guitar amp the other to the P.A amp. from that back to the rail and when i switch the pos/neg its the same would switching it going into the P.A change it maybe ? id rather ask before i hack up my cables or anything else for that matter Link to comment Share on other sites More sharing options...
col Posted October 5, 2006 Report Share Posted October 5, 2006 I think some of the driver issues can be addressed... Undoubtedly. The big problem (and it really is a biggie) in terms of tweaking and perfecting the driver is that the materials we are using are bits and pieces of magnets and metal that we don't have data for. To really tweak the driver in a controlled way and 'design' it for maximum efficiency and minimum noise, we need to be able to specify the magnetic properties of the steel/iron, and of the permanent magnets. We also need to be able to get magnets to our specifications in order to get much much further. We need to know the characteristics of saturation, hysteresis, magnetic permittance(can't remember the real term for this) etc. It doesn't take much playing around with Femm to see that these properties are at least as important as the winding wire guage. e.g. I have hacked up some femm diagrams of a nice simple way to focus the flux at the top of the double core driver... but even just small changes in dimensions and properties of the materials can make a big difference to the result. fwiw, i'm also thinking about whether it would be worth building a 'cage' to try and contain stray flux and keep it in a magnetic circuit much closer to the driver... not sure if this would help a lot, a little, or not at all. But without better knowledge of materials data it would be really difficult to know why it didn't or did work. It may be that the difference in crosstalk between your setup and mine is completely tied up with the materials and dimensions of the driver core and permanent magnet - we just don't have a clue Considering that the basic slim driver design can easily handle signals upwards of 120 - 150 mA, and the AGC system can function perfectly well at below 25mA, it may be that with better control over materials, we could reduce the size of the driver and at the same time make it more efficient and less noisy. Without having to resort to esoteric coil-less tech.... Col Link to comment Share on other sites More sharing options...
col Posted October 5, 2006 Report Share Posted October 5, 2006 ...Now for a question to anyone that can answer it for me why would i get both modes at the same time? reversing phase seems to make no change...i get the same results and its random all over the fretboard except the 12th fret up on D.B.G.E wich are all harmonic im running the setup like this out from guitar into a spliter box then one output to a digitech RP6 then to guitar amp the other to the P.A amp. from that back to the rail and when i switch the pos/neg its the same would switching it going into the P.A change it maybe ? id rather ask before i hack up my cables or anything else for that matter I'll take a guess Phase distortion. Your setup involves sending the signal through a bunch of circuitry between the pickup and driver that was never intended for the purpose. Do you know what the phase response of your splitter/P.A./rail driver combo is ? Quite possible that the power amp produces more phase distortion than the fetzer/Ruby, and that the rail pickup produces much more than the low impedence thin driver. If the total is getting near 90º within the frequency range of the guitar, then that would make both fundamental and harmonic mode produce a similar response, much as you describe. as for solutions: fancy phase correction circuitry different driver and/or amp or the marketing mans favourite - decide that it's a 'feature' rather than an issue Col Link to comment Share on other sites More sharing options...
