curtisa

At this stage I'm curious to see what makes the "thick" driver so usable with sustainiac's systems, so I'll pursue that first before trying to thin it down further. The info I have suggests that 256 turns of 32AWG wire is used on each coil, and the measurements shown in that pictorial indicates around 4-6 ohms DC resistance per coil. Coupled with the patent info it appears that both coils are connected in parallel with the windings in phase with each other, giving a potential total resistance of <3ohms (!!). I assume that if the windings are the same direction, the magnets need to be in opposite polarity for the scheme to work properly. However... The switching class D amp they use keeps the frequency constant at roughly 30KHz, and reproduces audio frequency variations by PWM-ing the output signal. The inductive impedance at 30KHz is also going to be a lot higher than 3 ohms. I wonder if the very nature of a class-D amp makes it better suited to evening out frequency response variations and problems in our DIY versions because the applied frequency is constant and unwavering? Good suggestions, I'll try a few of those. Stewmac was only as an example, I'm sure there are many others. And like you say I can probably find some shitty single coils I can destroy from somewhere. Regarding the opening in the bobbin for the pole pieces, it'd be better if the bobbin had six individual holes rather than one continuous slot - when I make the cut I need to have something to keep the two half-bobbins from collapsing once it is split. You need a way to keep the powerpack voltage from "charging" the battery when applied. Regular batteries, as I'm sure you're aware, do not like being recharged. Perhaps when you have the extrnal supply plugged in you can use a 12V supply with some steering diodes installed so that a 9V battery is "blocked" when a higher voltage is applied? I think that's how it's done with lithium battery backup schemes in logic circuits - you could probably Google some schems...

So if I understand you correctly you're slicing the bobbin along its length, from bass to treble, and the two halves you end up with are the top plate plus half the bobbin, and the bottom plate plus half the bobbin? The two coils in that instance would then be wound in top of each other. Or maybe I'm misunderstanding here... I tried to get my hands on some plastic extrusions the last couple of days but couldn't get anywhere. I was really after a rectangular tube with a 5mm x 20mm window with the thinnest walls (around 1mm) I could find. The best prefab option I could find was a rectangular tube with a 5mm x 8mm "window" at 1mm wall thickness from a hobby shop made from styrene. At a plastics manufacturing shop they suggested they could build something out of 2mm acrylic sheet and make all the joins out of plastic welds, but 2mm sheet is probably too thick. I was thinking perhaps I could order something like this: http://www.stewmac.com/shop/Electronics,_p...ckup_Parts.html Cutting the bobbin vertically between the 3rd and 4th slug holes would give 2 (rough) bobbins. A bit of reshaping and cutting out a new rectangular window would give me something not unlike the two side-by-side bobbins shown in that sustainiac stealth dissection pictorial. Where do you get your magnets, Pete?

Dunno, that photo dissection shows the width of the laminations of the sustainiac driver core being about three-strings wide. Was considering using the good old exterior-grade PVA I used last time. My thinking was I'd wind a layer of wire on, brush a coat of PVA on, wind another layer, brush another coat etc... Maybe varnish as an alternative (layer of wire, brush a coat on, layer of wire etc)? How did you find working with that "glosscote" stuff I mentioned last year? Any good? I think you can get big uncut squares of pickguard material from the spare parts department of guitar stores. Try online?

Good animations Col. Just as a side note, the steel laminations from the transformer I'm cutting up are easy to do using a hacksaw. Nothing special there. I'm actually finding the middle leg of the "E" section is a more useful size - it's just a little bit wider than three strings, which will make it a good size for the dual-winding bilateral driver, I just have to cut the length down so that it's not too tall. The problem I'm seeing now is finding something that will make a nice neat bobbin out of. I was thinking of going down to the hobby shop and seeing if they had any plastic rectangular extrusions I could use. Any other suggestions?

