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Location: Fairfax, VA | Decided to start this as a new topic. :)
Here's what I've found:
Most of the parts needed to assemble a Breadwinner/Deacon board are fairly easy to come by. The exceptions are going to be the inductor/power choke (it looks like a little donut covered with black rubber) and the switches.
First off, the inductor--the inductance of this thing is 1 henry. Not 1 microhenry, nor one millihenry, but 1.0 henries. Wow! Nothing even _close_ to that available from mouser or any other reasonable distributor. It looks like in order to reproduce the bw's inductor we have to roll our own. No biggie, just some added work. Inductors may be hard to come by, but cores, fortunately, are not. Easy enough to make a 1H inductor with readily available iron dust composite cores and copper wire, then seal them in rubber. Not cheap in terms of man-hours, but definitely possible.
The switches are another matter. There are multiple electrically identical switches available for the notch switch. Probably easy enough to find something that even looks and feels the same. I wish I could say the same for the pickup selector. There are electrically identical items, but I've yet to find anything that has a good sized toggle on it. I've dropped a line to the company that owns the company that bought the company that manufactured both switches in the first place to see if there are any stocks of them still available.
The rest of the components are all readily available. I'll let everyone know what I hear from the switch manufacturer, and try to work up some kind of pricing based on what the parts will cost plus some markup for the labor (I'd be etching, drilling, and populating the boards by hand, in addition to manufacturing the inductors).
Melmoth |
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Location: Fairfax, VA | Okay, a quick update after talking to the always helpful folks at Ovation.
Switches are the one part they still have fair availability on. They're not cheap, but they're also not ridiculously expensive (try shopping for 3PDT stompbox switches sometime). No luck at all on the inductors, so it looks like I'll have to get cores and manufacture any I want to use. That's hardly the end of the world, but it _is_ a pain in the butt (imagine winding small guage copper wire around a pig iron donut the size of a quarter--now imagine that you've got to do it an EXACT number of times).
Ovation is sending me an original schematic, so hopefully I'll be able to determine the specs of the one unmarked transformer and find something to replace it.
Once I know about these factors I'll be putting together a test board layout. Once I've got it done, I'll post the pcb design, bill of materials and maybe some instructions for people who've never made a pcb before along with pricing for making a board for interested parties.
If anyone has data on the specs of the single transformer on the board, I'd be very happy to get them. |
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Location: Upper Left USA | Melmoth,
It is about time we get to have an obsessive compulsive Electronics person on the board! Long overdue! The thirty year old circuit boards are the weak spot in keeping these instruments going.
Would it be possible to recreate in a solid state what the board does?
Keep it up! |
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Location: boulder | I'm with you all. It sounds ,uh,fun. No, I love to solder and build things. Finding time is usually the hardest part. Very cool idea and Nice effort Melmoth. Thanks, mike |
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Location: Fairfax, VA | MWoody,
Technically, the board is solid state with the exception of the pots, but I think I get what you're asking--could this be done in a smaller package with ICs or something. The answer is probably yes. You could, for instance, wire up a board using the opamp from a tube screamer instead of the FET preamp that the original used. You'd get a pretty good sound, too. The chip in question (usually a JRC4558D) is a dual op-amp which means you can do some interesting things with it--build in a switch to let the first stage overdrive the second, for instance or use both stages in parallel and provide a stereo output.
The sound, however, wouldn't be the same as the present electronics. I'm going to start by trying to produce a board as similar as possible to the original equipment and work out from there. The two things I'd most like to alter the board to allow are to add a rotary switch to replace the phase adjustment trimpot and allow on the fly adjustment between 4 or 6 levels of OOP including both pickups in phase with a bank of fixed resistors (although I think space for this is probably a bit limited--I might have to move the resistor bank onto a daughter board) and possibly to add similar adjustability to the notch filter.
If the parts aren't available it wouldn't be terribly hard to put together a circuit that would provide a similar FET boost using readily available parts. A preamp really isn't that complicated of a circuit. However, the BW/Deacon board is a bit more than just a preamp and some of the parts are pretty unique. Until we try to put together a new one we won't know how the modern components affect the sound.
As for being obsessive, I haven't done any of this stuff for about 20 years prior to deciding to buckle down and relearn all the project stuff I did as a kid. I've found it coming back faster than I expected, however, and have already managed to repair the switches on my Deacon, and am excited about the prospect of building new boards and mods.
Melmoth |
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Location: Upper Left USA | I can barely hang on to my Soldering Learner's Permit!
Good job! |
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Location: Fairfax, VA | Woo-hoo! I have found a replacement toroidal choke in the right inductance!
http://www.electronicsurplus.com/commerce/catalog/product.jsp?produ...
All I need now is the specs on the transformer and we are ready to roll! |
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Location: Orange County, California | Mel,
Just a quick question, and you'll understand the question 1 second after I ask it. What is the DC resistance of that 1H indutor? I have in the past used a cheap readily availble high wattage wire-wound resistor in place of a purpose built inductor. If you have access to a good LCR meter, you can likely find something else that will work. the next question would be "why is it there"? Is it necessary for the circuit to function? Could you accomplish the same thing another way besides adding inductance to that part of the circuit.