col Posted October 5, 2006 Report Share Posted October 5, 2006 @pete I have a suggestion related to Femm. In order to really see if there will be more, less or similar interaction depending on differend arrangements of magnets, I htink it will be necessary to model not only the driver, but in the same 'space' the pickup ! You may see a different result entirely. I tried a rail with one magnet and a rail with one per core, and the field lines from the two magnet version were attracted to the pickup while the lines radiating from the centre of the 1 magnet version were repelled by the pickup. Unfortunately, it doesn't matter if these lines are attracted or repelled - either is bad and will cause crosstalk as an alternating signal is applied to the coil(s). Fortunately, the radiated flux is very weak. I reckon that our target is not going to be eliminating this stray flux, but reducing it by designing a more efficient magnetic circuit for the driver. Possibly with the addition of a flux 'conduit' shield. Another thing to be aware of when using Femm is that the pictures mean very little without the 'key'. The mapping of the colours to flux density (or whatever it is) is normalised for each model you analyse, so weak green in one pic may be 5 times stronger than the same weak green in another... I'm not sure if you can change this to force a particular colour mapping... another thing will be, if the strings turn out to be important in crosstalk, they will have to be included in any useful model - which is very tricky for femm, being 2d. I'm looking at a couple of 3d magnet FEA tools, but one is buggy, and the other is tricky (need to use scripts - ok for me, but generally less accessible. This may alow os to create more useful models at least of the PM and SM materials if not the coil. Something I believe may be important with regards to crosstalk is saturation of the core material, if the core becomes easily saturated and can not hold any more magnetic enery, does this mean flux is more likely to escape from the circuit - particularly with a nice chunky pickup magnet near by ? The cores I have would be very susceptible to this I fear - thin iron/steel non-laminated. Does using a magnet as the core eliminate this issue or exacerbate it? I guess it depends on the dimensions of the magnet and the material it's made of. Of course the biggest issue with using magnetic cores is supply - if the idea here is a system that folks can easily construct for themselves, it must not rely on parts that have to be salvaged from exactly the right 1970s no-name cheapo soap-bar pickup from a junk shop Col Link to comment Share on other sites More sharing options...
onelastgoodbye Posted October 5, 2006 Report Share Posted October 5, 2006 (edited) A quick dirty test with psw's bobbinless, core-less, and...bolt-less driver jig: instead of the bolts, there's a metal wire looped through the holes were the bolts would go, and the bolt + nut pulls the wire ends together. I tried some old guitar stringsfor the wire, but they snapped.The wooden piece on top is to distribute the clamping force more evenly. I'd put a similar block in the bottom too. It clamps well, better than my original jig, it's dirt-cheap, and the real kicker is that you can use it for thin cores. right now the former blade is 3 x 3 mm, 2 x 2 should be possible. So there you go. BTW, when I say paper, I'm thinking something a little stronger than average paper...thin card more like, or art paper...something that won't tear too easily, especially when wet and is a little absorbant too. (I was a bookbinder btw) Do you know kraft-paper (it's german too ) ? the brown stuff they use for packaging. Should do the trick. Or you could always use dollar bills . they're cotton-based rather than cellulose-based. Much stronger than regular paper. I believe bibles are usually made of that stuff as well. I'm looking at a couple of 3d magnet FEA tools, but one is buggy, and the other is tricky (need to use scripts - ok for me, but generally less accessible. This may alow os to create more useful models at least of the PM and SM materials if not the coil. Are you looking at cad-based plugins? That would be right up my alley (starting my first job as cad-designer on Monday. yay). I see there's some really good plugins for proEngineer, like Ansys/Emag but I doubt I could easily obtain that. Tim Edited October 5, 2006 by onelastgoodbye Link to comment Share on other sites More sharing options...