On the contrary - I expect to require a lot less power to run it, or at least a lot more effecient use of the power we have now. I suspect that the loss in power from the transforming effect of the driver/pickup combo (depending on how the pickup winding is terminated), the solid un-laminated core of the driver (big eddy current losses), and the use of a linear power amp stages are big factors in the life of the battery and the effectiveness of the sustainer. Side note: I notice in the sustainiac patent that they use a feedback AGC topology, except they talk about current regulation of the driver itself, rather than voltage regulation of the input signal. Yes, there seem to be about 9 photos there in total, which is handy. The really interesting info is mainly in the thread itself - the number of turns on each coil, size of the magnets, size of the bobbin window, guage of wire etc. And comparing with the sustainiac patent you can even work out the correct way to connect the two coils. Handy note if anyone is interested in purusing this themselves: a couple of the photo's clearly show a copper foil shield around the bobbin assemblies that is obviously earthed as some form of electrostaic shielding. I can get bags of the copper foil from work - it's commonly used as a screening layer in industrial control cables, and when a cable is stripped to get to the inner conductors, several metres of the stuff is cut off and thrown away. I don't reckon you could get transformer laminations in anything other than commercial quantities (particularly something odd like just the "I" sections), but cheap mains transformers are probably good enough to tear into. You'd only need a dozen "I" sections at the most to build up the core, should be possible to build up several cores from the one transformer. Insulation between the lams needs to be maintained though - waxed paper or varnish would probably work nicely. Not sure how hard the material is to cut ("grain oriented silicon steel"?). I'll let you know when I get stuck into one myself Doing your own laminations is a possibility. The trick would be finding something thin enough the use (more lams per core width = less eddy current losses+higher inductance), and easy enough to cut cleanly without making daggy edges that short onto each other.

The socket you plug into needs to have a switched contact on it somewhere, so when the plug is inserted the two contacts are forced apart. That's how it's done on guitar amps with a channel footswitch jack that overrides the front panel channel switch. Any electronics store should stock them. Finding one with more than three poles is going to be trickier though. Regarding multi-pole plug/single cable options, Jaycar (and other electronics suppliers if you live elsewhere) stock 5-pin XLR plugs and sockets which are heavy-duty and locking, which may be another option worth considering. In other news, I'm seriously considering re-visting the whole installation of the sustainer again, primarily sparked by Pete's resurrection of an earlier quote in this massive thread - the one with the dissection of the sustainiac coil - and also because of the way I currently use my DIY sustainer guitar. With the DIY guitar I find that I almost never use the neck pickup by itself anymore (awful sounding pickup at best anyway), leading me to believe that perhaps I would've been better off building a dedicated driver rather than a combo driver/pickup with all its quirky switching and termination requirements. I'm still quite intrigued by the prospect of installing a dedicated driver in place of the single coil of my HSH Ibanez S470, a pickup that I personally wouldn't miss if substituted with a more useful item such as a sustainer. I think there's still a lot of things to experiment with in regards to driver construction that we've talked about, but never actually done anything with other than theorise - the dual-wound laminated core of the Stealth system in that photo dissection is just begging for some closer attention, and Sustainiac's patent has quite a lot of useful information regarding shielding and cross-coupling effects of the driver and surrounding pickups. As of today I start 4 weeks of annual leave from work, and I'm sincerely hoping to have a crack at fiddling with some of the ideas floating around in this thread during my holidays. I have some old transformers kicking around somewhere that I'm hoping to pull the laminations out of and build up some trial laminated driver cores with. Should be interesting...

What's wrong with using a signal transformer to isolate the driver signal? That's the easiest (and only!) way to fully isolate two AC circuit's earths.

You shouldn't need one. The difference between compressors, limiters, expanders and noise gates is all in the sidechain circuitry. By combining the functions of each sidechain circuit you can do the whole lot using one VCA element. That's how they do it in large format mixing consoles where each channel has it's own compressor/limiter/gate and VCA fader element - it's easier, cheaper and cleaner to use one VCA in each channel with multiple sidechains than have one VCA for each function.

