fookgub

http://www.sears.com/sr/javasr/product.do?...p;bidsite=CRAFT Any used this or a similar tool? I was thinking it could make short work of sanding out arm and belly contours. I think you get locked into special sanding discs, but Sears sells 280 through 1000 grit discs for it and the prices aren't bad. Whaddya think?

1k is generally fine for 12V or 9V. If you want to get specific, the current across the diode is I = (Vcc - Vdiode)/R. You can look up the recomended current and voltage drop across the diode, plug it in, and solve for R.

Here you go. It's kinda hard to see with the flash and the coil and electrical tape both being red, but I did what I could. http://www.ece.utexas.edu/~wrobert/sus21.jpg http://www.ece.utexas.edu/~wrobert/sus22.jpg http://www.ece.utexas.edu/~wrobert/sus23.jpg

Ok, I'm back! Long story short, I got frustrated with my lack of usable results from this project and I set it aside for a couple months. I came back to it a couple weeks ago and started winding coils. After botching the first two, I promised myself I'd drop the project entirely if I didn't get the next one right. As luck would have it, the coil came out fine, and I now have what looks to be the final version of my driver up and running. It's non-microphonic, fits under my pickup cover, and is about the right impedance. Hopefully it will work fine, but I can't try it out until I finish the fretwork I was doing on the guitar. That'll be another week or so. Anyway, I have a new method for making these coils to share. My coil is like Pete's in that it's built on top of a working single coil pickup. The main difference is that the pickup cover is one piece, as opposed to Pete's design, where the top of the coil bobbin is also the top of the pickup cover. To get this to fit together right, I needed to have a "semi-bobbinless" (ie: no top) coil. After screwing this up a bunch of times, I figured out how to make it work. I make a temporary top bobbin out of two piece of cardboard (the thin kind found of the back of legal pads) laminated together with CA. I coat the underside of this with epoxy because titebond doesn't seem to stick to epoxy. Next, I rough out the slot for the blade with a utility knife, and finalize it with the appropriate sized drill bit in my press (sort of a very makeshift milling operation). Now I have a slot that's pretty close to the size of my blade polepiece and I'm ready to glue it on with gorilla glue (this is important... gorilla glue expands to fill gaps and it's very strong... perfect for this sort of thing). Also, I wax the bottom (epoxy side) of the bobbin prior to gluing for good measure. If the glue sticks to the bobbin, it will pull the whole coil apart when I pull the bobbin off later. After chipping the excess gorilla glue out of the winding area with a hobby knife, I'm ready to start winding. For potting, I've been using titebond "moulding" glue, which is just (I think) thick PVA. Regular white glue probably works as well, but now that I have a successful formula, I don't want to mess with it. First I tack one end of the wire in place on the bobbin with CA. I then wind the coil as per Pete's method, adding glue as necessary, and making sure to keep the coil tight. When I've got all the wire I want on, I tack the other end of the coil wire into place with CA (making sure to keep it tight), and leave the whole thing to dry for a couple days. I have not been wrapping my coils in electrical tape after winding, as this seems to inhibit the glue from drying. Once it's dry, I'm ready to peel the top bobbin off. This is the "make it/break it" procedure. First, I chip away all the excess gorilla glue, then I just peel the top off slowly, making sure that none of the coil comes with it. If all went well, I now have a nicely potted coil with no top, and I'm ready to put it together. Last time, I let it sit for another couple days after peeling the bobbin off, just to make sure the glue was thoroughly dried. Sorry I don't have any pictures of the winding process or the finished coil. I can get one of the coil if anyone wants to see, though. For now, here are a couple pictures of the whole thing installed in my pickguard. Notice the snap-in connector that lets me remove the pickguard without soldering. http://www.ece.utexas.edu/~wrobert/sus11.jpg And one of my "rapid prototyping board" with a Ruby Fetzer on it. I plan to build an eBow-style amp and a modified "Aussie compressor" as well. I'd like to evaluate all three before I commit a design to solder. I'd also like to check out some alternative harmonic modes, like half-wave rectification and the eBow-style thing (which I still haven't totally figured out). http://www.ece.utexas.edu/~wrobert/sus12.jpg Anyway, just wanted to let y'all know I'm still out there working on this thing

Guess it's a little late, and you're interested in humbuckers anyway, but... I've got a GFS P-90 in one of my guitars. It's a fine sounding pickup, especially through a bright (Fender) amp. I don't like it as much through my Line 6, but then I don't really like anything through that amp.

