Sustainer Ideas

[curtisa]

@Pete and Curtisa, I posted about the TDA7052 gain control ages ago (Dec 2006). There are two versions, one has the voltage controlled gain, one doesn't, unfortunately the more readily available one(here at least) is the one without gain control. I think it's the TDA7052A that has the control pin.

I knew there had been some discussion about a TDA7-something-or-another some time back, but I couldn't remember what the part number was exactly. Both the TDA7052A and B both have the DC volume port, it's the TDA7052 (no suffix) that doesn't have it.

The TDA7052A is available from Farnell.

[utopian isotope]

I've done some machining experiments on nylon, attempting to make bobbin templates out of it. Not worth an effort, since it is quite difficult material to work with,

unless you have access to cnc.

What I have in mind is to make a template, where you can wound coil(s), that has possibility to easily remove core(s), so that they can be re-used, when testing different coils.

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@psw: What materials do you use to make bobbins?

My suggestion is to use pc-board, since it isn't fragile as most plastics are. Solder pads are also much easier to make.

One major disadvantage is that you must use carbide bits(more expensive) for tooling, as pc-boards contain fiberglass, that wears hss quite fast.

Anyway, if there is other more suitable materials available for that purpose, let me know.

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In case of epoxy casting, mold(s) can be polished, so that it is easier to snap finished piece out of it.

I have two packs of epoxy for testing. Addition to polishing mold, I might test cooking oil, vaseline and motor oil...

But seriously taken, those who use polyester resin, use some kind of "removing liquid"(don't know the right phrase) for easier removal of finished piece out of mold. I once had bottle of that stuff, but it lost when I moved.

Edited March 14, 2008 by utopian isotope

[psw]

I've done some machining experiments on nylon, attempting to make bobbin templates out of it. Not worth an effort, since it is quite difficult material to work with,

unless you have access to cnc.

What I have in mind is to make a template, where you can wound coil(s), that has possibility to easily remove core(s), so that they can be re-used, when testing different coils.

----------------------------

@psw: What materials do you use to make bobbins?

My suggestion is to use pc-board, since it isn't fragile as most plastics are. Solder pads are also much easier to make.

One major disadvantage is that you must use carbide bits(more expensive) for tooling, as pc-boards contain fiberglass, that wears hss quite fast.

Anyway, if there is other more suitable materials available for that purpose, let me know.

AH...I was a little concerned IU that you had disappeared...

Bobbin making has always been a difficult thin for me as with everyone else. I have some skill and materials to do epoxy molding, but even there, the shape of a bobbin has proved very difficult to build in this way too!

PCB material is excellent, You could use perfboard (covered in tiny holes) and snap it to approximate size...then I use a bench grinder, sander to clean up the edges and round them...that is how I make neat vero circuits ...just don't inhale the dust.

I have also make things from reinforced cardboard...you could even design it on a computer and stick that with thin layers of card and glue with something stiff...perhaps even press it, making a kind of paper "wood"...if you vary the direction of the paper grain, it is even better, making it like very thin plywood with the shape printed out on it and cut to rough size with scissors before gluing up.

I've done some machining experiments on nylon, attempting to make bobbin templates out of it. Not worth an effort, since it is quite difficult material to work with,

unless you have access to cnc.

It took weeks to eventually make my one bobbin that can create my very thin driver coils that do not require any core or bobbin to self support...and a lot of money and time using it with different epoxies to get the desired result...again, not really a DIY proposition. Nylon is probably only worth while unless you have a design you know will work (or you are obsessively dedicated and this is the only way to make something to test a concept) and you want to make a lot of them. Nylon is also probably not the best for permanent bobbins. Better the ideas suggested above or modifying existing bobbins.

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im just wondering, is there an official schematic telling what goes to input and where the harmonic switch would go

or could someone just tell me?

Welcome back again zep...check the links below and also this page and software...DIY fever and layout creator sustainer page...come back with questions...there really isn't a definitive tutorial yet A little short on time right now!

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There are likely to be difference in the shape and 'throw' of the induced magnetic field.

Yes, this has been a problem for me with all multi coil driver designs. A design like I posted...

could benefit in this regard from neodyminium magnets. These can pack a lot of power into a very small space and so increase throw somewhat but be quite directional and so not necessarily pull excessively on the strings themselves.

I was messing with such ideas last night in front or the TV...sticking magnets to nuts and bolts and making chains and trying to sense relative attractions with a nail!!! I am very tempted to make it, but that would be a serious departure from the work I have been doing lately and opening up the whole hex design can of worms again...hmmm. It also may not (unless it worked in the mid position) help the switching problems either...and I would need to address the whole issue of mounting the device and avoiding unwanted interactions with like poled pickups that might be near it, and these alternating pole drivers. A bi-lateral may have similar problems with proximity.