col Posted October 5, 2006 Report Share Posted October 5, 2006 A quick dirty test with psw's bobbinless, core-less, and...bolt-less driver jig: ... instead of the bolts, there's a metal wire looped through the holes were the bolts would go, and the bolt + nut pulls the wire ends together. I tried some old guitar stringsfor the wire, but they snapped.The wooden piece on top is to distribute the clamping force more evenly. I'd put a similar block in the bottom too. It clamps well, better than my original jig, it's dirt-cheap, and the real kicker is that you can use it for thin cores. right now the former blade is 3 x 3 mm, 2 x 2 should be possible. So there you go. looks great - pretty simple as well (heh sods law that I'm going to move away from super thin cores for my next driver experiment). Is the plan to drill two small holes in the core former for the wire, or to use some sort of tubing for the wire to go through ? If you were to use tubing, the top and bottom would have to be rigid, and the tubing strong... BTW, when I say paper, I'm thinking something a little stronger than average paper...thin card more like, or art paper...something that won't tear too easily, especially when wet and is a little absorbant too. (I was a bookbinder btw) Do you know kraft-paper (it's german too ) ? the brown stuff they use for packaging. Should do the trick. Or you could always use dollar bills . they're cotton-based rather than cellulose-based. Much stronger than regular paper. I believe bibles are usually made of that stuff as well. There are also plastics that are very thin, and stiff enough so they can be creased and hold a shape... I guess loads of different consumer items have packaging that could be recycled for this purpose - (I'm thinking about something that epoxy won't stick to). I'm looking at a couple of 3d magnet FEA tools, but one is buggy, and the other is tricky (need to use scripts - ok for me, but generally less accessible. This may alow os to create more useful models at least of the PM and SM materials if not the coil. Are you looking at cad-based plugins? That would be right up my alley (starting my first job as cad-designer on Monday. yay). I see there's some really good plugins for proEngineer, like Ansys/Emag but I doubt I could easily obtain that. No, there's a gnu thing called gmsh... because of its gnu/academic history, it has a steep learning curve, and it's difficult to work out what it can do and how the other thing I was looking at is 'quickfield' which has a student version available for free download - this looked like a good bet, unfortunately, it crashed after a couple of minutes... (btw, I'm not an industrial designer - I'm an out of work programmer/ex fine artist) cheers Col Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 I reckon that our target is not going to be eliminating this stray flux, but reducing it by designing a more efficient magnetic circuit for the driver. Possibly with the addition of a flux 'conduit' shield. Yes...there is no way of eliminating magnetic radiation...correction, a completely closed system of material enough to absorb the energy fluctuation created by the coils in the magnetic field, could...but then you wouldn't want to... This is an electromagnetic driver (akin to a motor, or the movement of a speaker coil, or a solenoid) if there is no magnetic radiation, there would be no effect on the strings. Perhaps the mass/permanance of the core does play a role...compare the mass of the sustainiac core...but with this is a loss of speed.... With these FEMM drawings, and perhaps I was wrong to raise them again, it is so easy to misunderstand what they are indicating. The density of the lines and the shape of the field are the important aspects. But this is a static (2D at that) field...it is an indicator of what the coils are manipulating...and where those manipulations are going (creating the crosstalk)... What needs to be considered is not how strong a field is, but if it is sufficient to hold sway over the strings and yet not leak too much into other magnetic structures nearby...obviously the pickups...but also the metal strings themselves... (And, in what direction this leakage is in relation to the orientation of the coils in the pickup!) The "idea" of the thin driver is to make as compact as possible these fluctuations in as small an area as possible. The idea of the rail/HB is to also provide an equal counterating nearby fluctuation in the field...equalizing the thing out... So...the fact that there are is a magnetic field (regardless of strength, etc) does not imply crosstalk problems...a pickup is quite happy with any driver there, as long as it is not operating!!! It is the fluctuations, the effect of the coils on the magnetic field that is vital... The crosstalk is caused by magnetic field lines that go through both the core of the driver coil and of the pickup. This is how magnetic structures are coupled (as in a transformer). A field radiating at 90 degrees to it (such as the horizontal line in with the rail plot) will not have too much influence it would seem. Now...consider the bi-lateral design. There are magnetic fields attracted across the strings...the fluctuations caused by the coils (which move the strings) also move in this direction...a direction very different to that of the pickup coils. (The Hex designs used a different directional force again, and independant "balanced magnetic fields" to further enhance this effect...hence the "alignment problems though)... Similarly, the side coil idea is to have the orientation of the driver coils at right angles to the pickup coils. This is an intriguing idea that would be improved over the fernandes concept if it were to use thin closely spaced coils and blades (3). But it is a more radical solution and not imediately applicable to my pickup/driver focus, so I have not considered it for a while... After more sleep...I am inclined to like the rail design with it's essentially closed system a lot more...but the lines of magnetism are substantially at right angles to the coils that we are trying to manipulate them with. With two coils working in opposite directions, I am not sure (at this time of the morning) about the amount of movement these coils will be generating. In this