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About Donovan

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    Established Member
  • Birthday 10/19/1976

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  • Location
    New Hampshire, USA
  • Interests
    Classic Rock, Contemporary Rock, Blues, My family
  1. Col- What this thread DOES need is organization. Why not have one post that you repeatedly edit with the most up to date, clostest thing to success that each of you have. When you make progress, simply come back and edit it. Make it all inclusive, so that all you have to do is point us less technically adept folks to it and let us sink or swim. IMO, PSW should have done that at post #1, but why not start now and help cut down on the chapters of needless reading you mentioned? If it's well-written and coherent and speaks to the intended audience (those of us without a PHD in quantum mechanics), it would be very well received. Write it and they will come.
  2. Actually, can't count me in that list... I consider my project a failure on hold at the moment. I burned myself out from messing with that circuit and probably won't try another sustainer circuit until I learn A LOT more than I know now. I've been reading this thread on a regular basis, hoping to get up to speed, but Col and Hank are getting into some unchartered waters. With any luck, they'll have it sorted before I break down and buy a Fernandes or Sustainiac system.
  3. I've been in electronics manufacture for the last 10+ years and currently function as electornic assembly technical expert and trainer. Flooding and wicking might get the job done, but I would advise against it and use the paste and hot air technique or look into getting a tip designed for drag soldering (it holds liquid solder in a reservoir that dispenses a small amount of solder upon contact to each pin) as every time you heat the component and the solder joint, reliability of both component and PCB are reduced. One, because you increase the thickness of the intermatallic layer (junction of the solder joint and the PCB land) which means embrittlement that leads to fracturing and two because you're applying another round of extreme heat. Once you start using some of these more elaborate devices, you guys should also start considering an ESD-safe workstation to minimize the chance of rendering your devices nonfunctional due to electrostatic discharge. The basic setup would consist of a dissipative mat with a path to ground which is also common to any tools being used and the individual via a bracelt and ground strap. In general, the device datasheets should indicate an ESD sensitivity level. If it references ANY level, you should take heed in order to not waste your devices. The industry spends a lot of money on protection from electrostatic discharge prevention and this increases avery year as devices get smaller and more complex (weaker with regard to static shock). Nothing worse than trying to troubleshoot something that comes down to internal device failure due to an ESD. Checkout www.esda.org and give S20.20 a read if interested. I can also recommend very cheap ways of setting up the workstation for this.
  4. Hello gentlemen. I've recently been doing some reading about pulse width modulation using 555 timers as a means of more efficiently controlling electrical motors. The duty cycle is modulated, rather than pushing 100% of the time, it pulses power in the form of a square wave at a (for the most part) undetectable frequency. Just a shot in the dark, but could the analogy of the cruise control be realized as an AGC through the application of PWM to the output stage's power supply (or somewhere else in the signal chain) through a low frequency, say under 20Hz, with the signal amplitude modulating the duty cycle? That's pretty much the path I'm taking by using a PIC in my sustainer circuit. The PIC 'monitors' the sustainer's preamp output level & ultimately adjusts the duty cycle of its own PWM output stream to suit - if you feed this PWM stream into a low pass filter, you end up with a DC level - this DC level is applied to a 'gain control' JFET in the preamp (which adjusts the gain applied to the incoming signal to ensure a constant predefined output into the power amp) Thank you for that excellent explanation. I feel like I just learned something important and I'm glad that what I suggested had some merit, even if it's not an original idea! That is brilliant, the running it through a low pass filter portion. Am I correct in assuing this gives a nice smoothing effect, so the AGC doesn't act as choppy? Is this post-filtering a common technique and if so, what is it called or what other applications might I find it mentioned?
  5. Hello gentlemen. I've recently been doing some reading about pulse width modulation using 555 timers as a means of more efficiently controlling electrical motors. The duty cycle is modulated, rather than pushing 100% of the time, it pulses power in the form of a square wave at a (for the most part) undetectable frequency. Just a shot in the dark, but could the analogy of the cruise control be realized as an AGC through the application of PWM to the output stage's power supply (or somewhere else in the signal chain) through a low frequency, say under 20Hz, with the signal amplitude modulating the duty cycle? Forgive me if this is a daft idea for reasons beyond my knowledge level... just came to me when I read that quote. If the power amp stage would be too difficult, the signal could be sent to ground using PWM, but again, modulated, not a 100% shot at some threshold as has been recently discussed and tossed out. I do realize this is something like the "shunting to ground" that has been talked about already on this page, but was just thinking this would be a more translucent effect, in theory, or at least intuitively within the confines of my flawed psychi.
