Primal Posted June 22, 2006 Report Share Posted June 22, 2006 Hey psw, I have a question. Have you tried making a driver without any magnets? My stepfather (who is a professional electrician) brought this point up to me: the driver is essentially an electromagnet generating its own magnetic field when it is running. Since the magnetic field generated by the driver is created via an AC current (DC wouldn't be able to vibrate the strings), he couldn't figure out why exactly a static magnetic field was neccessary. Any thoughts? EDIT: Question answered by reading previous posts. Link to comment Share on other sites More sharing options...
psw Posted June 22, 2006 Author Report Share Posted June 22, 2006 (edited) Yes Primal. glad you found your answers...it is a common misconception. Techniqually a pickup should work without magnets too (for the same reasons)..but not very well... The otherside of the coin is the thinking that you need strong magnets...more magnetic energy, more power. I was in part responsible by my use of Neodyminium (rare earth) magnets, particularly in my hex designs. These are powerful, true, but I used the tinyest 3x2mm discs. In the hex designs I created a powerful but complex "balanced field" by rigging twelve of these and the string vibrating within a neutral area between the north and south poles. The magnets were also not aimed at the strings. You don't want magnets that would inhibit the vibration of the metal strings or cause weird harmonics (so called "wolftones"). One of the beauty's of the pickup/driver concept is that it adds no additional magnets as it shares it with the existing pickup. If the driver is made separately, a magnet or set of magnets of a similar strength is all that is required. I have made a driver without a magnet...that one attached to the "sustain box" on the previous page has a core of mild 3mm steel. But it needs to sit on top of or held over the pickups magnetic field to work, or a magnet stuck onto its bottom. By making the driver like this (non-magnetic core) you can use your magnet for different driver prototypes and improved coils. I doubt that you will find a suitable magnet anyway...the only one I can think of is Tim's (onelastgoodbye) bobbinless, epoxy masterpeice with custom made ceramic magnet core...not at all an easy thing to do, usually the grinding of cutting of this material will break it, and demagnetize it...certainly it is not easy...the result was fabulous though, here's a pic again... Notice too the size of the device sitting on that humbucker...his core is wider than mine too...so you see the thing is not as big as a pickup coil at all...although it is a coil and magnets, it should really be considered a different beast to a pickup, with a different function. It is a lot easier to build than a pickup though, so don't be put off! love your work BTW tim... pete Edited June 22, 2006 by psw Link to comment Share on other sites More sharing options...
Primal Posted June 22, 2006 Report Share Posted June 22, 2006 Oh, don't worry, I'm not put off at building a driver at all. I've already wound one prototype, and I'm going to wind another today. Once I get all the bugs worked out and figure out what exactly I need (including which controls I will really need access to), I'm going to be gutting the neck pickup in my Epi LP and converting it to a sustainer. My goal is to be able to fit the coil and the circuitry within the housing for the humbucker in an attempt to create a self-contained system, with only the switchs, battery, and the specific controls I need separate (maybe even drilling the pickup cover and epoxying trim pots for gain and volume?). Hopefully once I get all the logistics worked out I will be able to add more to the discussion. My stepdad and I are also going to try to find a way to eliminate the pop on poweroff. Link to comment Share on other sites More sharing options...
psw Posted June 22, 2006 Author Report Share Posted June 22, 2006 Good idea...one I put forward a while back... It should fit and you really don't need the gain control really...I don't use it at all and wouldn't incorporate it again, fernandes doesn't either on their system...you can control it with your picking strength and damping technique. That would mean two switches. On a LP you could avoid drilling by making a master tone and volume for the bridge pickup and use the other two pot holes for the switches. You could use the selector to switch in caps for instant tone variation if you wanted...or put the sustainer's gain control there if you must have one! The use of a single pickup also makes the controls easier...you won't need to bypass the neck pickup...and, you could reverse the signal for the harmonic effect instead of the driver and avoid any driver cables through the guitar which can result in noise too if you are not careful. Sounds like a good plan, but take it a step at a time, make the thing go, then work out how to get it in there and the controls and such...good plan pete Link to comment Share on other sites More sharing options...