I have even considered going down the sustainiac route and making some of my designs into active pickups without the passive secondary coils...another can of worms I suspect. One motivation for this is that I am playing a telecaster quite a bit now. The neck pickups on these are a little disappointing and I do wonder if an active version would be any worse. these are also 2 pickup designs, so perhaps an easier stepping stone than a 3 pickup guitar to mess with. Not a lot of control cavity space in there, but it would be a really interesting guitar to sustainer on, especially clean!

I have two guitars waiting in the wings for the device if solutions can be found. One is a strat with great pickups (SD and fender noiseless) and even has a battery and ultrra thin driver fitted and most of the switchs...just looking for appropriate solutions. The other is this telecaster with HB in the bridge and a khaler trem...this will be a very cool guitar if I ever finish it!!! This guitar will not accept my piggyback design on a tele neck pickup (I did try) so perhaps a dedicated driver is the only option. I am disappointed with the tele neck pickup, and I have considered routing for a mini HB or something...this brings up the idea of making an HB piggyback driver...hmmm.

Paralyzed by too many options, and not enough solutions. Also,m awaiting inspiration for you guys latest offerings...how's it going curtisa...

pete

[curtisa]

Also,m awaiting inspiration for you guys latest offerings...how's it going curtisa...

Still no real progress on the driver itself yet. Still waiting to find some magnets. Any thoughts on the small rare earth disc magnets that can be bought from Jaycar? I was thinking perhaps I could install one or two under each coil, and the circular shape of the magnets makes construction of retaining brackets much easier.

This afternoon I breadboarded up the driver circuitry from the sustainiac patent, just to see how it works. I don't have the appropriate MOSFET output devices, so I only made up the part of the amp shown on page 18 based around U3b (the HF oscillator), U3C/U3d (the MOSFET switch drivers), U5a (gate inverter) and U1b (driver input stage). The PWM action of this amp does work as is, although I've found that you need to take care that the input signal doesn't become too large otherwise you end up over-modulating the PWM signal, causing the outputs to latch up. Probably another reason to incorporate an AGC element in the design - A class D amp doesn't clip in the same way a linear LM386 does when overdriven.

U5a, C13 and R16 perform the anti-crossover functions that prevent the two output devices from being switched on at the same time, safeguarding against the destruction of the output MOSFET's by shorting out the supply. All it does is create an extra delay in the switching waveform for the upper MOSFET element so that is cut off before the switching of the lower MOSFET element commences.

Measured current draw with no input signal when running (but obviously with no load connected) was 4mA @ 9V. Switching frequency was actually closer to 28KHz with the components given, but near enough is close enough. The switching frequency can be increased by reducing the value of C12, although I don't really know if there's any benefits/drawbacks from doing so with this particular design.

[utopian isotope]

When workin with epoxy, I've noticed that by warming it with hot air makes it more liquid, so that bubbles disappear easier. Suitable amount of heat is when epoxy changes from blurry to more glossy.

Maybe that works on casting too?

Edited March 15, 2008 by utopian isotope

[psw]

When workin with epoxy, I've noticed that by warming it with hot air makes it more liquid, so that bubbles disappear easier. Suitable amount of heat is when epoxy changes from blurry to more glossy.

Maybe that works on casting too?

You do have to watch it with epoxies and there are lots of different kinds with different qualities. I had to try a lot of differnt types to get what I wanted, I am hoping that the ones I don't use can be used for casting. Mainly the problem with casting bobbins is the very complex 3D shape of the things, you have holes and cavities and thin parts everywhere...plus epoxy is not cheap and is very hard and brittle in general...and then there is shrinkage....hmmm. Ideally you would use a vacuum or pressure, I even tried a bit of this...but it is not an easy thing to accomplish and can be messy and dangerous...

Speaking of which...epoxy and solvents like acetone are harmful to breath and generally very inflamible. I ahve learn't one trick though, sometime you can stick the things in the freezer to crack them out of a temprary bobbin or mould. Remember epoxies are generally stronger than anything you are binding to and will stick just about anything. I use silicone spray on nylon like material but even pretty slick, it still sticks!!! Freezing it causes the metals and such to contract differntly from the other materials creating a bit of a fracture between them...just a little trick I thought up when nothing else would allow the things to be pulled apart!

Any thoughts on the small rare earth disc magnets that can be bought from Jaycar? I was thinking perhaps I could install one or two under each coil, and the circular shape of the magnets makes construction of retaining brackets much easier.