  6. Please don't be discouraged. I appreciate what you're doing. Though it's slightly over my head I read regularly and enthusiastically. I look forward to reading more of your results with this new circuit and seeing a preliminary dwg when you're ready. I've been keeping quiet here (as I am sure many others are as well) as I "learn" some more basics and tinker.
  7. Nice job! The front is very cool.
  8. Does alnico have a similar appearance/feel as ceramic magnets or is it noticeably more metal-like? Perhaps. If only we could see this stuff! Not sure I understand what you mean. I don't see the fizz as at all related to the signal being used to drive the coil. Should I? I have been able to drive the thicker strings quite hard, but the B and E strings are not effective above about the 14th/15th fret. Also, I have never gotten a consistent fundamental mode or harmonic mode. I have been able to use 2nd order all-pass filters to shift the regions and harmonic around, but there is always a mix in some places, harmonics in some places, and fundamental in others, never just one solid mode everywhere. This is 100% consistent across multiple drivers, multiple circuits with different preamp and amp configurations and different host guitars. Always, I am accompanied by a good deal of fizz. When I dial the amp circuit back to where fizz is gone, sustain loss abruptly follows. The problem has been consistency and strength on the B and high E strings above the 14th/15th fret. I have completely removed the middle pickups with no change in results vs. leaving the pickup installed and connected. Quite the opposite actually, I was able to get the same results using the middle pickup for the signal as the bridge pickup. I was originally using a test box with about a 2-3 foot in/out cable. All of my electronics were contained within a black box and I was building modular preamps, filters, and amp circuits as to easily connect/disconnect for testing. The results with this box were the same and when I brought my less than ideal results here, it was suggested then to ditch the box and do a direct install, biting the proverbial bullet. Again, the results are the same. I have fiddles with preamp gain, no preamp gain, 20X 386 gain to 200X 386 gain, driver distance to strings, signal pickup pole distance to strings, low pass filtering anything above 2kHz, all pass filters, half wave rectification, injecting all sorts of digital effects into the signal chain, all to no avail. I am at a standstill at the moment and have even considered biting the bullet and buying a sustainiac or fernandes system, if for nothing else to dissect the thing and make it all public (at least this should be simple enough for the driver portion) once and for all. You have consistently pointed to my driver being the issue over and over and I am convinced it is the biggest part of my problem. Hopefully, it'll get sorted. So, until I can build another driver... You guys are brilliant. Keep it up. I am still hopeful.
  9. Here I go again being intuitive. Let's call this extra length of magnet that hangs down "extra" for the moment. This extra length, is it being used? Is it not sending more magnetic flux laterally outward than shorter magnets of equal strength? You have gotten handy with some software that models fields, correct? Is this something you could model easily enough? Regardless, it sounds as though I am completely off base, but do you see where I am coming from at least? I mis-worded that. I want to not have the field so lopsided as it seems it would be in the configuration I have. Instead of equal magnet, I should have said equal field, as I would not expect that having much if any actual magnetic material above the coil is of use as it will put too much constant pul on the strings and at some point hinder any vibration. Isn't the entire field a sum of two components, a permanent field plus a temporary field's shift in one direction or another? So, whereas the overall summed effect is that the permanent field is weakened or made stronger, isn't this due to the continual destruction/reconstruction of the temporary portion in opposite polarities? Are you certain that fizz is due to the the strings acting as flux conduit? Brings me back to my original question about the extra magnetic material... I guess I feel fizz could be coming from the permanent magnets hanging down and emanating flux laterally. I never got fizz in the tests that I did holding the driver above the strings, upside-down. It only began occuring once the driver was actually installed to the pickguard. I then thought that some of it was due to shielding on the pickguard itself as Sustainiac removes the pickguard shielding, but then I installed the driver on my guinea pig strat, which is not shielded except for a tiny section, and the fizz is still as evident. More of the intuitive. I have tried only pulling, figuring the temporary portion of the field would react quicker and it would be a power savings as well. However, testing I did was completely unsuccessful. If I had to guess why, I'd say the coil could be likened to a speaker, in that it can not reproduce detail perfectly and so rounds any sharp changes, much like a speaker rounds the corners of a perfect square wave. I have no reason other than I guess I've grown discouraged and have been waiting for some materials to try something drastically different, but now that you've suggested it, I may. Thanks for the discussion.