regard, the independent magnets in each coil, have the lines running running through the coil and the core, and on both sides of each blade. I think this is going to be more efficient but over a wider area, and will this efficiency result in worse EMI? FEMM is a very limited tool for people like us...it can make the magnetic fields visible and hint at things...but that is all. For instance...I modeled a structure of 3 blades last night. The outer blades as in the rail with another blade between them. Although of the same material, the inner blade has the same properties to the magnetic field as air! It was equally magnetised both Nth and Sth and so appeared to have no magnetism at all...not what I was aiming for. Similarly, shielding can have little or no effect, or completely seal the escape of magnetic radiation...it has to get out for the device to work in the real world... As always...this kind of thinking is speculation, at least without experimentation. I don't believe there is a system that will eliminate EMI entirely....but there will be a way to eliminate it enough. We already have one...that of distance!!! The fact that it will work over the neck, sufficiently away from the pickup proves this. Now, how close can it go. Even up there, if we were to FEMM it at a sufficient resolution with the strings and the pickup scaled in it...there would be some interatction seen. The question is, how much (EMI reduction) is enough. I do think that for my driver and for the commercial units, the distance between the bridge pickup and the neck pickup position is enough. But, it could be better...and where's that mid-driver I want... So...let's turn this discussion into a little brainstorm before people return to experimenting... What strategies can be considered to limit the effects of EMI for this device... Efficiency...less power out, less EMI out. Also...number of overlapping windings, depth of coil, the type, size shape and material of the core...how do these aspects allow for achieving less with more? Size...small size, limits the size of the problem Shape...in particular, the shape of the magnetic fields, the intersection of the lines, the way a structure holds a field to itself...that kind of thing. Also, the pysical shape of the device. Direction...coils arranged at different angles to the coils of a pickup Cancellation...multiple coils that counterat the fluctuations of the other(s) Absorbstion...structures that encourage the flow of magnetism to itself over other magnetic structures Sheilding...structures that encourage the flow by the use of preferential (ie steel over air) materials to limit the spread of the magnetic fields. Non-magnetic driver/pickup...a piezo pickup system, by eliminating the magnetic structure of the pickup should eliminate crosstalk (someone try this on an electro acoustic for me). The converse...piezo driver does not seem to be possible without a lot of power...if then, BTW! Materials...what is the effect of different permeances, laminated, powdered, ferrite cores Construction...how it is made, distance of the coil from the core, distance of the coils from the strings Magnetic field...the shape, direction, power and internal attraction and leakage of the field. Taking particular note that it is the fluctuations in the field, not the field itself, that is of concern... Modifications and additions to this list is encouraged... ----- I really though would encourage people not to go too far down this track though, except for the interlectual exercise. It will result in spinning wheels I am afraid. For us, I thing the most progress will be made by fumbling around experimenting and building things to arrive at something good enough, from which further developments can be made. I fear the thread could return to a theory based, rather than practical based excercise. Beware...I am most guilty!!! ----- Of course the biggest issue with using magnetic cores is supply - if the idea here is a system that folks can easily construct for themselves, it must not rely on parts that have to be salvaged from exactly the right 1970s no-name cheapo soap-bar pickup from a junk shop This thread is about "sustainer Ideas" ...so I guess anything goes. Projects that spin out from it can be separately documented in Tutorials or other threads. This brings together the power of the internet to draw people from anywhere, with any background and skill sets, to speculate, experiment and investigate these types of devices. It has a DIY focus, because we have to do it ourselves...cause who else will (it is not going to be driven by market forces). I do hope that there will be a continuing of the "doing it" though, and from the two posts posted while writing this, clearly there is little fear of that.... ------ I just saw Tim's version of my jig....ah, now that is simple...will it work! Bolts less than 2mm thick are hard to come by (and the holes etc difficult to drill) and were the sticking point in my design. In a more production mode I would create a winder that clamped it together so it could spin within the clamp...but you'd want to be making a few to make that worth while! With this kind of jig, I do think that a variety of different coils could be made easily, and put to different uses to explore all the ideas above...quickly and cheaply (it is only really the cost of the wire after all). (starting my first job as cad-designer on Monday. yay) Fantastic...congratulations Tim pete looks great - pretty simple as well (heh sods law that I'm going to move away from super thin cores for my next driver experiment). Is the plan to drill two small holes in the core former for the wire, or to use some sort of tubing for the wire to go through ? You would need to make a former for the core and the wires go through that. The core former could be any depth and size so it should meet a range of needs. (In Tim's version though, you would have to cut those wires to get it apart...hmmm). The paper bobbin works ok with our driver wire because it is thick...I doubt that you could do pickup wire sizes like this at the number of turns required. Once our wire is bent into the coil shape, it tends to hold it's shape....just watch the tension and it should be ok! Link to comment Share on other sites More sharing options...
