RTurner

Every once in a while I'll forget to drill out a hole in a PCB. It happens. That's why you should get yourself a jewelers hand-drill. It's basically just a handle that fits small drill bits. But this way you can be reasonably sure that the only thing that will break is the drill bit. BTW, if you take this approach- be real careful with tungsten bits. they're brittle. It's often better to use steel bits for this reason.

For creating home-brew panels, you can use any graphics program that will let you set A)the size of the image, and B)the resolution. Other than that, it'd be nice if the program has a reliable way to calculate the position of what you're drawing. Vector based graphics programs are probably the best choice, but are only absolutely necessary when dealing with CAM work (and for that matter, a lot of shops have the ability to convert black and white raster images to vector). I would recommend some sort of cad software, since you'll be able to reliably place features and text where you want them. I believe that mathcad and turbocad both have trial versions. Autocad would obviously be the best choice- I'm not going to tell you to bittorrent it, but, it is out there, and I believe that there is a light version which will do everything you need (not to mention that they almost give ACAD away to students... Remember- they make their money off of architecture and engineering firms, not people doing the occasional panel layout). A program like Adobe Illustrator may have a shallower learning curve, but isn't (in my opinion) as functional as even the worst CAD program for something like this. A brief explaination: Vector graphics are graphics files that contain instructions for the computer on where and how to draw lines, arcs, etc..(which is why they scale better). Raster graphics are graphics files that contain (generally speaking) pixel by pixel information as to their color and luminescence. In summary: Vector graphics: draw line from point 2,4 to point 5,6 Raster graphics: pixel 1= 255 2=122 etc...

Ok, this isn't strictly midibox related since these will be going into a Neve 1081 clone, but I managed to find a local source for Grayhill Series 71 switches. for 75 cents apiece. And yes, they're the hollow shaft sort. Ok, enough gloating over my good fortune. Does anyone know anything about the Grayhill series 71 type CY (it appears to be identical to type CK, but I dunno)??? It's one pole 12 position, modular multi-deckable, hollow-shaft, pcb-mount.

I wouldn't worry too much about using PCB mount RCA jacks unless it's integral to your case design- otherwise (and this is usually way better in terms of headaches re: getting everything to fit together) use panel-mount RCAs with solder lugs/cups on the back- and wire it together using jumpers. I'm not intimately familiar with the PCB for the SID module, but if the pin spacings for the RCA jacks will accommodate some sort of screw terminal- I'd suggest doing so.. If mouser and digikey don't have parts that meet your requirements, I'd suggest trying a more specialized distributor like Parts Express or Antique Radio Supply- since they more towards the DIY audio crowd. Good luck, Robin

Just an idea: Instead of paying for engraving, if you've familiarized yourself with etching your own PCBs using the toner-transfer method- then you can do the same for your front panel. Of course, you'll want to protect all edges and large areas not to be etched with masking tape. Ferric Chloride or Hydrochloric acid + Hydrogen peroxide will attack Aluminum. If using some other metal- you can look up what acids will attack what, but my recollection is that either of the above will do most common metals. Don't get ripped off! Oh yeah- I don't believe this will work on anodized surfaces.

Hey, have you checked out the pads at www.sparkfun.com??? Some months back I put together an autodesk inventor file for the sparkfun monome-esque pads and posted it here somewhere...

DrBunsen- Sorry, I live in the states, in North Carolina. I have to pretty much order everything over the internet and/or phone. Coincidentally I live about 10 minutes away from the Moog Factory (somewhere off riverside drive....) But there are, as far as I can tell- and I am a recent transplant- no chemical suppliers, and no electronics suppliers (except for <cough> <gag> radio suck). George- Yeah, for real, stay outside with the stuff. Those fumes are acidic, and can damage whatever they come in contact with, including your lungs. So that you understand the seriousness of that- when people die of 'smoke inhalation' in fires, they actually die from the formation of HCl within their lungs (remember that wood is cellulose, which is long kinda multi-threaded strands of sugars, which are mostly hydrogen and carbon). at any rate, keep it outside. Robin

