col

Making the driver very narrow will compromise it's performance. Having a driver with its own permanent magnetic field so close to a pickup will change the sound of the pickup noticeably because it will significantly alter the shape of it's magnetic field. Moving the pickup further from the neck to allow space for the driver will also alter the sound of the pickup.

None of the info on the sustainer ideas thread will tell you how to have neck and bridge pickup that can both work with a sustainer driver. Its pretty much pickup at bridge with sustainer driver at the neck. Pete's 'piggy back' idea is neat if you want to keep the neck pickup, although you won't be able to have sustain on when using the neck pickup. It works by having the driver and neck pickup share a permanent magnetic field. I think that this will have minimal impact on the sound of the neck pickup, assuming you can modify it to make room for a thin coil to stack on top (not easy with some pickup designs).

You didn't say what style, or whether you can pay or need free, so: Toby Walker does live skype lessons (I havn't used this service, but he is a good player - check him on youtube). Stefan Grossman has free youtube samples (whole song lessons) from guitar workshop dvd's. Guitar workshop tutorial videos can be bought as digital downloads from their website. Matthieu Brandt has a great website with lots of great stuff, he also has some great tutorial vids on This is a good jazz guitar site with lots of stuff to learn. For rock and pop type stuff, youtube has millions of useful clips that will keep you going for years. Best thing to start is get a guitar and some guitar music you like, then try to work out what the notes are. Try to meet guitar players and ask them to show you stuff. Get a good book (one that you can understand) that has some music theory for gutarists in it. Cheers Col

No problem. If you are getting some sustain on the lower strings, then a buffer is likely to help - it will prevent 'tone sucking' ie. roll off of higher frequencies due to the input of the circuit loading(whatever that means) the guitars pickups.

Gotta disagree there. The reason Pete's design works is because through an extensive process of trial and error, he homed in on a set of specifications that provide suitable electrical performance: The wire Pete specifies when wound to 8ohms around a suitable(!) core will produce a coil with an inductance value within a suitable range. The combination of this Inductance and DC resistance mean that the Impedance of the coil is fairly linear over the guitars frequency spectrum - only rising considerably at the point where you are playing higher up the neck so sustain is easier to generate (strings closer to driver, driver closer to belly of notes standing wave) The combination of output cap coil inductance and resistance generate a low Q resonant peak at or close to the frequency of the open high e string - the most difficult string to energize. the low inductance of the coil combined with the value of the output cap provide a phase relationship linear enough that phase lock can be achieved between driver and pickup without wasting too much power (assuming that you drive circuits phase response is compatible - big assumption). As far as build quality of the coil - yes that is crucial, but has nothing to do with the reason the design is successful. Any system of any design for any purpose needs to be manufactured to a reasonable standard or it won't work. Assuming the coil is reasonably well made, the really important factors in getting Pete's design to work are - the combination of core material and winding wire give you an inductance close to the inductance Pete gets (whatever that is). The circuit you use has similar phase response to the circuit Pete uses (whatever... you get it). So there are some unknowns that cannot be solved other than by trial and error. try using different core materials, different magnets etc. Try a different circuit - it may have a more suitable phase response... mustn't forget that the guitars setup - action, strings, pickup - can have a big impact on success. The main thing is though, that if you're in the ballpark, you will get some sustain on some strings - even with a slightly shoddy coil, a fetzer/ruby, and a non-ideal core (The difficulty is getting from there to a nice system with a strong even response and reasonable battery consumption.) So I'm thinking that there is something more fundamental wrong with the Sabudum's project. cheers Col

8.8 ohms is a touch high, but you should still get some sustain on some of the strings, so I think the main problem is elsewhere. more questions: Are you sure you have the magnet positioned correctly - ie. with the poles vertically in line with the driver core? If you have accidentally put it at 90degrees, it will not work. Are you testing the driver by holding it in your hand as close to the strings as possible without touching ? Try it near the 12th fret - it will sustain more easily there. Have you tried reversing the polarity of the driver? Either reverse the connections, or turn the magnet over Once you have checked these out, the next thing is to suspect that there is a problem with your drive circuit, or the connection between it and the driver coil - e.g. are you sure all the caps - in particular the output coupling cap - are the right way round (correct polarity)? Double check that all the components have the correct value. swap out the LM386 for a new one (you did use a socket?).. etc. If you have a breadboard/plugboard, build a new version of the circuit on the breadboard to see if you get the same results. cheers Col

You need to measure the actual resistance of the actual coil with a multimeter. Theory is great for designing stuff, it can tell you what should happen, but when the thing doesn't work, you need actual real world measurements to tell you what did happen. Measuring the coil's resistance will tell you if there is a short somewhere, or maybe if there is damage causing a much higher resistance.

there's 113 turns to the coil, in order to have 8 ohms impedance The resistance is 1.378 ohms and resistance per meter is 0.549 ohms/meter Which resistance is 1.378 ohms? that should be fine. I'm concerned about the resistance. with Pete's design of drive coil, the impedance at low frequencies is dominated by DC resistance, so DC resistance needs to be about 8ohms. if its a lot lower, it could cause the LM386 to fry, or go into shutdown protection (if it has that?). Where is the 1.378 ohms figure from? cheers Col

how many turns on the coil? what is the dc resistance of the coil? how is the magnet attached to the core?