  10. I didn't understand that, can you try and explain again ? I've been using SC strat bobbins. Not the cheapo type with metal poles and a bar magnet (though I have a few of those as well), but rather 100% magnetic pole pieces. My construction has been: unwind stock PU, bock up all but upper 3mm, wind coil in upper 3mm. This leaves the lower remainder of bobbin empty except for the lower portions of the pole pieces (total height minus the 3mm coil). I've not measured it, but I'd guess it's around 7mm to 10mm. What is the effect of having these poles left in their entirety as opposed to having polepieces only within the 3mm bounds of the coil? I know this is a theoretical best guess type of question at this point, but intuitively, I would think there is some waste with the extra length or an increase in fizz or some other EMI-related philoso-babble. I add this as question number 379 under "sustainer questions that shall never be (other than empirically) answered". Intuitively, I would think the system would like it better to have an equally-sized permanant magnetic field both aboe and below the coil. I would also think that as is, there would be more phase lag or shift on one half of the AC wave form than the other as there must be some sort of effect on destroying and rebuilding the field in the opposite polarity.
  11. Just checking in. I've stopped work on this project as I need a GOOD driver and I don't think my attempts have been there as of yet. I've used up my stock of spare pickups. No data, but something tells me that the extra pole magnet that sticks out from the used up 3mmm of the bobbing adversely effects the sustainer... any ideas? I have read here numerous times about not attempting to cut down neodymium mags, but what about ceramics? Can one safely file thsese down? I feel I need to make a bobbin from scratch, which IMO is a larger undertaking. I want to try and take advantage of multiple designs by making a dual coil thin design. I have my pals at work keeping their eyes out for scrap material for me to play with and until then, it's playing with circuits for now. Recently built and installed a 9v LED clipper fuzz on my guinea pig strat... not a permanent mod, more of an exercise in learning how to work with op amps more efficiently. Anyway, some cool posts as of late. Can't wait to see what comes of the things being discussed recently... Col's current mode 386 and hank's hex work. Keep it up gents... and pete, should you need an extra few bucks, would love to purchase a coil from you.
  12. I've considered them, but I want to use a battery for this project. The extra op-amp and two resistors that are needed to setup a virtual ground, and the very few extra components elsewhere are a bargain to pay for being able to use a single 9v battery IMO. The LM324 in the upper left of your schematic (this one) is the virtual ground, correct? It looks like you referenced the input signal to this after the 220nF cap, right? It is OK to reference as many other op amp inputs as you want to this as well? I thought they would interfere with one another somehow and so what I've been doing is referencing each op amp to half supply using the two resistors and two caps where you've used the one to send transients to ground. The results are LOTS of components, which is why I inquired about using two batteries. Space issues aside, if you were to use two 9V batteries instead of the op amp virtual ground, then theoretically, doesn't it become possible to remove not only the signal biasing, but the input and output capacitors as well, alleviating most of the circuit-induced phase issues? I'm a little hung up about understanding the difference between a virtual ground setup at 4.5V vs what I've read can be called a "true" AC when you tap the center of two seris-connect 4.5V supplies, whether they be batteries or whatever. I have trouble seeing the midpoint of two series-connected 9V batteries as being somehow different than tapping one 9V battery using a resistor network. The sources I believe are trying to say that the center point of 2 batteries is actually 0V, where intuitively I would see it as 9V. Can you comment/enlighten on any of this?
  13. Yes, I do like the versatility that uber-switching makes possible. I would like to learn more about them, any online site suggestions? I would like to read a simple site that goes into basic guitar wiring, especially switching and tone/volume controls. Uou seem to be the switch-king around here. The S-1 switch on my strat is intimidating to say the least and I would like to rewire everything neater than stock, but am at a complete loss... and yes, I've looked at the drawings on the fender.com site, but they are mfg drawings, not really a good schematic/dwg mix... sorry to get OT. Col- Have you played with dual power supplies at all to get rid of all the half power supply biasing and most of the capacitors that a single supply makes necessary?
  14. I'm still checking in regularly. I have concluded I need a better driver and so I picked up a bunch of tiny neodymium and ceramic magnets the other night to experient with. I have some steel flatstock to use for a blade and I am in-process with making a nice bobbin, but I am ditching the whole "use a pickup" idea for good. I did do some testing last week injecting lots of different effects, one by one, into the signal chain to feed the LM386 circuit and see if anything positive would happen. I fed reverb, delay, compression, chorus, phaser, flanger, tremolo, rotary, wah, auto-ya, and envelope filter in, but nothing at all got positive results. Chorus did give a pulsing effect to the strength of the sustain, but nothing useful really.
  15. Col- What do the little red X's mean on your schematic with regard to the power input/outputs on the opamps? I assume you are connecting power to them in those locations, or do you not have to?
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