Looks good to me, too. the routing is clean and the shape looks right. I'm not sure I dig the contrast between the poplar top/back and the alder core... I would prefer solid poplar. But, the top is definitely wild... it would look awesome with just a clearcoat. One thing is bugging me, though. On the back, it looks like there may be a routing mistake on the moneky grip. Maybe it's just a weird angle, but I'd ask for a close up before I bought the body.

Thanks for the replies, everyone. I guess having no workshop isn't as good of an excuse as I thought, considering that even some GOTM winners were built on people's back porches. Anyway, now that I finally have a router table, jigsaw, and some other basic stuff, I'll be starting my first project after I move in August (a new RG style body for my Ibanez), workshop or not. So look out, GOTM 2010

Ok, I'm not sure if this belongs here, but I guess it's related to guitar building, so... I've noticed quite a few high-school and college age kids here. I won't list any names for fear of leaving someone out, but you guys know who you are, and the majority of you are churning out some extremely professional looking guitars. I'm fortunate enough to finally live in a house (after 4 years of apartments), but with no garage or shed, I don't have a good place to do any serious work. This also prevents me from having many of the larger tools you guys take for granted (table saws, bandsaws, spray booths, etc.). Until recently I couldn't afford those tools anyway, but the real reson I haven't built a guitar yet is that I simply have no place to work. So, I'm just wondering how you guys manage to do this stuff. Are your parents into woodworking, do you use your school's stuff, or have you already aquired your own shop and tools? Come on, spill it. Btw, please don't take this as accusatory... I'm simply curious. I have to admit, though, that I get a twinge of jealousy every time I see someone post a magnificent guitar and realize they're several years younger then me.

David, I'm not sure what to say here. On the one hand, it seems like an elegant way to mitigate at least some of the string balance issues. It would require a slightly different magnet structure than the current design, but I doubt that would pose much of a problem for you. On the other hand, I feel that the blade polepice may be more effective in directing magnetic flux toward the strings. I have no evidence to back this up, though... I guess you'll just have to experiment. (holds breath and waits for Pete to announce he's already tried it...)

As crafty says, you could use a mono jack with a separate switch, but it's not advisable. You can use a mono cable with the switched stereo jack that comes with the Graphtech system, though. With the mono cable, you have to blend the magnetics and piezos to one signal. Using a stereo cable allows you to send the magnetics and piezos to two separate amps. I have to disagree with crafty's assessment on blending (I often blend a touch of piezo in my clean signal), but that's really just a matter of opinion. Having two separate signal chains allows you much greater flexibility, and may actually be easier to deal with on stage. Either way, it's seamless with the Graphtech system. For stereo operation, plug in a stereo cable, for mono, use a mono cable... simple as that. Just follow the instructions that come with the preamp.

Yup. Use the jack that's included with the Graphtech system, though. The battery switching on the Ghost preamp is a little funny. IIRC, the preamp is on when you break the switch connection to ground.

You should be able to fit the 9V into the cavity, so I doubt any routing will be necessary. Make sure to buy the preamp and not just the saddles. It will come with a new jack and some instructions. For easy switching, I recommend the optional "quick switch," which lets you switch from magnetics to piezos to both. Without it, you're stuck with a two volume "blend" system, which works fine, but is probably too much hassle for stage use. With a mono cable plugged in, the piezos and magnetics will be blended into the output (dependent, of couse, on the "quick switch" setting). With a stereo cable, the piezo output is available on the ring terminal.

man, this month was tough. Scott's double cut was simply perfect. I loved the wenge topped LP and Godin's wenge guitar. The Mu X was also really neat. I'd love to own any of them, but in the end I had to give it to scott.... that thing is just out of this world. Great job to all!

No bottom ferrules on most models, either. Nope, he's actually built and sold quite a few basses, and has been doing it for years. He's got quite an... umm, interesting reputation over at talkbass.com if you're interested in reading up.

