OK, a lot of you have wondered why I advocate the use of single-sided PCB. Let me justify my opinion.
When you work with DIY PCB's enough you realize kinesthetically that you can't geometrically wire up a real board with just one side (the reason why motherboards even have more than 2 "sides"...they laminate several layers together giving more "sides"). Especially with multiline busses. However you'll find you can usually circle them around in such a way that you only need a few jumps to get finicky ones hooked up (like from one side of the board to another, or to pass a single line across a bus of lines). What you do in your drawing program is you make a connector pad circle and you put "J#" next to it in copper. Then you do the other jumper the same way with the same jumper number (so you know at assembly time exactly which pads you are jumping). Then you take a piece of insulated, end-stripped wire and you run your jumpers on the top side of the board, snaking it around the components. The problem with double-sided presensitized is that its pretty advanced to get the two sides to line up with the level of registration you need every time. The funny part about this is that the problem is the little whiff of air that slightly shifts your transparancy mask just a fraction of a millimeter when you drop the lexan on it, during exposure. Can you do it? Yes, of course, But its another skill to learn. To do this you just put circles with crosses through them and you line them up like crosshairs. NEXT STEP How do I complete my DIY PCB Board? Here are the steps: board cutting, drilling holes, mounting components, soldering, and cutting your leads. Board cutting You will probably want you board a certain size different than the presensitized blank. You can also etch multiple boards and sub-boards on the same blank. So you can case it, etc. etc. My opinion: chop saw with abrasive circular blade. Why? You can band saw it but you can't get it perfectly straight. A cut on a chop saw takes about 5 seconds to line it up perfectly and cut a perfectly straight cut at 90 degrees. Can I use a Dremel tool? Honey, this is America, you can do whatever you want :D This approach is appropriate for enthusiast/serious hobbyist. Etch single-side bottom, then jumper the finicky ones on the top side. Anything else just wouldn't be civilized. Drilling Holes As far as I'm concerned THE way to do it is with a Fiscars drill and precision bits (Harbour Freight - $8 for a set). You just palm the drill, insert the bit and hand tighten. You will find that your copper connector pads accept the precision bit perfectly Drill ALL the holes in the board in one operation. Tape or clamp the board to a sacrificial piece of plywood or just wood. For larger mounting holes just use your regular bits in the Fiscars. Mounting components Break out your tackle box or mouser package and lay out everything you need. You will need a scrap of paper with the resistor band colors on them. The rest of the components have their values on them. Don't cut the leads yet, it'll look like a porcupine when you are done but just insert the part and bend the leads outward to keep them on the board. One operation. Soldering Use a nice hot soldering iron (just be careful).make quick contact with point with both lead and copper-clad and touch the solder to the point where they all meet. You'll be an expert in about 2 minutes. I use a desoldering hand pump (spring driven) for mistakes. Lead cutting. Use a pair of "dikes". This is one of the tools you don't want to skimp on...an actual set of dikes with a spring. $2 at Harbour freight about the same size as your hand (not wire cutters...you'll find out why). <https://lh3.googleusercontent.com/-_w6yTQYpZ_8/WJPDeHmlI4I/AAAAAAAAAFE/l2-Ty1MsXKsY2G7rsI_J9ak1XA7aFSs_ACLcB/s1600/dikes.jpg> This IS a set of dikes. Small, precise and spring-loaded. Cut all the leads in one operations. You are done. You now have a perfect DIY board. Addendum: Casing Get plastic case. Mount with screws and nuts (maybe with standoffs). Cut large holes, sharpy marked, with dremel cutting wheel (clean up with barrel sander bit). Circular holes Fiscars/Bit. Remember that switches, LED's, wire, all fit perfectly through drill holes. Strain-relieve by just a knot on the inside of the case. Casing also drastically cuts down on ESD, a real concern with today's hobbyist electrons. My BBB cost me landed $80...I can't afford a bricked component this expensive even localized burn-outs on my p8/9 so I case ASAP. On Thursday, February 2, 2017 at 2:09:39 PM UTC-7, woody stanford wrote: > > OK, here is a short primer on how the good guys build things in a serious > hobbyist setting. > > The development is done in 2 main stages. Breadboarding, and PCB > construction (with presensitized board). > > The reason why the breadboarding phase is because the Inet is great, but > you can't believe everything you read on it. What you want to do is look on > the WWW for ideas and then breadboard them out. Once you get them reliable > and you undersand their operation, you can use the