It always seems that the more sure I am about a board being completed (which leads me to sometimes epoxy-ing in shadily mounted components), the more likely I'll have to sit there with an exacto-knife carefully chipping away the epoxy from the leads of what is invariably the most expensive or hardest to find component on the board. Beeswax seems like it'd be a good idea, but what temperature does it melt at? 90% of the electronics I've been working on recently has been tube-based, and I doubt beeswax would cope with the high-voltage components. Maybe some kind of foam that could later be dissolved??? On the other hand, if you're securing just jumpers, you could always just desolder it from one side, and cut them out from the other... Seems like you could still salvage a board after that. Robin

Most aluminum sheeting that ends up not being sold as straight-up sheet metal will have an enamel coating on it, since aluminum is decently reactive. Also, if I remember correctly, aluminum used for casting has silicon added- which makes it easier to cast for one reason or another- but also makes it unsuitable for etching. My guess, without looking into it, is that you could possibly remove the enamel with some sort of non-polar solvent. Try using goof-off or one of the scarier non-polars that usually are used in industrial applications... Have you tried Comet BTW??? If you're looking for sheet metal, and you don't mind waiting for shipping- Mcmaster-carr (www.mcmaster.com) has all sorts of materials. Usually metal being sold as sheet metal (as opposed to flashing, which would be coated to protect it from the elements) doesn't have any treatment. Plus Mcmaster has some pretty cool stuff. Everything from 2" thick sheets of hard felt (the sort of stuff the beaters for bass-drum pedals and timpani mallets are made of), sheets of silicone, perforated brass sheeting (like the tops on a bunch of vintage hi-fi tube amplifiers), woven metal cloth (microphones), all manners of metal cylinders (custom-lathed knobs?). The list goes on and on. Lets you select materials by ASTM numbers. It's a very cool place, and has everything you need for fabrication that you can't get from digikey/mouser.

Therezin: When you etch aluminum with HCl, you have to use a negative mask. That is, you have to mask the areas you don't want etched. BTW, even though it'll darken the areas that get etched, this wipes off pretty easily... I believe that the dark stuff is AlCl- the main differences in appearance are A) (the most obvious) it's etched, and with a 5-10 minute dunk can etch as deep as an engraver would cut B) It dulls the area that's etched, making it look more like zinc. C) It pits the etched areas, which IMHO looks pretty cool. Unless you want to make the stuff boil over, make sure to mask the edges and the back of whatever you're etching. Also, this reaction, if my chemistry class from 10+ years ago still serves me right, releases hydrogen gas, so, as always, do this outdoors, and don't hold any lit cigarettes over the etch (though it honestly probably couldn't do more than singe your eyebrows). HCl will attack most metals, so you're not just limited to Aluminum. In fact, an ancient recipe for an etchant that will dissolve pretty much any metal is called Aqua Regia, and is a mixture of HCl and Nitric acids. Though Aluminum is the most dramatic, etching pretty much instantly. The etched parts don't have a whole lot of contrast from the regular panel, so you could do something like use a low-viscosity enamel paint to kind-of fill-in the etched areas. Good luck Robin