curtisa Posted October 5, 2006 Report Share Posted October 5, 2006 (edited) Hi psw (and everyone else) Just finished burning through all 120 pages of this monster thread, and got inspired enough along the way to build my own thin coil driver! I figured I'd join the discussion and contribute a few ideas and thoughts. My driver is the same stacked pickup/driver combo that Pete came up with back in circa post 45. The construction of my single coil pickup was a little bit different to yours though, in that the individual pole pieces were sunk into separate holes, whereas yours were sunk into a slot that ran the full width of the pickup. I actually removed the poles, cut a slot in the bobbin (effectively joining all the polepiece holes together) and inserted a new 3mm thick steel blade into the bobbin window. The blade top is curved to match the strings curvature. The top of the existing bobbin forms the bottom of the window for winding the driver coil, and so all I had to do was cut a new bobbin top to keep the windings from sliding off the end of the steel blade. I used a narrow piece of masking tape to insulate the winding wire from the steel blade as I wound it on. I found an easy way to keep the windings nice and tight as I was winding them on was to pass the enamelled wire between a pair of books and draw the wire between them as I wound. The weight of the books applies a bit of pressure to the wire as it comes off the spool without gripping it too much, keeping the wire nice and taut. For potting I used a version of Selleys Aquadhere that is rated for exterior use and heat resistant to 110 degrees C, applying it to the driver with a matchstick once every 10 turns. The whole thing was wrapped in electrical tape, and the wire ends tacked in place with a small dot of superglue. I baked the assembled driver in the oven for 30 minutes with the oven set to the lowest temperature it'd do (50 degrees C in my case) to accelerate the setting time of the PVA - I noticed that some of us here had trouble with the innermost layers of PVA not setting properly and staying soft. "Baking" our drivers may be a good solution to preventing this from happening. My driver ended up measuring slightly higher than most - 14ohms with 100 turns - but this still falls in the "usable" range for the LM386 IC. I guess the wire I used as a little thinner than the recommended 0.2mm - I just used a big roll of stuff I had lying around that looked like it'd do the job! Anyway, the thing works! Just using the bridge pickup on my guitar feeding the "Champ" circuit that Pete posted, and holding the driver in my hand over the 20th fret I had sustain on most strings in most positions, even harmonic mode works! No microphonics either, so the potting must have worked too. High-E refuses to budge, but it looks like we're all having (or had) some trouble moving the high E string. Next experiments will involve building a FET input preamp, like the Fetzer, to prevent loading the pickup signal and hopefully getting better performance yet. Some thoughts/ideas: I noticed in your prior posts that you changed the output cap of the LM386 circuit and got improoved high-E string response at the expense of the lower strings. The output cap and the driver coil itself forms a series LC resonant circuit, the centre frequency of which is governed by the values of inductance (the driver coil) and capacitance (the output cap) of the circuit. At the centre frequency of the resonant circuit the impedance of the coil and cap are equal and at a minimum, and current flow will be at a maximum. Maximum current equals maximum magnetic field in the driver and best efficiency at a particular frequency of operation. So by reducing the value of the cap you're shifting the resonant frequency higher, which is why you're getting improved high-E sustaining action at the expense of low strings. Making C even smaller shifts the resonant frequency higher which will eventually stop being of use as it travels higher in frequency beyond what the string will actually do. The other thing about resonant LC circuits is that they all have a "Q", which is the amount of peaking in the frequency response of the circuit. I am thinking that one of the reasons why some of us are getting better results with our drivers