Primal Posted June 22, 2006 Report Share Posted June 22, 2006 I never use my tone control on my bridge pickup. I always have it cranked to treble, and sometimes there still too much bass. If I get this working, I would like to experiment with a simple wah circuit to test a theory I have about the harmonic mode. If you have ever played around with feedback using a wah, you know how you can get different harmonics to feedback depending on the position of the pedal. What I want to try to do is be able to pick and choose which frequencies come through in harmonic mode. I don't know if it will work, or if it will even be useful, but its worth a try. As for one step at a time, absolutely. I'll be breadboarding the circuit and working out all the kinks before gutting my LP neck pickup. One question, though. More than likely I'll be using the pickup bobbins that are currently in the pickup for my driver. Other than the lack of blade core, can you think of any problems? Of course, I will be blocking up the bottom to make a thin coil. My only concern is that the coil will have a wider core and won't work as well. Link to comment Share on other sites More sharing options...
blasteuteuf Posted June 23, 2006 Report Share Posted June 23, 2006 hi guys! i'm back. I tried to built a sustainer yesterday but it doesn't work......I used a wrapping wire ( totally resistor was about 6 ohms) and i put directly a magnetic core (magnetic bar from an old single coil pickup),is that the mistake? i built fetzer valve/ruby and i used my middle pickup as driver's input,my driver was in neck position and my bridge as my amp's input...when i turn the gain and volume knob from fetzer valve/ruby the driver makes noise even without amp after...so it reacts as a speaker..it makes biiiiiiip but no more sustain.....So now i make a new core in wood with steel plots (like a pickup) and i'll put a magnetic bar below the plots...but for the wire i've a copper varnished wire about the same diameter than the wrapping wire but i don't how th remove the varnish ( i used fire but it does'nt work so maybe a cutter? ).... I tought...maybe the mistake's coming from my capas cause i used only 10V capas. Another question: u need 2 pickups+1 driver or u can use 1pickup+1driver for this system and put in // the outputs like this: pickup output --->guitar's jack output \-->fetzer ruby input Thank's in advance for your answer.... Link to comment Share on other sites More sharing options...
Primal Posted June 23, 2006 Report Share Posted June 23, 2006 You can use sand paper, but I prefer to use a razor or scissor blades to scrape away the varnish. If you didn't scrape away the varnish on the magnet wire, you definately won't be able to get the sustainer to work. It would actually seem more complicated to wire the sustainer like you mentioned. Basically, just insert the sustainer circuit between your coil and your guitar's preamp. Link to comment Share on other sites More sharing options...
psw Posted June 24, 2006 Author Report Share Posted June 24, 2006 Hi there...good to see people trying this out... Ok...the sustainer takes it's signal from the bridge pickup and will only work with the bridge pickup to the amp. You connect the circuit permanently to the bridge pickup and to the guitars circuitry (via the bypass switch on multi pickup guitars or by selecting only the bridge pickup while testing). Wrapping wire wont suit. The "formula" for this is fairly specific even if it does allow for quite a bit of variation as you'd expect for a DIY project and for different applications. 0.2mm varnished wire as I have often described is important as is the thin coil design. There is a balance between resonant frequency and power carrying ability in this and variations have not been successful. Wrapping wire has quite a thick coating and is not suitable. A ceramic pickup magnet as the core is probably a little wide as it is (about 10mm). It is open to debate, but I feel that a thinner core (my blade core is 3mm) is a better choice. This "theory" is based on how a string vibrates, the higher strings and higher frequencies and harmonics have node points where on one side the string is physically moving up and the other down. I don't think I have adequately shown this idea before so here's a new diagram... If you consider the orange line as the string and the small arrows under the driver models as the force on it you will see that the force is down over the down side on the thin driver and the force on the wide driver is down on both the node and on the up swinging part of the string. This means the forces are at best cancelling each other out. With the thin driver it is less likely that it will sit on a node or inappropriate part of the string and it's force is more concentrated. If it were to be over an inappropriate wave cycle, it could also force through this a reversal of this cycle...this results in a gradual fade and re-establishment of the reverse cycle in some notes. These kinds of things are what greatly effect high string/frequency response; along with driver "speed", the coils resonant frequency, the placement of the driver, the driver relative to the source pickup, etc. It is worth noting that none of these considerations involve the circuit design, but that of the driver. Although I have suggested a very simple device, it's specifications are important for it to work effectively...variations will have different results. Typically, the low strings will be easily driven and I would be surprised if you couldn't achieve at