Muriatic acid is more widely called hydrochloric acid (HCl). It was named muriatic acid hundreds of years ago as a reference to brine (aka salt water) from which it can be made. Sulfuric acid (H2SO4) was originally used to make hydrochloric acid by adding salt to it. At any rate, HCl is as dangerous or safe as your handling of it. Under some extreme conditions it can form chlorine gas, and it can also form an acidic vapor if over-heated and/or over concentrated. These are the two reasons why it should never be used indoors. As far as direct contact on the skin, it's a strong acid and will burn you, but you'd have to be nerve-dead to get a bad burn- because it takes a matter of tens of minutes to actually do any damage, all the while the itching/burning sensation is slowly increasing. Treatment is: thorough washing with water. However, if the vapor is deeply inhaled, you need to see a doctor (and I don't mean getting a little whiff of the stuff, but inhaling a significant amount- enough to burn the lungs badly enough for you to bleed into them). Again, you have to use it outside. Also, if any liquid gets into your eyes, IMMEDIATELY flush with lots of water, then go to the hospital and pray that you haven't blinded yourself. Always wear goggles. I know that sounds intimidating, but, it's really not too bad if you follow some simple rules, most of which are common-sense: Always wear goggles. Always wear gloves (I prefer disposables, since a little bit of HCl seems to make its way inside, and it's easiest just to replace them) Always have plenty of water on hand (to slow-down possible renegade exothermic reactions, and also as an emergency rinse) Always pour acids into other liquids (both for splash reasons, and also to minimize the risk of an out-of-control exothermic reaction) Always use in a very well ventilated area Never heat the liquid. and last, and not least Make certain to wash your hands after using it, or you might accidentally rub some into your eye (which wouldn't be super serious, but would probably be pretty painful) At any rate, I recommend the HCl + Hydrogen Peroxide method to anyone that feels comfortable with the chemicals, and hates ferric chloride for all the reasons it should be hated (stains, hot liquids, unavoidable fumes, toxicity, etc...). In my opinion, it etches a lot better as well. Also, and I suppose FeCl will do this as well (and it surprises me that I haven't really read about anyone doing this, except for myself and George), but you can quickly etch labeling and center-points for holes on front panels with HCl on standard aluminum. RE: circular saws. I have an occasional drinking partner who is an emergency room doctor. After a few drinks I can get him to tell some horror stories (alcoholics with BACs that would kill a normal person, all manners of toiletry items being mis-inserted into all manners of orifices). Apparently carpentry related injuries are really common, because of saws, and planers (which he says just yank a finger off at the next joint). Finger injuries are difficult to repair with a low success rate, and this is compounded by the fact that many of the tools that make said injury will reduce the part it took off into a meatball covered in sawdust. So, there's a tool the hand surgeons will use if the finger is not re-attachable. It's called a bone nipper. It looks like a heavy-duty stainless steel version of certain types wire-cutters, and it's sole function is to nip-back the bone so that flesh can be stretched over the end of nub. Thinking about that really kinda runs chills down my spine. George: Keep up the gospel! Robin

Heheh, imagine my predicament, I ended up in a small electronics company (tube pre-amps mostly), and my training was in architecture. The whole electronics thing is coming slowly. As for now I'd happily trade my knowledge of building codes for a better way of etch-masking PCBs. Ok, so the problems we've been having with toner transfer are probably related to the toner we're using, or the paper. Hmmmm. Guess it's time to go shopping. But looking at your... umm... PCB manufacturing setup proves that we should experiment with toner transfer until we get it to a consistently high quality level. Otherwise I think we'll try putting photo-mask film onto bare copper board- so that we can have more control over the process. I've even considered putting in an order for a moderately sized medium-duty CNC machine to mechanically etch PCBs (and front panels)- but that'll cost us several thousands of dollars, which means it'll be that much harder to get a pay check. Speaking of panels, I'm not sure if you'd be interested in this, but- you can use HCl to etch aluminum. What you can do, is carefully apply a negative mask to an aluminum panel, use masking tape to mask-off the edges and back of the panel and to touch-up mistakes, and give it a dip for a few minutes. BE CAREFUL. The reaction that dissolves copper is nothing compared to dissolving aluminum, where (especially if you're etching a large surface area) the reaction can become violent as 3HCl + Al = 3H + AlCl3. In other words.... No smoking. The solution will actually appear to boil as Hydrogen is released. But the results are pretty nice looking. robin