Pocket-protector & hat with propeller by day, worship musician by night.. Has a nice ring to it doesn't it? |
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Location: The Great Pacific Northwest | I missed this thread earlier... I have all of the parts for the original circuits, unless you are just looking to build new ones. email me.
mileskb @ aol.com |
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Posts: 76
Location: Fairfax, VA | Miles: Do you know the specifics of the transformer on the board? All of the other parts can be purchased either new or surplus and electrically identical. The transformer doesn't appear to be marked (at least there are no markings I can see without removing it from the pcb. |
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Location: Upper Left USA | Breadwinner Site
You've seen this site, haven't you? |
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Posts: 76
Location: Fairfax, VA | Yep. Was the site that first told me what it was I had bought at the pawn shop when I was in high school.
http://www.doremi.co.uk/breadwinner/diag3.jpg
That would appear to be the deacon/breadwinner preamp, but the details next to the transformer symbol are illegible. I'm hoping the schematic from Ovation will have more details. |
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| I believe Brudev has the schematics for these boards and the legends for components in his galleries.
GH |
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Location: Fairfax, VA | Again, yep. All of them except the transformer. It really isn't that weird when you look at audio transformers as a product. A lot of them were purpose made for specific applications. If we can't replace the transformer, maybe we can redesign the circuit to use a transformer with different specs. |
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Location: The Great Pacific Northwest | There are two methods for figuring this stuff out. One is to attempt to reverse engineer the circuit, the other is to dig out every similar transformer with similar physical attributes you can get your hands on and find one that works and sounds the best, or sounds like the original. Personally, I think the trial and error method works best and saves the most time in the long run. |
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Location: Fairfax, VA | Well, John from Ovation is sending me a schematic, so maybe there will be specs for the transformer on it. I'll let you all know.
Alls I know for sure is that I just got the battery plate cover I needed on eBay and told Miles to go ahead and invoice me for the pickups. Living, breathing, shouting deacon, here I come. :) |
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Posts: 76
Location: Fairfax, VA | Okay, a quick update on the function of some of the items in the circuit:
The question was asked: do we need that inductor?
Well, the inductor is actually the core of the notch filter. Here's a page with a schematic for a simple band reject (notch) filter:
http://www.tpub.com/content/neets/14181/css/14181_51.htm
I'd point out that there is an error in the second illustration as the white area to the left of the shaded area should say "Frequencies Passed" instead of "Frequencies Rejected".
If you look at Brudev's schematic, you can see that when the notch filter switch is engaged the inductor (L1) is wired into the circuit with the notch filter engaged. It and the capacitors are tuning the center and size of the suppressed frequency band.
The transformer is in kind of a funky place. I'm not sure yet, but I think it may be there to condition power to the transistors, which, with 18v DC and 1970's transistors, was probably a really good idea. |
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Location: Marlton, NJ | Mel - can you recommend a good reference book for learning more about the electronics involved in this?
Mike |
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Location: Chehalis, Washington | So, once completed, will you be marketing this by chance? Or are you keeping it all for yourself? ;) |
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Location: Fairfax, VA | If you're just wanting to learn electronics theory and overall practice, _Electronics for Dummies_ is actually a really good introduction. If you're more specifically interested in amplification and effects as they're used in guitars, there are a lot of places that I'd recommend you peruse to get your feet wet before dropping any money on a text:
If you're interested in how guitar effects circuits work, try this page:
http://www.harmony-central.com/Effects/effects-explained.html
The effects explained page did a lot for me in terms of demystifying what a particular type of effect did and how the circuit which creates it works.
http://www.smallbearelec.com/home.html
Small Bear Electronics is a great company and the guy who runs it is super-helpful. He also is one of the only sources I'm aware of for buying germanium transistors already specced and matched for building fuzz pedals.
http://www.geofex.com/fxtech.htm
Here's a PILE of good articles from the geofex site including R. G. Keen's absolutely essential "Technology of the Tube Screamer." I learned a ton about this stuff by reading these. |
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Location: Marlton, NJ | Thanks! I'm planning ahead for future projects - the first is restoring my Preacher to it's original condition - no mods. After that I'd like to fool around a bit more. I'm sure I'll be bugging you alot in the upcoming months :-) |
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Location: Fairfax, VA | Andrew - If (and keep in mind this is still an 'if') I can reproduce the original boards, I'll be making my pcb layout and bill of materials available free. It's not like I invented the thing, after all. That being said, if I can make a good replacement board, I'll certainly be open to building them for the solder impaired. |
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Location: Marlton, NJ | We should start up some Lunchtime Learning Sessions so the experts can impart their knowledge on the masses:
Mon: Transformers and Why We Love Them - Melmoth
Tue: 101 Uses for all that extra Veneer - MWoody
Wed: How not to bid on Ebay - CrimsonLake
12:00 in the large conference room.
Bring your own lunch. I'll bring the beer. |
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Location: Fairfax, VA | Actually, the thing I can't get out of my head since I started working this is the image of those electronics installed in a Telecaster with a set of Seymour Duncan humbucking tele pickups. I suspect it'd make for an absolutely evil country guitar. What would you call that? A breadcaster? Has a good full gospel open brethren kind of ring to it. :) |
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Location: Upper Left USA | Righteous! |
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Breadwinner/Deacon replacement boards...