least this on the first attempt. I wouldn't think that 10v caps are a problem if you are using a 9 volt battery BTW. You can check the circuit by attaching a speaker as if it were a practice amp...if it works, it works. The driver acting like a speaker is likely that the coil winding's themselves are trying to vibrate. Potting wrapping wire is impossible really, difficult to get a proper coil as it is because of the thicker coating, but that coating is teflon so that the wires esily slip and so will resist any attempts to glue them together. Also expensive, but does come in snazzy colors! As for using a wha circuit. I have found a wha to be very useful in harmonic mode for bringing these very high pitched sounds out. A wha circuit will boost certain frequencies that the amp will normally filter out as outside of the normal range of the instrument. So for high string harmonics to come out loud and clear, this is useful, but in general it should be very effective without the need for this. I have not tried the wha in the driver path, I am talking about it on the guitars signal just as a conventional wha would be used. It may be useful, it will have an effect, but what that effect will be, or how effective it is, I don't know. It could be detrimental and would at least make one without to start with. Using the bobbins should be ok...poles mean you will lack drive when bending strings, the thickness of the bobbin may also have an effect, and the coil being separated from the core by the inner part of the bobbin may also be a factor. Given that you will likely want to save space for your proposal, a blocked up bobbin will waste some of it. One of the attractions of course is that it looks like a "pickup" but a similar look could be made by making a thin plastic cover or even buying a plastic EMG style one to hide everything under (once you know it works) so that it doesn't matter how DIY your handicraft looks, and you don't need to destroy a pickup in the process. A humbucking pickup magnet should work but is possibly not the best (may need to be put on edge) but could be taken from the pickup and replaced if you wanted to use the pickup again at a later stage. I did make a driver from a bobbin that was about 5mm deep, not blocked up but with screw poles. It was not a normal bobbin type though and quite thin walled...you do loose drive between the poles...but is not a typical bobbin, so can't vouch for a more conventional bobbin type. I am not sure about the ideas about the thin core by the way, but these are my ideas on why it may be preferable and it gives me an opportunity to explain them a little better. One other thing that comes to mind is that a smaller driver (core) will present less EMI that will interact with other pickups. Anyway...all good stuff for conversation...keep trying pete Link to comment Share on other sites More sharing options...
Primal Posted June 24, 2006 Report Share Posted June 24, 2006 At the risk of asking questions and getting answers that have possibly already been answered in this behemoth of a thread, I have a few more questions. How do you wind your thin coils? There doesn't seem to be any easy way to mount it in a cordless drill chuck. Surely you don't do it by hand, do you? I've been throwing around a neodynium (sp?) based mounting system, but I haven't had a chance to try it out yet. Also, did you find steel stock the right thickness, or did you have to machine it down? Have you considered trying to magnetize the steel core itself to remove any need for separate magnets? It may be tiresome, but it would certainly be usefull when trying to reduce the package to the smallest possible size. Link to comment Share on other sites More sharing options...
psw Posted June 24, 2006 Author Report Share Posted June 24, 2006 How do you wind your thin coils? Ok...yes, I do wind them by hand and it is the easiest and fastest way...30 mins max! To give you the best idea, I have searched out all the pics I took when making my pickup/driver and have posted them on it's own thread in the electronics tutorial section...and here is the link:::::>Pickup Driver Pictorial Really, they are too small and the winds too few to warrant a machine. You will need to keep pushing in loose windings as you go. One good reason also is that the glue would simply spray out everywhere with a machine... The wire really isn't fragile like pickup wire so it wont break...making the bobbin probably takes longer! Also, did you find steel stock the right thickness, or did you have to machine it down? I found 3mm (1/8) steel stock (by about 12mm or 1/2 inch) easy to find at the hardware store. I cut it down to about 3mm then held it in pliers and ground it smooth on the top and rounded the ends. For the pickup/driver in the pictorial I got lucky...the pickup coil was slotted, even though it had steel poles. I got lucky again as the depth to the magnet to the top for the driver and the pickup coil worked out to be 12mm...the width of the steel stock...so I only had to cut it to length and round the corners to fit. Three times luck in that a replacement strat cover fit exactly once I removed the steel spacer the old poles screwed into that sat on top of the magnet and cut the top out of the cover. Here's the finished device... I will get aropund to annotating that link above in time, but the pics make it fairly clear...hope that helps... pete P.S. I am stressed out at the moment with legal matters so welcome the distraction Link to comment Share on other sites More sharing options...