George- Ok, apparently you must not store mixed etchant, it gasses- even when bottled up- enough to possibly break the bottle it is in. If I were you, I'd find a careful way of disposing of that bottle you have around... Sorry, I just happened upon this information. Hey- what method did you use for masking your board?? We're revising our method, and I'm researching every technique under the sun. Typically we've been using boards that have a pre-sensitized positive photo resist on it, but... advantages: -Easy, and at least the exposure & developing are pretty consistent. disadvantages: -boards seem to only be available in 1oz 1/16", and not available in large sheets. -quality of the boards seem to vary wildly from manufacturer to manufacturer- the tell-tale sign of a crap board is when grooves following the top-grain of the fiber-glass etch out several minutes before the rest. But also the handling of the board from the manufacturer until the time of development seems to be important- and partially beyond our control, often times if the boards were roughly-handled in the mail scratches will show up during development. -boards are costly -we're not really sure if it's because of the thickness of the copper, the thickness of the etch-resist, or that we use a flourescent bulb instead of a point-source, but it rarely produces really crisp edges, at least on the entire board, which makes it unsuitable for SMD work. -time consuming (9 minutes for exposure, 10-ish minutes to develop. We've recently tried toner-transfer.. using both specialty decal paper and plain paper, also with and without foil. Advantages: -Consistently produces edges that are as crisp as your artwork. -Plain paper is about as cheap of a way to do this as I can envision there being. -plain clad board can be bought in nearly any size, thickness, and copper-weight that exists. -plain clad board is also cheaper for the above reason (we have a small, as in miniscule, business- and having things that are cheap and readily available is the name of the game) Disadvantages: -The decal paper hates our laser printer, when set to maximum toner-density (little flecks of toner get taken off the image and end up down the page). -The Kinkos down the street uses a toner composition that refuses to adhere to the copper. I watched in horror as the resist for the traces simply lifted up and floated away half-way through an etch. -The toner is semi-porous, so what at first may look like a perfect etch, when given the through-light test reveals a starscape of pinholes. This simply is unacceptable for any board that will be leaving the workshop.

Yeah, I guess I should switch brands of cigarettes :) Therezin: Hey thanks. I'll look up the info on the web, but I think I have a bottle of zinc tablets somewhere. I've caught my partner holding stips of solder in his mouth before (it's the whole not having 3 hands thing. The panavises and hemostats make it a little easier, but sometimes you just need an extra limb...Personally I'll go for a shady solder joint before I do something which is clearly damaging)- I should require him to take these zinc if what you say is true... robin

You know, I've been worrying about solder. My partner and I recently switched back from ROHS compliant stuff (it can be a real pain to use, is real finnicky, has a higher melt point, doesn't produce as many shiny joints as lead solder, and it's an absolute b*tch for soldering big connections). We can pretty easily go through a half pound of the stuff in a weekend making tube-gear. I swear one night after leaving the workshop my lips were tingling. Did I mention that we chain-smoke while we solder? I dunno. Hopefully I won't end up stunted, and my future children will be alright. As far as etching methods: Carsten: I understand if you have reservations concerning the various etching methods. The methods take a bit of trial-and-error to get half-way decent results from, and almost all of the chemicals involved are toxic and or corrosive/caustic. None of this is stuff you should be doing in a dorm room anyways (sorry for being presumptuous about your living situation/ for that matter you could be a professor for all I know). If you're only doing MBHP stuff, why not send-off for the pre-made PCBs??? The stuff from Smash_TV is waaaay cheaper than anything you could do on your own (without already having the required chemicals/equipment)- and yes it might take forever and a day to arrive, but the PCBs he has made are of much higher quality than anything you're likely to make on your own, plus the kits come with the components. Really, I think this is the best solution for someone who clearly doesn't want to make their own (and realistically, probably the best solution for 90% of the people that DO want to make their own).

Ok, I guess this is an old thread that was sort of left on a cliffhanger... Stryd: Yeah, it's just the IC, but if I remember right it requires very few external components to drive it, and the slide surface is one that you specify, and of course, you'll have to etch PCBs for the electrodes...