You say you used a single coil dual blade pickup - this doesn't make sense. Do you mean a single coil 'sized' humbucker that actually has two coils? or a single coil pickup that has a strange dual bladed core? If it's a single coil driver, then winding to Pete's specs should have given you some definite sustain action - even if not ideal. There should be something to work with. If it was a 'rails' humbucker style with two coils, then it is very important how you connect the coils. Assuming the pickup used the standard humbucker approach of a single bar magnet, at the bottom between the two rails, then the coils need to be wired out of phase with each other, so that they push and pull at the same time. If you wire them in phase, one will push while the other pulls == no sustain ! Whether you wire them in series or parallel is also important - if you would each coil to 4 ohm nominal impedence, you should wire them in series, if you would them to 16ohm each, then wire them in parallel (If you would them to 8 ohms, then oops!... I recommend wiring them in parallel and wiring a 4 ohm half watt resistor in front of them to bring the overall impedance up to around 8ohm). As has been suggested by everyone else, you need to post some photos and details of the specs of your driver. The wire gauge you used for the coil(s), number of turns, DC resistance of coils, how they are wired, the more detail the better. good luck Col

Recently got my hands on a scope. My circuit as is has a problem with parasitic oscillation on the virtual ground. To fix this I swapped out the LM324 quad op-amp with a TL074cn. The LM324 cannot sink enough current at it's output to provide a stable virtual ground, the TL074cn seems ok. TL074cn might not be the best chip for the job - it was just what I had in my box - I guess any that can handle 40mA at the output will do. FWIW, this fix didn't have any noticable effect on the functionality! It worked fine with the oscillations (they were at about 1Mhz). Might improve the efficiency a little, but I doubt it as most of the juice is used by the LM386 which doesn't use the virtual ground. cheers Col

LOL :-D awesome clip forget AGC and bi-lateral drivers, all we need are two hydrocoptic marzel veins and a drawn reciprocation dingle arm !

that extra 4 ohms will be significant! DC resistance is only part of the story, a more important parameter is impedance, which in the case of a sustainer is a combination of DC resistance, capacative reactance and inductive reactance. The problem is that most folks don't have the kit to measure the inductance (from which impedance can be calculated), so we go with a DC resistance reading. The capacitance is easy to adjust - just tweak the output cap. The reason why the baseline driver spec works is because the coil inductance, resistance and the output capacitor together form an LRC circuit in which the resonant frequency is near that of the open high E string - the most difficult to drive. Additionally, the bandwidth of this circuit is in the region of 1000kHz - exactly what we need to cover most of the guitars range. look here http://www.calctool.org/CALC/eng/electronics/RLC_circuit here's another really good calculator: http://pr.erau.edu/~newmana/imped.html plug in a resistance, capacitance and inductance, and this one gives you overall impedance, and phase shift ! If you change any of these parameters, you will have to find other ways of tailoring the drive to match the response of the guitar to the sustainer. Ok here's the point to all this babble your extra DC resistance equates to about 50% more turns than the required spec (either for Pete's coil or the twin coil I use). Inductance increases with the square of the number of turns, so if ~126 turns would have given you 8ohms and an inductance of around 1.2mH (assuming the correct wire guage and a suitable core), 190 turns would give around 2.7mH, Plugging 12 ohms and 2.7 mH into the first calculator, the resonant frequency is now about 220, and more importantly, the bandwidth is reduced to 700Hz (If you reduce the DC resistance to 8ohm and keep the inductance at 2.7, the bandwidth is reduced further) The resonant frequency can be corrected by switching from a 220u cap to a 100u, but the bandwidth is not so easily sorted! To demonstrate the effect of the reduced bandwidtch, lets use the second calculator I linked to to look at the impedance at the extremes of the range we are interested in ie. 82Hz and 1000Hz: with a 220u cap, 8 ohm and 1.2mH: the impedance at 82 Hz is 11.5ohms and the phase shift is -45 degrees the impedance at 1000 Hz is 10.5ohms and the phase shift is 40.5 degrees with a 100u cap (better match for 2.7 mH), 12 ohm and 2.7mH: the impedance at 82 Hz is 21.65ohms and the phase shift is -56 degrees the impedance at 1000 Hz is 19.5ohms and the phase shift is 52 degrees (at ~300 Hz, both have an impedance of close to their DC resistance, and phase shift close to zero) So you can see that in addition to your extra 4 DC ohms, the extra inductance, pushes the impedance up dramatically at the edges of the required frequency range - beyond what an LM386 can effectively drive. The phase distortion is also worse meaning that less of the energy getting to the strings is actually helping drive them, due to the phase shift. Anyway, enough. My point is that the difference in number of coil turns can make a significant difference to the success of the device. hmm, it almost sounds as though something is broken - a bad solder joint, or some fault in the coil ? It shouldn't be that sensitive to 'fiddling', and it shouldn't jump between not working at all and working quite well... anyhow, keep at it do you have a breadboard ? if not get one, they are not expensive, and make circuit tweaking MUCH more practical. Col

thats great. good luck. do you have a breadboard to build it on first ?

The specs are pretty much: .23mm wire wound to ~4ohm on each coil. steel/iron cores. cores 2mm thick, 10mm deep 56mm long (could have been a bit shorter... but that would alter the inductance for that DC resistance, so stick with 56mm for now) coils were wound to give as near to a square cross section to the wire bundles as possible to maximize magnetic coupling, so they are ~3mm thick and wide (4mm would work as well for sure. there is 1mm of core above the top level of the coils. the wiring as I said is series. And, although I'm not sure if they are in or out of phase, that is something you could test after construction - keep your options open. here's the driver up close and personal: http://i100.photobucket.com/albums/m15/col_012/angleddrivercloseup2.jpg and here's the circuit with a pick for scale http://i100.photobucket.com/albums/m15/col_012/toviewwithplectrum.jpg If you just want a working sustainer, you would be better buying a commercial unit. cheers Col