Rare earth magnets are intriguing things but generally not suitable. They are very small for an equivalent power, but the main drawback in most applications (unless you are working on very compact designs like my hex drivers) is that they have an extremely strong attraction to their own nearby opposite pole. It is hard to get the same "throw" as with a ceramic or alnico kind of magnet. In yours you may find that the field is not so drawn up through the core and the strings as it tends to be attracted back to itself....you could do a bit of a mock up with FEMM to see the effects. I think I worked out a 3mmx3mm disc to be equivielnt in power to an alnico strat pole 5mmx10mm but the shape of the field, while very powerful, is condensed into a very small area...you can go more powerful for more throw, but then you saturate the core pretty quickly (which may or may not be what you are after).

I say...get ye to a craft shop, have you got "Riot" art supplies or something down there in tassie, there are fridge magnets around that would be ideal...10mmx5mm ceramic discs, two per coil perhaps would be ideal. I even found some 20x5x5 edge magnetized pieces $2 for ten, that is what I used in my rail driver in my local asian bargian shop. Even the hardware might have some magnetic catches that could do the job...but there is no harm in trying.

I couldn't help myself and built a quick and dirty jig for making six alternatively wound disc coils 10mm round. I estimate perhaps 150 turns per coil, so it will need to be machine wound. My biggest concern is that epoxy will most likely seep between the coils, gluing themselves and the jig into a solid block...I will need to think a little more before I actually go ahead and do it, I may even have to wind a test coil without glue so that I can work quickly on counts rather than measurements. Clever little jig though, I used a drinking straw for the core and steel washers to separate the coils. I inserted cardboard to make the 3mm spaces between each washer which I will remove as each coil is successively wound. However, no use if it all sticks together.

I really shouldn't be spending a lot of time on such a departure from my main design but the idea of a surface mount mid driver and none of the switching hassles is pretty attractive, especially on my telecaster project. However, I should probably think about replacing the standard tele pickup with a strat type as I am not finding that little skinny thing to be much chop and with an HB in the bridge, it is likely to be grossly overpowered. Perhaps I should consider making it into a single pickup guitar and just make a dedicated driver for the neck position and be done with it, again no switching hassles, maybe do some kind of fancy active tone control to give a little variety to the thing...might turn out to be more useful anyway!

any thoughts?

pete

ps...good to hear you have been able to get so far with the sustainiac circuit design...I don't think I could ever get that far. It is probably this ineptness of mine that drives me to KISS. The bi-lateral and other driver ideas are equally valid with linear amp designs I suspect, if you want to put that much effort into the driver...but the single coil driver will work if anyone is still interested in this and is certainly a good place to start. For those who may not realize it, curtisa has already successfully made and uses the basic DIY sustainer design with some success...you do have to love the look of this thing though (still not sure it will work in a centre position between two HB's though, very serious doubts!)

[utopian isotope]

Mainly the problem with casting bobbins is the very complex 3D shape of the things, you have holes and cavities and thin parts everywhere...plus epoxy is not cheap and is very hard and brittle in general...and then there is shrinkage....hmmm. Ideally you would use a vacuum or pressure, I even tried a bit of this...but it is not an easy thing to accomplish and can be messy and dangerous...

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One possibility is to use polyester resin, but when cured, it can be too fragile, and needs fiberglass to support it. It also stinks awfully.

Too much hardener heats resin so much that it starts to smoke... just result of my ancient testings.

Even at present time, there doesn't seem to be available any liquid plastic, that allows easier molding. Or is there?

[psw]

Mainly the problem with casting bobbins is the very complex 3D shape of the things, you have holes and cavities and thin parts everywhere...plus epoxy is not cheap and is very hard and brittle in general...and then there is shrinkage....hmmm. Ideally you would use a vacuum or pressure, I even tried a bit of this...but it is not an easy thing to accomplish and can be messy and dangerous...

------------------

One possibility is to use polyester resin, but when cured, it can be too fragile, and needs fiberglass to support it. It also stinks awfully.

Too much hardener heats resin so much that it starts to smoke... just result of my ancient testings.

Even at present time, there doesn't seem to be available any liquid plastic, that allows easier molding. Or is there?

Maybe I didn't stress this enough...there things are dangerous...after smoking comes explosion and fire...I am not joking...

Polyester is always bad and you will never loose the smell! It is useless because of the shrinkage.

Seriously, a lot of my early driver bobbins were made of cardboard reinforced with glue. This is all the fibreboard that fender and like bobbin plates are made from, pressure heated...but you don't have to go that far.