This has been already touched upon some time back. The driver/pickup stack is essentially a transformer - the "primary" is the driver coil, the "secondary" is the pickup winding, the "core" of the transformer is the pole piece(s) of the pickup which the driver is wound on to. The transforming effect of the driver/pickup is just like a step-up transformer - the signal being pumped into the driver winding is stepped up by the pickup winding. Shorting the secondary of a power transformer will result in lots of current in the primary, low or no voltage on the secondary, and excess heating (and losses) in the windings, more than likely resulting in eventual destruction of the transformer. Shorting the pickup winding out while using the driver will affect the driver in some way, be it reduced output, strange frequency response, and/or all sorts of other unpredictable behaviours. It may be advantageous to terminate the pickup winding into some resistive load when in sustainer mode, rather than leave the pickup either fully shorted or fully open, maybe 100k or so. I found in my sustainer I had to short out the pickup winding because when the pickup leads were left open-circuit it would feedback really badly, presumably because I was stepping up the driver signal via the pickup and radiating all kinds of crap into the guitar cavity. But I'm pretty sure I could get a better sustaining action if the pickup winding wasn't shorted dead, maybe loaded just enough to be just under the point of feedback. I don't think shorting the pickup winding will result in destruction of the pickup (as for the power transformer) as the source impedance of the pickup winding is quite high and no damaging currents are likely to be flowing through the winding, but I do think that it may be better to run the unused winding into some load.

Short of replacing all the electronics in each bass so that they match (expensive I would guess, and still no guarantees that the tonality would remain comparable between each bass), or buying some special programmable preamp (also expensive), if you don't mind a bit of DIY you could make a bass switching box. I made one years ago for my singer/guitarist, and although his only selected between 2 inputs, there's no reason why you couldn't expand it to four. Think it only cost $40 or so in parts. You could have 1 input for each bass, each with it's own fixed level attenuator (or volume pot if you wanted to get fancy) and 1 output. Set the volume balance for each bass beforehand, say in rehearsal, and then when you need to change basses, sling the new one on and select the appropriate input on the selector. You could even do the whole thing in a floor box with a bit of ingenuity.

Don't think it will work. Diodes at the input will only clamp the input signal to +/- 0.6V (they're uniderctional), making the source of the clipping before the sustainer amp, not after. What you really need is something like was experimented with by Col and myself, some form of automatic gain control, something that reduces system gain if the signal is above a certain threshold and/or increases system gain if the signal is below the threshold. The driver signal needs to be clean and controlled, not harshly limited.

My pref is two separate options, the passive easy version and the active fancy version. Don't forget that those people with only two pickups and no coil tapping may only have small control cavities anyway, best not to waste any valuable space if you're also trying to squeeze the sustainer amp in aswell. Well, you could make the sustainer amp as a plugin daughterboard that sits on top of the switching board perhaps? That way you could make lots of sustainer amps on self-contained PCB's and provide them as-is with the passive-switched option, or as a module that plugs into/onto the active board for those that want it. I would think it's quite common - almost any pointy Ibanez/Jackson/Yamaha/BC Rich etc fitted with humbuckers and single coils will more than likely need it. Any dual HB/5-way switching guitar will need it. Anyone who has already modified their guitar with coil taps and phase reverses will need it. Not sure about that. A JFET may pass signal if it's configured as a shunt switching element (ie, shorting the signal line to earth), but I have a feeling that the gate and source would need to be tied to ground to do it, which would probably not work with your switched-negative scheme you're using now. Would have to experiment with it to find out more... Sorry about that. I did see your eariler request but completely forgot to follow it up. My guess is that you've either got the take-off point for the sustainer amp on the output of the volume pot, or you have the volume pot wired arse-about - wiper to pickup selector, bottom to earth, top to sustainer/output jack. Correct orientation should be top to pickup selector/sustainer, wiper to output jack, bottom to earth. My DIY version behaves exactly like yours should - sustain even with the guitar's volume wound all the way down. I don't know what kind of amp you're using but I assume you're actively buffering the input to the sustainer amp with something like a JFET source-follower or non-inverting opamp? The maximum input impedance into an LM386 is only 50K, which is far too low to be of any use in a guitar circuit for direct connection.

You may find that switching of the ground connection leaving the switch is unnecessary unless you encounter excess noise in the circuit due to ground loops. Experimentation will sort this out. Experimentation may also reveal that we need to short out unused pickups, aswell as disconnect them, in which case you might have to add more CMOS elements (or JFET switching if additional chips for 1 extra element is asking too much).