I see no problem with the circuit you've drawn. The Graphtech system's auxiliary power output should be the same as your power supply voltage. This is based on what I know of the Ghost system. It may be different when you have the midi converter involved, but I doubt it. The good news is that the 386 will run from a variety of power supply voltages. I wouldn't go much below 8V, but you can easily go up to 12V. Some 386 varieties will run up to 18V, but you need to check the datasheet to make sure you have the right part. Anyway, I can't wait to see the finished product... I'm sure it will be excellent.

David, the short answer is yes. The longer answer is that you'll need to think about how you're going to hook it up. Do you have a buffered output available, or are you going to connect the piezos in parallel with the midi converter? In the first case, you're pretty well set. In the second case, you need to increase the input impedance of the sustainer amp (I'm assuming you're planning to use the Ruby-Fetzer circuit here).

I see a couple problems with what you want to do. The biggest one is that the 550 has a better neck than the 170, so why replace it? A bigger upgrade would probably be to put a 550 neck on your 170.

Just a little bump here. I tried out the eBow circuit on my bench yesterday, and it works as drawn. Very interesting stuff. The output is a full scale square wave when the input exceeds a certain threshold. There is no output when the input is below the threshold, which gives the circuit very good rejection of noise and low level signals. The harmonics switch varies the duty cycle of the output square wave, but does not appear to invert the phase. For now, I've just been testing with my function generator. I'll know more when I get it hooked up to my guitar. My sustainer coil is getting better. With my modified Ruby-Fetzer, I've been able to get most of the strings to sustain. It takes some coaxing still, though. Sustaining is actually easier in harmonics mode because I can crank the gain higher before it starts to oscillate. I'll have to take a closer look at that. I've been having some problems with noise from the driver getting induced into my signal, too. I don't know if it's coming through the ground, the amplifier circuit, or if it's being induced directly into the bridge pickup from the driver. Anyway, it's progress for sure, so I'm happy about that. Eventually I'll wind another driver (hopefully my last one), but for now, I'm going to keep the one I've got and use it to test out a few different amp configurations. I ordered a few BS170's, so I'll be able to try out the compressor that lk suggested a few pages back. When all is said and done I'll have a least three amps to compare head to head : the Ruby-Fetzer, the eBow, and the 'Aussie Compressor'. I have a feeling the Ruby isn't going to come out on top here, so this is a chance for me to actually contribute something new to the project. I'm also starting to get some ideas together about how I'm going to rebuild the eBow. I'm not going to reuse anything from the original except the casing, meaning that the final result should be a project that anyone can build without having to raid an real eBow for parts (that would sort of defeat the purpose, no?). I won't give anything away yet, but it's going to be cool.

First, you should not use the iron to 'paint' the solder. Use it to heat the joint, not the solder. It sounds like your tip isn't tinned. Is it clean? You my have to use some flux to get it to stick.