Primal Posted June 24, 2006 Report Share Posted June 24, 2006 Ah, many thanks psw! I've actually been potting my drivers with wax, since I don't want to try to fool with wood glue as I'm winding (I'm notoriously messy with such things). I'll have to go back out and look for some of that steel stock. The hardware store near my house didn't have the 1/8" in stock. Right now I'm using 1/8"x1/2" steel stock, which actually doesn't work too badly, as it gives a good surface to mount the magnets on. I found a good source of magnets in these little toys that I found at the local dollar store (hard to explain, really), which yields about 20 small 6mm diameter magnets. I currently have 14 of them lined up on my core. I'm not sure about orientation, or even if orientation is necessary since they are just giving the coil and magnetic field to modulate (I believe that's the right term). The 14 magnets seem to give the core a magnetic strength that is slightly less than my humbuckers (using a super-scientific method of touching the tip of a screw driver to the pole pieces, then to my core, and comparing the two). If these prototype drivers work, I will probably stick with this design since its so convenient for mounting the magnets. If it doesn't, well, back to the drawing board! I think I'll be looking for some black pickup covers to mount the whole package in once I get to that point. It would be nice to salvage the neck pickup and not tear it apart. I've also got a bit of a theory that MIGHT explain why the higher strings aren't driven as easily as the lower strings. I'm wondering if extending the core further past the strings would help with the high strings. As I'm sure you know, the magnetic field on the edges of the pickup are actually weaker (or more precisely, more stretched out) than at a point in the middle of the pickup. By extending the core a bit more, it may be possible that the strengthened magnetic field would help the driver drive the higher strings better. Any thoughts? Link to comment Share on other sites More sharing options...
psw Posted June 24, 2006 Author Report Share Posted June 24, 2006 Right now I'm using 1/8"x1/2" steel stock That's the stuff!!!! (I'm notoriously messy with such things). oh...did I forget to mention it might get messy...that is why I used PVA...washes off with water...put some paper down to protect table...hahaha. Seriously, people have suggested other methods but superglue would have your fingers stuck together in no time and sets too fast, epoxy is tonic and difficult to work with...not sure about wax...needs to get right in there, coil can get a little warm in use too sometimes... The 14 magnets seem to give the core a magnetic strength that is slightly less than my humbuckers (using a super-scientific method of touching the tip of a screw driver to the pole pieces, then to my core, and comparing the two). Hey...that's the method I use.... just be aware that opposite poles attract and so it is very easy to get them mixed up on the core. if you stick one to the core it's opposite will want to stick to it. To be sure, test each magnet with another and mark like sides (the ones that repell) so you have them all the same way around!!! I found a good source of magnets in these little toys that I found at the local dollar store That's a good source of all sorts of stuff...down here it is a $2 dollar store though...money isn't worth as much you know in Oz!!! By extending the core a bit more, it may be possible that the strengthened magnetic field would help the driver drive the higher strings better. Mine extend a little (1/8") beyond the string spread on either side. I've also got a bit of a theory that MIGHT explain why the higher strings aren't driven as easily as the lower strings. There are a few reasons. The frequencies of the lower strings are slower so the driver does not have to change "states" as fast, there is more metal in them to work on, the waves are longer, to name a few. Interestingly, my lower notes morph into a sustained note an octave above that struck...could be the output cap on the circuit, the thin blade or just a quirk of this guitar. The device will work on bass BTW but mine has a precision pickup so would require two drivers of different polarities for each pair of strings, and a circuit to max out the bass...works though, interesting sound!!! Anyway...thanks for promting me to post those pics on the link above...that should make it clearer for everyone, and easier to find... pete Link to comment Share on other sites More sharing options...
Tony Enamel Posted July 2, 2006 Report Share Posted July 2, 2006 Hey all, Awesome thread!. I've been reading through it for a few days now, and I'm pretty sure I understand what I gotta do to make one of these things. A couple of qustions: I want a setup like PSW (driver on single coil, power, LED, harmonic switch and sensitivity control) What's the parts list? 1. steel core bobbin (I'll make one) 2. 0.2mm wire 3. glue and clamps and stuff to wind the driver 4. Fetzer-Ruby amp circuit 5. 2 switches (dpdt?) 6. LED 7. gain pot 8. battery 9. wire Am I missing anything? ALSO, where can I order a fetzer-ruby amp? I've seen schematics all over the net but I just want to buy one already put together and working. Thanks a bunch guys. Keep this thing going. Dezz Asante Link to comment Share on other sites More sharing options...