George, First, your board looks great! Lately it seems like I've become the high-priest of hydrochloric acid on here, maybe I should direct people to your image... I've found that with about three cups of etchant I can etch 2-3 4"x6" boards before it starts to slow down too much. But then I just make a new batch :) Even if the etch is going kinda slow, with HCl it still etches pretty much uniformly. Unlike with FeCl where one side of the board will be completely gone before the other is done etching. The bad part is that the temperature has been dancing around freezing lately, and this seems to s-l-o-w the etch process down quite a bit... I have to do it outside as well. Maybe I can install a hood as a business expense... In the meantime the cold etch just gives me more opportunity to catch up on the important things in life, drinking and smoking. Robin

HCl isn't safe, but- the same precautions should be made with either chemical. You obviously don't want to ingest them in any way. You don't want to come in direct contact with either of them. Both put out some nasty fumes and should be used only under the best ventilation you can provide. My main complaints about the safety of FeCl is that... A> Without a bubble tank you're probably in more-or-less direct contact with the stuff (fumes and all) either sloshing a board back and forth in a bin of the stuff, or rubbing the board with a sponge soaked with it- both ways tend to get the stuff everywhere, on yourself, and on your workspace. Again, the only way to mitigate that is to have a bubble tank. B> It requires heating- which is dangerous for several reasons (electricity + electrically conductive liquids, burns, and the heating only makes it more noxious). Where-as HCl + H2O2 requires little to no agitation, and can be used at room-temperature. All this means is that you can start the etch process and step away from the dangerous chemicals. 3% H2O2 isn't particularly dangerous without being inventive- at that dilution you could probably even drink it if you don't mind sitting on the toilet for a couple hours. Not to mention that there simply isn't a good or at least practical way to dispose of FeCl (how many of you actually have a hazardous waste disposal company come pick it up??? Now, how many of you have dumped it down your sink, or on the lawn??)... HCl, while being a strong acid, isn't particularly toxic and can be poured down the drain or dumped in the yard in reasonable quantities. But obviously, people should use whichever method they like most, and you should be able to comfortably handle chemicals to use either process- especially when dealing with strong acids (though I'm willing to bet that if you're using a photo-mask, you're also using NaOH as a developer- which is very caustic, and could blind you as easily as it would clean your oven). Personally, I don't like dealing with FeCl for the above reasons, and I seem to have better and faster etches with HCl. The Gyraf Audio (gyraf.dk) website has a primer on using it (though I like to use a more dilute solution to prevent over-etching as well as for safety reasons) that piqued my interest a while back- now we use nothing but HCl + H202..

Hey George, The HCl + H2O2 etchant, just like ferric chloride, will lose it's ability to dissolve copper (or any metal) as it reacts to form cupric chloride. BUT, as far as just sitting on a shelf.... I would think that the shelf life of the stuff would be on the order of a few months. The hydrogen peroxide will decompose into water and hydrogen with time, even if there's nothing to react with. I don't think it'd be possible to actually ruin a board by using "expired" etchant.. It would just sit there... and not much would happen. On the other hand, it's been years since I took a chemistry class- and half the point of using this method is that the etchant is dirt cheap and disposable... Good luck, and tell me how it's working out with your pcbs Robin

