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).