One problem that should be obvious in making any kind of plastic molded part is that you need to have a part to take a mold from. So, you have to be able to make the perfect model, make a mold and make a successful cast from a mold...all very tricky and specialized skills. If you can do the first, for a one off, the rest is redundant.

Remember also, for this project, we are nowhere near having a design that could warrant the time effort or expense of making a cast part. Just about anything you may want to make can be made or adapted with some ingenuity. You can even make them without bobbins at all and save valuable space!

Newer participants should be aware that over the years, there have been theoretical trends in driver styles. For quite some time the rail driver was seen to be the way to go. For a little while before that, the side driver had some interest. The truth is that a really well made thin single coil will work, especially on a single pickup guitar without loops high powered amps or any other fancy strategies...it may take a few before you acquire the skills enough to get it right, but a couple of hundred turns of 0.2mm wire does not take long to wind...

The above early pics show two drivers, one from a cheap pickup bobbin about 5mm deep (unusually shallow) and the right one, a thin driver which was the prototype for the one that eventually fitted to the sustain-o-caster; an 8 ohm 3mm depth coil with thin cardboard bobbin (you can see I didn't even round the ends and they are folded under it)...hand wound with PVA potting...no epoxies at all.

Interesting, in this photo I was testing neodymium magnets below the 3mm steel core inside this one...they are the tiny little discs stuck to the bottom of it. The big ceramic magnet (of a similar "power") is on the other bobbin and worked a lot better.

This cardboard bobbin is alive and well today and was used for a lot of subsequent things including the "sustain box" and was also fitted piggyback style to my Les paul...

Making a "bobbin" is pretty tricky but there is no need if you are making something like a guitar pickup anyway. Look at curtisa's bobbin adaption. For a really strong bobbin plate material, circuit board stuff is thin and stiff and ideal really, just as you suggested, there are lots of plastics around us all the time that we throw out in the garbage, look around the kitchen, when out for a walk or in the supermarket or newsagent...the plastic I used for the sustain-o-caster's top plate came from a plastic folder that I bought for $2 just to get the two A4 plastic covers to play with...I still use this materail from time to time when I want a thin flat sheet of plastic. I am even considering using some again today to make the jig plates for my hex coil winding project.

Keep away from the chemicals...superglue is especially harmful if inhaled, I know I was effected by it and will not touch it except if nothing else would do and only as intended...steer clear of the stuff.

good luck... pete

[col]

Rare earth magnets are intriguing things but generally not suitable. They are very small for an equivalent power, but the main drawback in most applications (unless you are working on very compact designs like my hex drivers) is that they have an extremely strong attraction to their own nearby opposite pole. It is hard to get the same "throw" as with a ceramic or alnico kind of magnet. In yours you may find that the field is not so drawn up through the core and the strings as it tends to be attracted back to itself....you could do a bit of a mock up with FEMM to see the effects. I think I worked out a 3mmx3mm disc to be equivielnt in power to an alnico strat pole 5mmx10mm but the shape of the field, while very powerful, is condensed into a very small area...you can go more powerful for more throw, but then you saturate the core pretty quickly (which may or may not be what you are after).

Here's a comparison between a 6x7 mm basic alnico and a 4x1mm medium strength Neodymium.

You can see that there is very little difference (all other things are equal). The neodymium has a fractionally smaller field, but if you were to use a 6x6 alnico, then the alnico has a smaller field. The main thing is that both have similar 'throw' in the important area, and that the modulation of the field due to the coil is about the same.

It is possible that core saturation will play a part in the final quality of the result, but at least a driver should work with neoDs

cheers

Col

Edited March 15, 2008 by col

[psw]

Thanks col...yes they can work, and your drawing also nicely illustrates the differences in size. Size does matter in some applications as does 3 dimensions. First, let's say my "impressions" of comparisons are derived from actual experiments with the above coil for instance to which I could apply different magnets to it's steel core with all other elements (guitar, circuit pickups, etc) being the same.

If you look at the long side of the coil in a FEMM, you would see that magnetisim is drawn back through the core to the reverse of the neodymium in the gaps between multiple ones. Of course alnico and ceramic do much the same but, because the equivalent strength of alnico means that the magnet will be larger, then the gaps will be smaller or a magnet large enogh to avoid gaps could be used.

The other thing that came up recently in another interesting thread on pickups I was contributing to lately...overwound pickup myth?...was that it was suggested that ceramic magnets (not being conductive) did not add to inductance in the same way as alnico or I resume neodymium's do (as they are metal and are so are conductive).