I posted a method for etching with HCl and H2O2 several weeks ago. I know that there has been a little talk on here about it before as well. I also know that a lot of people frown upon this method, and the only reasons I can find for it is that A> It uses dangerous chemicals (as if ferric chloride is particularly safe) B> It's easy to over-etch if your solution is too strong, or if you use the "sponge" method common with ferric chloride. So, use common sense with this method, you absolutely have to do this outside, under a hood, or in a large room with amazing ventilation. You absolutely have to wear eye protection- if you get HCl in your eyes, you *will* have to visit the hospital. You also have to be careful not to splash yourself with the etching solution- it won't be strong enough to instantly burn you, and having given myself chemical burns before, you'll know it's happening when you get this weird painful itch. But plenty of water, and replacement gloves will fix that. The two main dangers are: A> inhalation of HCl fumes (it can break down into chlorine gas), the stuff is really noxious, but if you perform the etch outdoors- you should be fine presuming that you aren't standing over the etch pan. B> too strong of a reaction, again, I recommend against using 40% H2O2 for this reason, and to either use regular store-bought (3%) or to dilute the 40% down to under about 7-8%- though the 3% H2O2 is easy to get, has never led to a run-away reaction, and makes the etch time a bit more manageable (in fall weather, the etching seems to take between 15 and 30 minutes) Anyways, in a runaway reaction, since this is an exothermic reaction, the etch solution can get hot enough to boil- in which case the best way to bring it back under control is to add water to the etchant. If you feel comfortable with the risks, I'd suggest trying the HCl + H202 method. Despite all of the caveats I've listed, I find it to be a bit more reliable, less finicky, less expensive, less time-consuming, and (if handled correctly) less dangerous than the ferric chloride method. I've never tried the ammonium persulfate etch before though. I'm curious, but, the HCl method hasn't done me wrong yet. About PCBs versus the various proto-boards: Having a well thought out PCB will always be worth the effort. Design takes a bit of time and expertise, but should be within the grasp of anyone who would seriously sit down with a schematic and a protoboard. For simple designs I draft them up in Autocad Mechanical, or course you'll have to know your component spacings before hand. More complex designs have to be done in something like Eagle (which invariably I have to send back through autocad, since I find eagle kinda retarded for drafting). But I've known people that have successfully generated PCB artwork in Adobe Illustrator even. Advantages of PCBs: -very few jumpers, which makes trouble shooting a LOT easier. -correct spacing and pin layouts for components, which means that you have fewer jumpers (which can short, wiggle out of position, and are just plain visually confusing), or that you don't have to 'make it fit'. -logical layout -more reliable -and the aesthetics are just plain better- even the best looking protoboard project pales next to an average PCB Disadvantages: -Manufacturing (expensive to send-off, or requires setup for masking, etching, and drilling) I have a small boutique audio company, and we can have a board exposed (about 30 minutes, including exposure time, developer time, and proofing), etched (again, about 30 minutes, though it's good to take the board out part-way through, rinse it, and with magnification double-proof the circuit before completing the etch), and drilled (this can take between 10 and 45 minutes, depending on the size of the board, and how fast you are) in well under 2 hours. more like an hour and a half. A lot of time is spent on proofing, and this is one of those things- it's a pain, and it's time consuming, and the surgeon glasses I have hurt my eyes, but every minute spent proofing will save you the that amount times 10 down the line. Again, this is well within the capabilities of anyone with some experience in electronics, a basic understanding of chemistry, time to make a mistake or two while learning, and a hundred dollars for supplies: drill accessories (either use a tabletop drill, or a small hand-operated jewelers drill, with *steel* bits), exposure lamp, boards, chemicals, gloves, eye-wear, dishes, x-acto knife, the trusty sharpie marker, and a can of clear acrylic spray. anyways.. good luck

One of the best looking bits of DIY kit I've seen. Congratulations. Monolake Rulz!