It may work quite well, and it'd reduce your CMOS count down to 2x 4053's - three elements to disconnect the pickup and put it in series mode, 2 elements to copletely bypass the pickup selector and it's ground, and 1 spare. Although IIRC the unused pickups (or at least the pickup with the driver attached to it) had to be removed from the circuit and shorted out because of all the unwanted interference generated by the driver/pickup combo. But then again, maybe you can use that 1 spare CMOS switching element to short out the neck pickup as a safety measure? If you ended up going down the PIC route you could even use it to synchronise the switching of everything to minimise pops - say PIC and CMOS switches on permanent supply (low current drain), when sustainer is turned on the PIC turns on the preamp with the output muted, switches the CMOS gates and then unmutes the sustainer output. Power-off sequence could be the reverse of this (or any combination you wanted to minimise unwanted noise). I suspect the layout will probably be one of the easiest things out of the whole development to achieve. If you went SMD and double-sided PCB, it should be pretty easy to shrink it down quite substantially.

Yeah, see previously edited post. I think it's fine. The only place I think it'll fall over is if there's any switching that involves shorting the bridge pickup to earth when selected to a different pickup, eg coil tapping a bridge bucker. With no switching of the hot lead of the bridge pickup you'll end up with no signal into the driver amp if the pickup selector is accidentally left in the neck or middle position. You'll need to make an allowance for it if you're looking to be as flexible as possible. My Ibanez RG7620 for example uses two humbuckers. The stock switching in it is 5-way - bridge humbucker, bridge coil tapped with neck coil tapped, bridge bucker with neck bucker, neck coils in parallel, neck bucker. Quite a lot of coil tapping going on in there. Your active switching diagram also doesn't allow for any situations where you might have HSH pickups with JEM switching - you need to maintain the ability for the standard 5-way selector switch to perform the necessary coil taps, and the only way I can see to do that is to add more CMOS switching elements. Of course if you're only looking at offering something that provides necessary switching options for specific guitars (SSS, HSS, HH) you could rationalise the number of CMOS gates and reduce the complexity even further. I figured that the system would retain the "mode switch" and "power switch". Whether they're implemented into push-pull pots or mini toggles or whatever I guess is up to the installer/designer. Provided the existing guitar doesn't need the fancy switching, then yes the passive option is probably the best. For more complicated schemes (Jem switching, the wierd 5-way switching in my RG), there's no way you're going to be able provide something that can be done passively - too many contacts required - unless the end user is prepared to sacrifice some switching options for the sake of the install. Yes, but you were talking about having a rotary encoder feeding a microcontroller providing all sorts of switching options. The active switching in itself can be made robust enough to keep most people out of trouble. It's the bit the user has to grab on to that will require careful selection. A Fender 5-way selector is a pretty robust switch and can be easily replaced. A digital rotary encoder is quite fragile, and replacement is neither cheap nor easy. Fragility can be countered by selection of more robust versions, but at the expense of...uhh...expense. Sounds to me like you need to breadboard some of these CMOS switches to find out exactly how much noise they introduce, and what you can get away with in terms of support circuitry.

Not sure that will work. In the "up" position I think the Neck pickup is floating with no ground reference - it'll buzz like a mofo. Edit: double-checked it and I think it's right actually. Nothing to see here... Haha! You've come up with something almost identical to me in the last half hour Although mine is intended more of an "anything" switching scheme. It pretty much sits inline with the pickup cables before any of the coil taps and pickup switching. I've shown 3 humbucker pickups, but really they could be any combination of pickups - SSS, HSS, HSH, SHH, HH, HS, SS etc...just make the appropriate connections and leave out the ones you don't want. Using CMOS switching it could be done with 3x 4053's. I think it's practical provided you have the space inside a guitar to fit it all in, and I think that will be a fairly big hurdle to overcome in any practical realisation of the sustainer as a retrofit kit, be it passive or active switched, one pickup or three - not everyone's guitars are blessed with a generous control cavity. I still don't see that as a problem - EMG's will go dead if the battery dies, basses with active pickups or preamps will go dead if the battery dies, Boss floor pedals will go dead if the battery dies. As long as the end user knows they have to check the battery before they hit the stage I don't see it as being an issue any more so than the other examples I've just given. Possibly, although you'd need to find a suitable rugged-ised solution for the control knob/button/switch - us guitarists are notoriously rough with our gear! Or at least an option that could easily, cheaply and quickly replace a broken one. Yes, it could do it, but perhaps carting-before-the-horse a little bit now

OK, I can see some ways of doing it actively involving a combination of SPST and SPDT switching elements. Let me have a think about it a little and I might be able to come up with something. I think with almost any active solution the user has to consider the fact that if the battery goes dead then nothing comes out - I don't see that as being any more of an issue than bass players do, or if your guitar is fitted with EMG's. I think if your design is intended to accommodate any pickup installation you have to be prepared to get quite complex in the implementation.