Certainly they can work, the magnetic field is simply that, no matter the material used to create it. I was particularly enamored by neo's, have a lot of them and have endless fun playing with the things...my bias against them is in part due to the experiences mentioned and some peoples belief that being "rare earth" materials and extraordinarily powerful for their size, that they have some intrinsic, almost magical qualities. Also, most that are easily found are often overpriced and way over powerful. They too can be dangerous if anyone were fool enough to try and break or cut the things...you could be up for a posthumous "darwin award" if you do (tinker's should check out the movie or the real darwin awards if you don't know what these are).

But sure, why not. You can find neodymium magnets in disc drives apparently, G-mike used two for his driver in the tutorial, I postulated that these may have contributed to lack luster performance as two spaced magnets like this created a lot of gap to allow magnetism to flow back to their reverse poles through the steel of the core.

A specialized approach to using such magnets I am thinking of trying for my Hex idea...

The intention here is to use powerful neodymium magnets to provide a little more throw and to try and contain the field largely across the strings and through the cores like a series of horseshoe magnets...any thoughts on this strategy?

It would be difficult to make such a structure, at least as effectively without these little powerful magnets for instance, plus I have a bunch of them. They are not the kind of things you would want to point directly at the strings and even in this arrangement may be a little too strong. I was interested to see how these kinds of magnets were used in the fender/lawrence designed SCN pickups to manipulate the field between stacked coils.

pete

[col]

Thanks col...yes they can work, and your drawing also nicely illustrates the differences in size. Size does matter in some applications as does 3 dimensions. First, let's say my "impressions" of comparisons are derived from actual experiments with the above coil for instance to which I could apply different magnets to it's steel core with all other elements (guitar, circuit pickups, etc) being the same.

If you look at the long side of the coil in a FEMM, you would see that magnetisim is drawn back through the core to the reverse of the neodymium in the gaps between multiple ones. Of course alnico and ceramic do much the same but, because the equivalent strength of alnico means that the magnet will be larger, then the gaps will be smaller or a magnet large enogh to avoid gaps could be used.

the flux will always be drawn back to the opposite pole by the route of least resistance - doesn't matter what type of magnet.

Here's another femm plot this time side on (4mm deep)

On the left the core has two 4x2(x4) neoDs (with a big old 6mm space between them)

On the right, an identical core has a 16x12(x4) alnico.

The rare earth give a stronger field around the strings area,

Both show an uneven field with a dip in the centre.

If you were to expand this to a full length driver, I think you would get a similar result.

I'm sure your experiments comparing rare earths with ceramics/alnicos were valid. Why the rare earths didn't work so well is another question - could be lots of different reasons.

cheers

Col

[psw]

Hmmm...well something to consider...I kind of steer away from FEMM's lately, but I thought I'd do one up of the hex idea posted...

Can't make it pulsate hypnotically like yours though. Interestingly, although these are quite high powered neo-mags...you don't get the high intensity spots, but similar to the rails though, the throw is a little lackluster despite the power in these mags as you can see a lot of the more powerful magnetic intensity is between the poles. Perhaps magnetic poles would be better...hmmmm.

I was wondering if you have done a version of FEMM for the bilateral driver...how does that look as far as attraction betwenn the dual cores across the strings?

pete

[col]

Hmmm...well something to consider...I kind of steer away from FEMM's lately, but I thought I'd do one up of the hex idea posted...

Can't make it pulsate hypnotically like yours though. Interestingly, although these are quite high powered neo-mags...you don't get the high intensity spots, but similar to the rails though, the throw is a little lackluster despite the power in these mags as you can see a lot of the more powerful magnetic intensity is between the poles. Perhaps magnetic poles would be better...hmmmm.

Two things you need to consider.

#1 the colours in femm are meaningless unless you are comparing like with like. Either you must have the two models to be compared both in the same simulation (like in my recently posted comparison between neo-d and alnico), or you must edit the upper and lower bounds of the colour range by hand to be the same as they were for the simulation you are trying to compare with. By default, femm will normalize the range to try and match the average levels in the current model. With rare earths, this means that most of the pretty colours are concentrated in and close to the magnets. It's possible that the field strength where the strings would be, and the 'throw' of that plot you posted are better than anything else out there - can't tell without something to compare with.

To see what I mean, open up femm and produce a plot, then click the litle button on the toolbar with the diagonal coloured stripes on it. You should get a dialog that has two number fields at the bottom, one called lower bound and one called upper bound. Try changing the upper bound - half it and you should see some differences in your plot... sticking an extra zero just after the point will make a huge impact

If you want to compare two different results, cut and paste these two numbers from one plot into the other, only then can you truly compare the two by just looking at the colours.