I first discovered this at the gyraf.dk website (the DIY section has tons of great stuff including some nice tutorials). I always seem to have bad luck etching with ferric chloride, and it seems like I'm always out- which means I either have to order it (and wait a week), or go to radio shack and pay $$$$ for their brand. But there is another way, it's cheap, easy, does a good job, and the chemicals are readily available.... Instead of using ferric chloride, I started using hydrochloric acid (approx 50% solution) and hydrogen peroxide (3%, the same stuff at the drug store). Hydrochloric acid is sold as muriatic acid in hardware stores as a cleaner, and I bought two gallons for four dollars and change. Procedure: as opposed to the procedure on the Gyraf Audio website (which is good, but requires a form of hydrogen peroxide that is hard to find, and depending on where you live- illegal to transport), I used a 1:1 ratio of HCL and H2O2, this seemed to work well. What you need: HCL 50% (or close to 50%, sold as Muriatic acid) H2O2 3% (sold as antiseptic) WATER! (Enough for the rinse, and a jug on hand... Just in case, see below) 2 PYREX measuring cups (one for each chemical) 2 PYREX pans (one for etch, one for rinse) SAFETY GOGGLES DISPOSABLE GLOVES First of all, you absolutely have to do this outside. The procudure can develop chlorine gas. I'd recommend even having a portable fan on hand to blow away the fumes. You Absolutely must wear safety goggles. This stuff will F-you up if you get it in your eyes. You must wear disposable gloves. I say disposable, because there is a good chance that some of the acid will find its way down into them, this is not a huge problem, you will know that this is the case way before you have a serious burn, but it's easier to mitigate this risk by having plenty of disposable gloves. The etching reaction is exothermic- this means that it produces heat, though it's unlikely, there is a chance that the etching solution could get hot enough to actually boil- you'll know that it's about to do this if it starts fuming a lot. If this begins to happen, slow down the reaction by CAREFULLY pouring water into the etching solution. I used a 13"x8" dish as my etch, and one significantly larger as my rinse. Into the etching dish I measured, then poured 1.5 cups of H2O2, and then did the same for the HCl. ALWAYS (except in the above exothermic-doomsday scenario) pour acids into water, not the other way around. This minimizes the risk of splashing yourself with a very very corrosive substance. The actual amount etchant isn't that important, what is important is that it's about a 1:1 ratio, and that it only filled the dish up about half-way. CAREFULLY slide the PCB into the solution (it'd be a good idea to have the first edge to go under- towards you, as to minimize the risk of splashing). Immediately, the un-masked copper will turn a dull yellow-orange color, and bubbles should soon start to form. I'd recommend manipulating the etch as little as possible (no sponges, no rubbing, and definitely no toothbrushes- all of these things will ensure that the edges of your traces will start to dissolve). The rate at which it etches seems to be dependent on the temperature, the first time I tried it, the etch took about 5 minutes, though it has cooled off a lot since then, and the last etch I performed (at about 45 degrees farenheit) took closer to 30. If it is etching really slow, it seems to help to gently rock the solution back and forth over the board. Cleanup: HCl and H2O2 are both relatively safe to the environment. There will be a little bit of copper dissolved in the solution- which isn't the best for the environment, but, at the very least this stuff can be thrown down the sink without too much of guilty conscience. If you wanted to be extra safe, you could try to neutralize the HCl with NaOH (which you probably have as your pcb photo-developer), this should form salt water- which is of course, safe to flush. Anyways, I feel liberated with this method. The chemicals are easy to get, and cheap, the quality of the etching I've performed with it has improved dramatically. It's safer for the environment, and on-average seems faster too.

If sheilding is an issue (which it will be, if it's in the same box), try finding a toroidal transformer instead.

I could be wrong, but, it's my understanding that the solders that are based on a conductor in some sort of binder (such as conductive epoxies) are ok for small jobs and repairs, but add impedence to a circuit. So.... Based on that, again, it would be ok for small jobs/repairs, but not so good for an entire board.

Fortunately all of the work we printed was passed before about 8 pairs of eyes before it'd make it to print, so things like spelling mistakes were never an issue. But certain things could only be caught at time to set up the press, things like mis-registration of the artwork (it's rare, but it has happened), skewing of a panel during exposure, the occassional screen that would get over/under exposed (usually just enough to make whatever 6-color job it was part of look really weird), etc.... This isn't really a mistake, but, we had to have a meeting one day, the shop foreman/supervisor/whatever sat us down... "Guys, we have this new client, and she's a really nice old lady and doesn't understand, but the job name is 'Spunkwear'.... <everyone starts laughing>... So just don't write anything on the job tickets in case she ever sees one or shows up, Ok??" For you non U.S. people, spunk is a sometimes slang-word for.... ejaculate. And then there were all of the death-metal t-shirts and stickers we did... But yeah, don't pull a rave-flyer, triple check your spelling before you burn any screens.