technique in your > personal projects. > > How you do this on a budget (as it is the Great Recesion) is you get cheap > Chinese breadboards on ebay for $5 a piece free shipping. Like here, > > > http://www.ebay.com/itm/830-Tie-Points-Solderless-PCB-Breadboard-MB102-65Pcs-Jumper-cable-wires-/231412564779?hash=item35e143832b:m:mlV4jkc4DpzzqjQsn-zO0-w > > The latest and greatest idea, the only downside is that it takes longer > than a week to get your stuff in but the price is right. You can also get > broken out sensors and the like for dirt cheap (basically mounted great > stuff the big guys use in smart phones and tablets). $5 per component is > typical if you know where to go. > > What you do is peal the backs off them an mount them to a 2' x 2' piece of > plywood you can get at Home Depot. And you are ready to rock. next step is > to find inexpensive, reliable power. A cool thing I've been playing with is > tablet bricks because they are reliable, ubiquitous and a lot of them > deliver a strong 1.0 Amp or 5VDC. Take your soldering iron, figure out the > GND and the +5VDC and you have comfortable power on the 1 amp range. As > always, PC switching power supplies are great too (just get a $5 DMM from > Harbour Freight and sacrifice its leads so you have a constant digital > power monitor....solder it on and wrap with electrical tape). > > What you do is you mount everything on your plywood. You take your > Fiscar's drill (with $2 high-speed steel Harbour Freight drill bits) and > you get a nice selection of dollar-store machine screws (and nuts) that > you've "tackle-box-ized". Shop the 99 Cent Store for these cheap tackle > boxes and pick up about a dozen of them to keep your stuff in (resisters, > relays, diods and voltage regulators). The trick with this is: mouser, but > listen...you can get premade kits for around $70 but they have less than $5 > worth of parts in them. What you want to do is put them together yourself > and when you get low on standard parts (like certain resistor values) you > just restock. All it takes is time to build these part kits, you put > together generic BOM (bill of materials) for your tackle box kits so you > have a nice selection of standard caps, diodes, transistors, MOSFETS, tiny > relays, optoisolators, MCU's like PIC's and of cource exotics like NEO6M's, > preprogrammed MCU's, and MCU6050's. > > Modern hacking requires attention to ESD (electrostatic discharge) because > a lot of your stuff has sensitive digital logic in it. The fix is basic. > Take a piece of silver solder and stick it in your ground power rail so > about an inch of its hanging out. Every time you get up to walk around > (where you accumulate chip-killing static) when you sit back down, just run > your finger unconsciously across the solder tail. You are now grounded. > Formal ESC with a wrist strap is ok too. But don't wire yourself to ground > btw as this can lead to you doing an impression of a light-emitting > resistor (an old joke but a good one); think about it electrically. > > OK, you BBB (in my case my BBBW), what you want to do is mount everything > to your plywood so when the wife says playtime is over, you can just put it > up. Also, claiming a second "junk drawer" in your kitchen is a life-saver > specifically for all your little tools and tackle boxes.What you do is you > get > > *** STANDOFFS *** > > To make standoffs you get a length of small-dimater ridged plastic tube > and you cut pieces off yourself (getting them from Home Hardware is > expensive) One of my little secrets. > > To attach your BBB to the plywood, mark the holes with a fine Sharpy, load > your bit in your Fiscars (at a slightly smaller diameter than the screw you > will use) and just sink a hole half-way through. Then take handful of > screws, a few standoffs and mount your BBB in a majestic location on your > plywood. Takes like 30 seconds and its secured for weeks of tinkering. > > Cut lengths of SOLID CORE insulated wire and strip the ends with a solid > professional grade wire stripper (they are cheap and so worth it). Now you > have all the wire you will ever need. First step with it is to wire your > breadboards power rails. Connect all the blue (or GND) rails with insulated > wire and what I do is run 3.3V on the left rail and 5V on the right rail > (because I'm working a lot of times with both BBB and TTL), but if just > working with 3.3V parts you can wire all your rails 3.3V to cut down on > confusion. > > You can do strain-relief by just knotting the power cord or whatever > through a hole in your plywood. Keeps you from jerking sensitive wires and > cables loose when moving around. > > THE PLAN > > OK, what you do is you experiment on your breadboards connecting > everything with wire. We all know how to do this. Get a complete working > version of the circuit(s) on your breadboard set up. This will become your > master reference for the next step: DIY PCB construction. > > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/4c8cec60-24c2-43e7-91e8-d574987669b3%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