#2 It _seems_ to me from my simulations that it is important to put the magnet(s) on the far side of the core from the strings - it looks like this allows the coil to have more of an effect on the field where we want it to. If you have the magnet between the coil and the strings, the field will be modulating nicely below the driver, and much less above it where we really want the most modulation. This probably isn't so much of a concern when using larger less intense magnets, but my guess is that little rare earths on top of the driver will dampen the effect of the coil rather than enhance it. I will need to do some more experiments on this to be sure.

EDIT: heres a plot showing the same driver, one with the neoD below and the other with is above. You can see that the one with the magnet above the core has a much stronger field where the strings are (much more than a normal alnico based driver). It also has less of that 'pumping' of the field where we would want it. The driver on the left with the magnet at the bottom is the one from my previous neo-d vs alnico comparison, it has a field strength in about the right range, and also has more movement in the field due to the coil. From this, it does *seem* that it is better to have the coil and core between the strings and the magnet.

I was wondering if you have done a version of FEMM for the bilateral driver...how does that look as far as attraction betwenn the dual cores across the strings?

I'm surprised you've forgotten the two plots I posted a couple of weeks ago

here is a link

cheers

Col

Edited March 16, 2008 by col

[psw]

Actually, things are moving so fast that I was too lazy to search them out...they do look good...

These were 7 pages back!!! BTW, we have had thousands of visits in the last few weeks and I know they are not all me...hi to all the lurkers, feel free to chime in with suggestions questions or encouragement...

my guess is that little rare earths on top of the driver will dampen the effect of the coil rather than enhance it. I will need to do some more experiments on this to be sure.

This seems to correspond with my experiments with them also...very much kills the effect. Similarly, you can't put the coil on the bottom of a pickup and expect it to have a great effect on the strings, it needs to be on top, the magnetism needs to pass through the coil...or so it seems.

I am still trying to think what I might do with my tele project, going through another heat wave down here so impossible to do anything much till it breaks... In fact, I have been playing tele's a bit lately, but the main project guitar is not a "typical tele". I have fitted the roller nut and khaler bridge and although I have a neck pickup, I am considering building a dedicated driver to slot in the neck position, perhaps even exploring something like an expander circuit for the tone control for added sustainer response...something like this guitar fetish SRV expander although these appear to be a remarketing of artec products...artec expander. Such a unit might compensate for the loss of the neck pickup (which on a tele isn't so hot and not suitable for the piggyback idea) and improve tone control and perhaps even bring out all kinds of harmonic effects, plus it is a preamp which wouldn't hurt either...

The hex idea was to perhaps see if I could fit something between the two pickups and surface mount it on a tele...could be ambitious even on this...so I might just wait on that, or see how curtis goes for inspiration. I do like my neck pickup sound, any ideas on how one might simulate this with a switch (an no the muffled tones of turning down the tone control is not going to cut it for me!

check you later... pete

[Bonfire]

I'm having some troubles with my little-gem amp. It works for a few seconds, but the IC overheats and the circuit stops working. It works again once cooled. What can be the problem? It seems that there's no short-circuit (I've checked several times) but I think the 10 ohm resistor is too low although I don't know much about it.

[psw]

I'm having some troubles with my little-gem amp. It works for a few seconds, but the IC overheats and the circuit stops working. It works again once cooled. What can be the problem? It seems that there's no short-circuit (I've checked several times) but I think the 10 ohm resistor is too low although I don't know much about it.

I am a little lost...there is a 10 ohm resistor in the "zobel" on the output connected to a capacitor to ground. Post the circuit you are using. Are you testing it with a small speaker...I hope so, what does it sound like? How do you know it is "working" even for a few seconds?

Yes, it should not get hot, maybe warm and you can blow it. It may be auto shutting down to protect itself if it is getting this hot. Generally, it could be a short on the output, if using a driver, you have measured the resistance? It might be an internal oscillation, something you would hear as squeal with a speaker.

Also...this is the Little gem...this is not the circuit people generally use with this though it might work...generally it is a fetzer-ruby...does the gem have a preamp transistor stage?

Anyway, as always more information required...

pete

[Bonfire]

I'm using that... but anyway, tomorrow I'm buying the components for F/R and forget the problems.

And yes, I'm trying it with a little 8 ohm speaker, and it sounds good. A bit distorted but good.