Primal Posted July 2, 2006 Report Share Posted July 2, 2006 Looks like a good parts list. You will have to build the Fetzer-Ruby amp, however. PSW was talking about putting kits together for people, but thats still in the works. As far as I know, unless you can pay someone on the forum, you will have to build the circuit yourself. EDIT: By the way, I am finalizing my sustainer system today. Just finished up the circuit and after lunch I'm going to put everything in place. I will post pictures soon, however I doubt I'll be able to get any sound clips. Link to comment Share on other sites More sharing options...
Tony Enamel Posted July 2, 2006 Report Share Posted July 2, 2006 Thanks for the response. As far as the amp goes, What do I need to build one? I've read in this thread, about the lm386. Can I just use one of those? I found this: http://www.national.com/pf/LM/LM386.html . If you scroll down a bit, you'll see several different models. Will any of these be suitable? Link to comment Share on other sites More sharing options...
h20rider Posted July 2, 2006 Report Share Posted July 2, 2006 Whew! A lot of replies!!! Link to comment Share on other sites More sharing options...
psw Posted July 2, 2006 Author Report Share Posted July 2, 2006 Hi Tony and welcome to the sustainer thread... Little busy now so be short and get back to you. The LM386 is made by a few companies and is a standard power amplifier chip. Those listed in your link are all different types of packages of the same thing...to solder by hand you will need a DIL package...the LM386 is very widely available from most electronics stores for $1-2. You can't use just the LM386 though as the pickups will be "loaded"...there will be an impedance mismatch, so you will need a preamp section...that is the fetzer part of the circuit (the single transistor stage). I actually use a different preamp section but the effect is similar...boost the signal and avoid loading (which robs tone and power). I don't think I will be making anything like this in the near future and am very busy at the moment so who knows. This is a DIY project you know! The harmonic switch is a DPDT but the on/off/bypass switch is tricky and I had to use a 4PDT switch to completely remove pickups and switch in the bridge pickup for sustainer operation. I posted a link to some pics of my current driver as it was being made...hope you check that out. You may find that you know someone that can do a little electronics...you may even find some generic kits of battery powered amps that would do the job...but I haven't found anything that really suits without som simple modifications. LM386 amps are not uncommon, but the preamps are trickier to locate. That is pretty much the parts list...plus a few wires!!! got to run... pete Link to comment Share on other sites More sharing options...
Tony Enamel Posted July 2, 2006 Report Share Posted July 2, 2006 Hey pete, Thanks for the quick response. I'm seeing a lot in this thread about making a driver (as, I belive, this is the critical part of the experiment) however, I would love it if someone out there with the electronics experience could give us neophytes a small tutorial on building the pre-amp/amp combo. Or, point out where I can find this info. I need to know what parts I need, where to find them, how they go together and how it connects to the guitar. I don't ask for much, eh? Thanks in advance, Dezz (my real name) Link to comment Share on other sites More sharing options...
Primal Posted July 2, 2006 Report Share Posted July 2, 2006 Okay, PSW, be prepared for more questions! I just finished my sustainer. I am having some major problems though (might have to do with my driver, however). First off, there is a lot of distortion in the signal when I turn on the sustainer. My stepdad has experimented with various things, but haven't been able to cure the problem. Also, when I turn the volume all of the way up, the sustainer seems to sqeal (microphonically) for the last few degrees of the pot's turn. It seems to be linked to the distance between the driver and the bridge pickup, however I have the driver in the place of the upper coil on the neck pickup (the coil with the adjustable pole pieces). Another problem I can't figure out. I wonder if it has anything to do with running the circuit on 12v rather than 9v, although it seems rather unlikely to me. I will have to run it past my step father. Oh yea, I also can't seem to get it to work in fundamental mode. It suffers from the same squeal problem as the upperend of the pot in harmonic mode, however it takes place over the last 45 or so degrees of the pot's turn. We can't seem to get the volume up to the point where it will actually vibrate the strings before the squeal sets it. The squeal also seems to be very sudden. Its not gradual at all -- one moment no squeal, the next moment eardrum piercing squeal. Any ideas? Thanks EDIT: I think I've figured out the distortion problem. DUH! I've got a 1k resistor going from pin 1 to pin 8 on the 386 chip. I'll do some tinkering tomorrow to figure out the optimum resistance there. Link to comment Share on other sites More sharing options...