No, PIC's would only offer a solution to the controlling of the switching array, not actually provide a switch array in itself. PIC programming is something I do on a semi-regular basis, so if you decide to do something along that route I can provide some help if need be. I'm having trouble envisaging what exactly you're hoping to achieve with the switching - From my understanding I think all you want is to have the existing multi-way switch in any guitar available for normal duties (with coil taps if originally intended), and when you hit the sustainer switch it bypasses everything and goes straight to sustainer on/bridge pickup selected mode. Are we assuming that when in "on" mode the bridge pickup is used only as it's main function (ie single coil if single coil, normal un-tapped humbucker if humbucker)?

As far as passive switching goes, I can't think of a better idea than what you already have in that picture above, unless you consider using a bunch of DIP relays (still needs a DC power supply for the switching duties). As an alternative to the 4xxx CMOS switches, have you considered JFET switching? I built a talkback unit for a studio a few months back that had a soft-muting function for the talkback mike in the control room based on a single JFET switch. The unit was based on the first diagram on this page. A discrete JFET system could potentially be a lot more compact and flexible than the 4xxx CMOS chip schemes. You'd probably need to buffer the pickup signal entering the switching array, but that can be done with another JFET wired as a source-follower. And it'd probably work fine from the existing 9V battery supply in the guitar that powers the sustainer amp without resulting in too much extra battery drain.

"9x3"? Sorry, don't know what you mean by "3". The 12V plugpack will probably work fine with the circuits as-is, even with 3V more than you need.

You want the DIP version, that's what the PCB is designed to take. DIP = Dual In-line Package SMD = Surface Mount Device

Don't forget that the amp you're driving the sustainer with needs to have sufficiently high input impedance to prevent loading down the source pickup. That could be the reason why you're experiencing such a dull sound - the amp is loading down the pickup signal making it much more weak and muddy sounding. This will also affect the amp's ability to effectively drive the sustainer, which could account for your lack of sustain. With any circuitry designed to interface with a passive guitar signal there should always be some sort of buffering in place at the input of the amp, something with an input impedance >1M ohm will do. Simplest one I can think of is a JFET source follower run off the 9V sustainer amp battery supply. Maybe a buck or two of components. Google should turn up a few schematics.

Yeah, a 3 pole 3 way switch may be hard to find. 4 pole 3 way will work just as good, and give you a spare pole to play with, but I can't find either after a quick Google. I don't think you could modify an existing switch to fit another pole, probably more trouble than it's worth. A 5 position 4 pole switch is an idea you could try, you may be able to incorporate some alternative pickup combinations in the switching? With a little ingenuity you could possibly modify the 5 way switch to skip the 2nd and 4th positions to have it "operate" as a 3 way switch?

1N4001 is a diode type, and yes only conducts in one direction. Doesn't specifically have to be type 1N4001, there are many different types out there that will do the job just fine, but it should be a very common part to obtain. Yep, the diode is marked with a band at one end, which signifies the cathode of the diode. Schematically it equates with the "dash" at the end of the "triangle" Resistor value in ohms. Your switch has a number of wafers or poles which are independant from each other. Judging from the photo you've taken you've got a switch with two separate poles. In your case each pole contains one common connection (schematically the top of the arrow where it's marked "pickup selector switch"), and 3 position connections (each of the 3 little circles at/near the bottom of the arrow). You can imagine the switch as a pendulum hinged from the common connection, and "swinging" past the three position contacts as you move the switch. In your case it won't work with that switch as you only have a 2-pole/3-position switch - one pole for each pickup. You really need a 3-pole/3-position switch - one pole for each pickup, and a third one for the LED arrangement.

Something like this maybe? You'll need a spare wafer on your pickup selector switch to do it though.