Ok, just to prove I have been doing something lately, here's some more junk about the eBow. I'm not sure if I should be clogging up the sustainer thread with this stuff, so let me know if you guys want me to move it to a new thread. I traced the eBow's circuit last night and did some measurements on the coils. Let's start with the circuit. Here it is, copied directly from a real eBow. Notice anything funny? Yeah, positive feedback. I'll double check that when I get home tonight, but I'm almost positive (pun intended ) that it's right. So, how does this thing work anyway? Most of it is pretty standard, but I haven't figured out the normal and harmonic drive modes. Flipping the switch to harmonic mode raises the DC ground by .7V on everything except the driver. Apparently it works, but I don't know how. By the way, I wouldn't count 100% on the polarity of that diode being right in my schematic... I couldn't read the marking. I also don't understand what's going on with R2. Maybe someone else can shed some light. Anyway, here's a parts list. U1 - definitely an LM386 R1 - definitely 1k R2 - looked like blue/brown/orange/brown, which would be 61k, 1%. I'm not completely sure about this, though. C1 - couldn't read it. Looks like about 47nF C2 - couldn't read it. Looks like about 100uF C3 - couldn't read it. Looks like about 220uF C4 - couldn't read it. Looks like about 10uF D1 - probably a 1n914 LED1 - blue LED. T1 package. SW - center off mini SPDT slide switch I know one would expect to see 10uF for C2, and 100uF for C4, but that's not what I saw. FYI, here is another eBow schematic I found on the internet: http://www.ece.utexas.edu/~wrobert/sus_schm_v1.jpg This is a much more standard circuit with no harmonic mode. Probably from an earlier eBow version. The part values sort of agree with what I saw. I don't think the coil values are right, but I'll get to that later. Here is a layout I did. It's mostly the same as the real eBow, except I moved the LED onto the board for clarity and I left out the cutouts for the coils. The connector on the top left goes to the battery and switch. The middle connector is +9V, while the other two are the two sides of the switch. There is one funny thing about the layout. Notice those big pads at the bottom? Those are in the real layout, but I don't know why. They wouldn't make much of a capacitor, and I don't see any need for test points on the board. Someone put them there on purpose, though.... ideas? http://www.ece.utexas.edu/~wrobert/ebow_layout_all.jpg http://www.ece.utexas.edu/~wrobert/ebow_layout_top.jpg http://www.ece.utexas.edu/~wrobert/ebow_layout_bottom.jpg Ok, enough about the circuit. Let's get to the coils. Contrary to what I said earlier, the pickup and driver coils are different. The pickup coil is wound with 42 AWG wire, while the driver is wound with about 36 AWG (I'm not sure exactly... but it's somewhere around 35-38). Although I wasn't able to measure them directly, my (very rough) calculations put the driver at about 20-60 ohms and the pickup around 500 ohms. The coils are bobbinless, and they look like this: http://www.ece.utexas.edu/~wrobert/coil-diagram.jpg I should have wrote ferromagnetic instead of ferrite. The rings are not the same material as ferrite beads... they are probably steel. The poles are .15" in diameter, and the rings are .42" i.d. and .5" o.d. The poles, rings, and coil are all .18" tall. The magnets are .5" in diameter and .1" tall. Refer to my earlier eBow posting to see how it all fits together. This should be enough information for you to calculate your own estimate for the coil impedances. Please feel free to do so... it would be nice to have a second opinion on that. Anyway, I guess that's about it for eBow stuff right now. All of this needs to be double and triple checked, so I'll try to get to that later. Here are the Express files if anyone is interested: http://www.ece.utexas.edu/~wrobert/ebow-traced.sch http://www.ece.utexas.edu/~wrobert/ebow-traced.pcb In sustainer news, I wound a new coil on my combined pickup/driver and I've been letting the glue dry for the last couple days. I hope to try it out either tonight or tomorrow. I used titebond moulding glue, which is all I happened to have. It's like regular PVA except thicker and dries slower. I accidentally grabbed a spool of 30 AWG and didn't notice until I was halfway done winding it. I ended up only being able to get about 6 ohms on the bobbin. It's a little sloppy, too, so I'm going to have a tough time convincing myself not to redo it even if it does work. I'm really hoping it works though... it would be very nice to finally get a working prototype after all this effort. EDIT: Double checked the schematic and layout, and I think they're both right. I'm still not sure about the polarity of D1 and C4. I'm also not sure about the value of R2.

All this talk about switching got me thinking about that eBow circuit again. I still have no idea how they do it, but my preliminary search didn't come up with any CMOS switches with a low enough on resistance to be useful for the driver phase switching. Here's what I came up with using a latching DPDT relay: EDIT: Schematic removed because it doesn't work right. It was too complicated anyway.

Nope, it means CMOS. My only issue with electronic switching is that, while it eliminates exotic (expensive) mechanical switches, it doesn't cut down on wiring clutter. It's also one more thing to build. On the other hand, it could be pretty small and could provide optimal switching. :shrug:

Well, the guy said he had never noticed the volumes interacting. Apparently this is his first Paul. I assume he, like most people, just runs the volume wide open, in which case the two circuits become essentially identical. I ended up leaving the wiring. By the way, the pickups he had me drop in were a DiMarzio P.A.F. and a Super Distortion. Sounded pretty good... better than I thought they would. Very 'rock'. He's got a set of Evos that he wants me to drop into his Ibanez next. I've been wanting to check those pickups out, so I'm looking forward to it.

Thanks for the info. I'm going to leave it like it is and explain what I did. I can always switch it back in about 5 minutes if he doesn't like it.