[psw]

Hmmm...well this is the most basic components just to get the LM386 to run. You are inviting oscillation with high gains if you don't put caps from pin seven and between pins 1 and 8 (say 10uF) and you may wish to play with the output cap (this says 220uF but I use 100uF to get a bit more high string reponse and harmonics). Also, A 1k trim pot for the gain between pins 1 and 8 with the cap is handy. You need the preamp part of the fetzer ruby to stop loading of the pickups, that is the main reason this "gem" circuit is not really much chop. A possible circuit is the ruby which has a preamp buffer, but the fetzer has a little more gain...the ruby may well do on it's own. Details of the circuits and layouts are on the DIY Layout software site...plus look in the projects as there is a good little tutorial on this project there also.

good luck...pete

[col]

I'm using that... but anyway, tomorrow I'm buying the components for F/R and forget the problems.

And yes, I'm trying it with a little 8 ohm speaker, and it sounds good. A bit distorted but good.

You have R1 in the wrong place!

R1 should be in series with C2, not between the LM386 output and the output cap C4

If there are mistakes this big in the build, then its anyones guess whats wrong

After you've fixed that and checked the resistance of your driver, it will be time to add a few extra caps, and maybe try swapping out a few components.

It is very important to double and triple check that the layout matches the circuit, and that the build matches the layout. (If you power it up with components in the wrong place, its easy to damage parts - not always enough to kill them, but enough so that they do funny things).

cheers

Col

[Andrew_Rivett]

I've been lurking for a while, and I was just wondering if it woud be somehow possible to build six seperate coils, each indepedently assigned to a seperate string. I think that would be pretty useful, being able to sustain some of the strings and not others. Anyway, let me know if you think it could work, I just might give it a try

[psw]

You have R1 in the wrong place!

R1 should be in series with C2, not between the LM386 output and the output cap C4

Well spotted col, even a circuit with these few components can come undone pretty easily by such an oversight. Now, I am sorry I didn't check the layout myself, I had assumed it cam from a reputable source...should be easy enough to fix...take out that jumper linking it to the output cap...

Welcome Andrew, always welcome more people and more ideas....

I've been lurking for a while, and I was just wondering if it woud be somehow possible to build six seperate coils, each indepedently assigned to a seperate string. I think that would be pretty useful, being able to sustain some of the strings and not others. Anyway, let me know if you think it could work, I just might give it a try

I did a lot of stuff on HEX drivers (six) and even proposing doing the same again as recent drawings show. However, it is not really possible, everything gets linked by the flux of the magnets so very hard to get them to work independently. Also, you would most likely have to drive it with a piezo bridge or synth like hex pickup. Then there is six times the circuitry, and what about all those selection switches...the ebow patent has an interesting idea for this, but it is doubtful that it would work. They illustrate a kind of keyboard behind the bridge.

Maybe someone should build a gizmotron...now that was big in my day...not!!! This had six rotating circular picks!!!

However, all is not lost...all these sustainers, even the single coil models are polyphonic. All strings will sustain, some more prominently than some, usually the lower strings although not always, my g and b strings tend to sustain pretty strongly.

What you need to do is develop a sophisticated damping technique just as you would if you were playing with very loud amps...an art in itself. EVH seems to be a master of this (when he's straight). Basically you can dampen the lower strings with the heel of the hand and the higher strings with the upper fingers and any others with the left hand.

In this way you can get pretty good control of the effect. I don't think selected string sustain will ever be available with this technology, if this is what you want or need, you are really looking at guitar synthesis.

However, you really are welcome to have a go and I am sure you will get a lot of support on this thread....

pete

[Chip]

Hey just thought i'd check up on any news on your sustainers psw, got any idea when you'll have a final product?. cheers.

[psw]

Hey just thought i'd check up on any news on your sustainers psw, got any idea when you'll have a final product?. cheers.

Welcome back again chip...sorry no news as yet. Life events, mostly not good, has held up the project. Mainly on the technical side is the problem of the switching. The "product" works very well, but in order to install it, there is quite a complicated rewire (which is common with all sustainer installations) but most importantly, a fairly big "twack" when switching off that is unacceptable. The likely solution is to design some kind of delay in an electronic switching so that there is a tiny gap between reengaging the neck and possibly middle pickup back into the guitar on switch off...so a bit tricky and I lack the concentration and motivation at this time to takle it...not to mention the expertise or a workable solution to try, so I am letting it lie for now till a solution comes. I know a lot of people are keen, but there is a big difference between a product and all the production issues and a DIY sustainer, for one thing a massive investment in money and time, so you would need to know that it is right.

The other thing, at this time the design only works on strat type guitars. with single coil neck pickups. Not a lot or evnough testing has been done on S/S/S strats to be sure that even this would work (the test guitar has a neck HB) so even a solution would need to be better tested out I suspect and a lot of problems may still exist. I really had hoped to be much further along by now as the circuit and driver design has proved to be very successful and great obstacles have had to be overcome to get it this far.