psw Posted July 3, 2006 Author Report Share Posted July 3, 2006 Ok...monday night and I'm back from work... so, questions Dezz...I don't have a tutorial and I have confessed that my sustainer does not use the fetzer ruby circuit. This should be fine though and has worked for others. The circuit comes from Runoffgroove and they have a few articles. It is a combination of the ruby circuit below with the preamp section replaced with their fetzer valve circuit. My circuit is a combination of a generic LM386 amp circuit and a two transistor preamp circuit. These were adapted from kits with swaped components...but this did give me the circuit boards which makes it easier. There are a few examples of the fetzer/ruby circuit having been built here. It is a smaller circuit than mine potentially, but as it has no circuit board, makes it fiddly at best to make small. I had thought of building my actual circuit for people but I am not sure of the cost...if it got too high, it would make the project approach the commercial units....not good. Anyway...the LM386 is a complete poweramp in a chip and really requries little if any outside components to work...but there are some that will make it work better. Here is the circuit that I adapted for the LM386 part Now there are some changes to this...I have omitted the resistor completely between pins 1 and 8 but the 10uF cap is worthwhile addition to stop internal oscillation. I would try this Primal and leave out the resistor completely...this will give you maximum gain. The "zobel network" of the resistor and capacitor from the output to ground is also for this purpose and may help (10 ohm resistor and 0.1 cap). Now to your other problems Primal... I wonder if it has anything to do with running the circuit on 12v rather than 9v, although it seems rather unlikely to me. Actually it might be...if you are using a power supply, this can add noise into the circuit...but also it allows a lot of current to be drawn into the circuit. The circuit can take it, but it may be too much and sending the circuit into oscillation. Now...did you take my advice and test the driver over the strings before fitting it to the guitar? One reason to do this is that you are able to increase the distance from the bridge pickup by testing it over the neck. You may also feel if there is vibration from within the driver itself from loose windings not potted too well. You may also have vibration from your mounting method if the thing is suspended on springs and loose...it will try to vibrate itself! Your symptoms are typical of feedback interactions between the driver and the pickup. It is one of the reasons that I had too use a 4pdt switch to completely remove other pickups in the guitar's circuit. That said, my experiments on my Les Paul did work with just deselecting the neck pickup with the driver sitting on top...not pysically disconected from both hot and ground. The good news is that the amp is most likely working properly...test it with a speaker to check it. I would try it with a battery...this will limit the current draw. The power is supplyed by current, not voltage so even though it wont damage the circuit, it may supply too much power. By increasing power, you are increasing the amount of magnetic energy coming out of the device which will be picked up by the pickup. This ha the same effect as if you put a microphone directly in front of a speaker...squeel. If you have a neck pickup (do you?), you may find that the coil, even though one end is lifted may generate noise through the earth that is still connected. If there are loose wiring in the driver, these will vibrate and cause it's own high frequency noise. Lowering the current may be enough, maybe examine how well it is potted and if there is any internal vibration. So...what I would do for now, is to take out the driver perhaps and test it over the neck so that you increase the distance from the bridge pickup. Perhaps first try the battery thing, to see if that helps. If you are taking out the resistor (a good idea) replace it with a 10uF cap and no resistor between pins 1 and 8. Now, you did also mention another wha circuit...did you implement this. This could well cause this type of effect by increasing the treble. I put a tone control effectively to roll of the treble into the sustainer circuit but found that by disconnecting the other pickups the problem was cured and worked much better without it. You could also try rolling the guitar's tone down to filter out high frequencies as an experiment, to see if this tames the squeal and provides more clues. Hope that helps...let me know how you go... pete Link to comment Share on other sites More sharing options...