than others is that some of our driver/LM386 circuits have high Q's (very sharp, narrow response at the resonant frequency) while others have a much lower Q (wider, flatter peak at the resonant frequency). The amount of DC resistance in an LC circuit governs the degree of Q - more resistance = lower Q, less resistance = higher Q. In order to get maximum efficiency and even response from our drivers, we may have to find the best LCR trade-off somehow. The C bit is easy, just substitute different values of C in the output cap position of the LM386 circuit, as some of us have already tried. R and L are a little more tricky - R is determined by the DC resistance of the coil once it is wound on the bobbin (size of the wire and length), and L is primarily determined by the number of turns and the material that forms the coils' centre, be it magnets, steel, air, ferrite etc. The popping of the circuit when turning switches on and off (like the normal/harmonic or power on/off switches) could be reduced by adding large value resistors (say greater than a couple of meg ohms) across the poles of the switch. Pro recording gear uses this technique to prevent pops when throwing switches. One more thing that's worth considering before I stop rambling, I noticed that when I moved my driver back towards the bridge pickup I got squeal as I approached the neck pickup even when I was using the bidge pickup as the signal source. This circuit is obviously quite susceptable to inducing all sorts of EMI garbage into both the signal and earth conductors. I wonder if there is such a way to run the driver in a balanced 3-wire configuration (ie, the coil driven by two equal and opposite signals swinging around a centre point) to reduce the extraneous EMI generated by the driver? All professional audio equipment uses this technology to reduce unwanted induced noise picked up in cables from being amplified at the input of the next connected device. The LM386 circuit feeding a transformer with a centre-tapped secondary would give you a balanced output, but the driver would need to be specially wound to accomodate this. I wonder if the transformer in the Fernandes sustainer is performing some similar kind of balancing operation here? Enough rambling for now! Cheers, Curtis. Edited October 5, 2006 by curtisa Link to comment Share on other sites More sharing options...
psw Posted October 5, 2006 Author Report Share Posted October 5, 2006 (edited) Fantastic post...and welcome curtisa Yes...all you say is true and already adds that balanced signal to our brainstorming from the last post of mine! It is great that you got the thing to go so far. There is an improvement with the thing actually installed underthe strings as to holding it over the top. I did get the problem with the earth connectors and my switching required the disconnection of all but the bridge pickup completely to avoid such noise...though it wasn't squeeling as I recall. You are right about the Q and such. Although my lower output cap improved high string response, it is not at the sacrifice of the low strings sustaining...they simply sustain at an octave above their note. This is similar to the "mix" setting I believe on some units. It is a neat effect and can be heard on a lot of those sound clips if you listen carefully. (At some point I will make some test sounds of my guitar...promise) Great tips and thoughts... now...here's a FEMM of the split blade rail...hmmmm not quite what I was hoping for...but, their should be some of the side to side effect of the bilateral design and some effect of the "air" coil on controling the fluctuations in the field. We could also exploit some of what curtis was saying about the Q with different signals to each coil (eg changing output caps)...I still think it is worthy of further investigation....or not! The idea of the split coil was to induce some of the benefits of the bi-lateral design that has the fluctuations in the magnetic field transverse the strings and the orientation different to the coils in the pickup... I'm not sure as to what extent it would do that, may create some kind of torsion effect...hmmm pete Edited October 5, 2006 by psw Link to comment Share on other sites More sharing options...
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