One disappointing aspect of this is that I have put my own main guitar out of action with extensive modifications and not got around to finishing it, not all sustainer related, but that is a part of it. Lately I have been thinking of simply wiring it back up in a fairly standard format and undoing a lot of work on it just to play the thing again!

I am also working on a tele and did a lot of fiddling about on it last night, it is finally coming along, it is a bit different from other tele's out there with an unusual bridge pickup and mounting and a kahler trem. I hoped to put a sustainer on this too but the design, even modified to fit, failed on a tele neck pickup. On a tele the neck pickup seems to be rarely used so maybe one could simply replace the neck pickup with a driver and have a single pickup guitar and avoid switching problems. I am considering this but that would be a departure in design. Now I am considering a thin surface mount device that may fit between the neck and the neck pickup. This may have some benefits that could flow to a strat or other guitar design but I suspect the switching problems will still be there if I do...but if I do this, perhaps that would be sufficient motivation, it will be a very nice guitar when finished.

Looking at that circuit again briefly...

I see even more problems with it...they have put a 25k pot on the output!!!!

Here is the circuit used from the DIY Layout creator (though marked "unverified")...

There are modifications I would make to this also however. For instance I would add a 10uF capacitor between pin 8 and VR3, on my circuits the output cap C5 may need to be varied, I have fairly consistently use a 100uF in it's place. VR2 is the volume control, you might want to build this off board to control sensitivity or something with a normal pot.

Perhaps one of us should make up a better layout for the F/R or better yet, a better basic "standard" circuit. One thing I have never liked about the fetzer ruby is the need to bias Q1, especially for new comers to circuit building. The fetzer preamp has very small gain, and perhaps a stock ruby is more the go here as it is just that little bit simpler. Basically these are variations of the data sheet circuit of the chip but I would add all the components suggested there for high gain operation.

Better yet would be for someone to devise a better solution and layout especially for this project, I have never built the fetzer/ruby so I can't really advise first hand. I had contemplated making circuits to sell just so people could get a head start on the project, they could end up cheaper than the components in the DIY...in fact that is the "origin" of my "product"...I figured I should probably make the coil too! While I could do that now, I couldn't in good conscience knowing that there are still problems with the switching side of things to be overcome. Once you buy such components as the coil, you are no longer really doing a DIY project but an installation and a "customer" has a right to expect it to work IMHO! In particular, work in a typical multi pickup guitar...so back to the switching issues again. I am still very keen on the commercial project and getting this technology out to more players as it really is a cool fun thing to play, but alas, not yet. So...waiting for inspiration or someone to suggest a "solution".

None of my issues should hold people back from making their own DIY versions...as you can see there are a lot playing with different ideas at the moment and the thread itself seems highly subscribed so anything you work on if posted is going to get a lot of interest and support.

pete

[Captainstrat]

Is anyone familiar with the Artec tone expander? http://www.artecsound.com/exp.html

What sounded fine a while back is lacking oompf after putting the home made sustainer down for a few months...the circuit needs more gain than what I currently have, and I wonder if one of the above expanders might accomplish that?

Edited March 18, 2008 by Captainstrat

[Fresh Fizz]

Mainly on the technical side is the problem of the switching.

Have you ever tried bridging the sustainer current on/off switch with a diode in opposite direction of the current flow? This should help against induction voltages.

I'm still working on a new sustainer driver. My complaint with the current one I have is what I believe Pete calls a lack of throw. High up the fretboard it's sustaining beautifully. My sustainer seems to be capable to do what I haven't heard in the clips of you, a Jimi Hendrix or Adrian Belew-like reversed volume swell. I need to play more staccato because the strings are swinging so fiercely while sustaining. But low down the fretboard is a different story. It seems that the strings are a bit out of the magnetic field - I have a dual blade driver in single coil format - and the sustain is weaker (on all 6 strings).

My new driver won't improve the throw. At least that's what I think. I hope that it will reduce the amount of fizz I'm experiencing.

By the way I found out that I could generate the fizz phenomenon by slightly moving a rod magnet à la strat above my bridge pickup. (Closer to pup, away from pup, sustainer not active)

This would mean that the change of magnetic field is responsable for the fizz. What I mean is that while moving the magnet with a frequency of 1 or 2 Hz I hear harmonics of the string in the kiloHz range. This means it is not enough to prevent the sustainer amp + driver to distort, the output level needs to be as low as possible to avoid the fizz phenomenon.

Cheers

Fresh Fizz