Primal Posted July 3, 2006 Report Share Posted July 3, 2006 Hi pete, thanks for the reply. I'll be sure to try the 10uF cap from pin 1-8. I am not using a power supply for my sustainer, I'm using a standard 8-AA battery clip (which fits quite nicely in my LP control cavity). Interestingly enough, over half of the current draw when idle is coming from the LED, haha. When actually sustaining, the max current draw I've measured was 130ish mA. I don't think I'm putting too much current through the coil. It seems that with this particular chip, the higher the resistance across pins 1 and 8, the higher the gain. It also makes sense that it works that way because, if you look at runoffgrooves page about the amp, you can use either a 1k, 2k, or 5k pot for the gain control, with the higher pots giving more overdrive. My plan is to get a 1k or so pot, set volume control to max, and adjust the gain to get the loudest possible clean volume as per runoffgrooves advice. I did use a test driver and a test circuit before I mounted it all in my guitar, and everything seemed to work alright, even directly over the neck pickup. My problems lead me to believe that it is something with the circuit. My stepfather noted that the circuit seems rather unstable -- one moment it will give me one result, the next time I try it, it gives a different result. I have a feeling that I need to reduce the gain control. I feel that that is where the distortion is coming from. The squeal is almost like the microphonic squeal you get when you turn on a ton of distortion and place the guitar an inch from the amp speakers. If the distortion is off, it wouldn't feedback that close to the speaker. Here is what I will do: 1. Adjust the gain for maximum clean volume to see if that takes care of the problem. 2. Place a 10uF cap from pins 1 to 8. 3. Try repotting the driver. 4. Look at other mods to the circuit. 5. Rewind the driver. Link to comment Share on other sites More sharing options...
Tony Enamel Posted July 3, 2006 Report Share Posted July 3, 2006 (edited) Hey pete, Thanks for all your help. I was wondering if you could sum up a parts list for the fetzer-ruby(caps, resistors etc. and thier values). I know almost nothing about electronics but, I'm determined to build one of these things. Trial and error is how I work best! Also, I've listened to the sound bytes from your sustainer. It seems to me that it works perfectly. Congrats on the success. Hopefully I can get similar results. Dezz Afterthought: I've studied the schematic and, from the looks of it, Here's what I need: Caps: 100u, 220u, 22u, 100n, 22n Resistors: 68k, 1M, 1k5, Variable resistors: 100k-B(vol), 1K-B(gain), 100K (trim) Other: LM386, Q1 Questions: 1. What is Q1? 2. Is this what I ask for at the store? 3. Have I missed anything? Thanks, Dezz Further Afterthought: Q1 is the amplifier. The schematic indicates 3 different choices (2N5457, J201, MPF102). Any preference? The Q1 component has 3 poles, ground, source and drain. Which one is which on the schematic? Edited July 3, 2006 by Tony Enamel Link to comment Share on other sites More sharing options...
psw Posted July 3, 2006 Author Report Share Posted July 3, 2006 hi guys... 5 am and winter fog so got to run to work again...but...It seems that with this particular chip, the higher the resistance across pins 1 and 8, the higher the gain. no...it is the lower value that increases the poweramp gain...so no resistor max gain x200. A cap will filter out some high frequencies within the circuit but still allow max gain. got to run, later... pete Link to comment Share on other sites More sharing options...
Primal Posted July 3, 2006 Report Share Posted July 3, 2006 I would beg to differ. My stepfather used to be a professional electrician. First we shorted pins 1 and 8, no resistor. Then we added resistance and got more gain... Link to comment Share on other sites More sharing options...
kowski Posted July 4, 2006 Report Share Posted July 4, 2006 I've studied the schematic and, from the looks of it, Here's what I need: Caps: 100u, 220u, 22u, 100n, 22n Make sure that the 22uF, 100uF, and 220uF caps you get are electrolytic. The schematic indicates 3 different choices (2N5457, J201, MPF102). Any preference? The Q1 component has 3 poles, ground, source and drain. Which one is which on the schematic? I picked up a 2N5457 transistor to use for my circuit, so we'll see how that turns out. Here is how the pins correspond: Also, here is some info from the LM386 datasheet about the gain: GAIN CONTROL To make the LM386 a more versatile amplifier, two pins (1 and 8) are provided for gain control. With pins 1 and 8 open the 1.35 kW resistor sets the gain at 20 (26 dB). If a capacitor is put from pin 1 to 8, bypassing the 1.35 kW resistor, the gain will go up to 200 (46 dB). If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor (or FET) from pin 1 to ground. Link to comment Share on other sites More sharing options...
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