Over the last few years we’ve seen a few commercial products that aim to put an entire PCB fab line on a desktop. As audacious as that sounds, there were a few booths showing off just that at CES last week, with one getting a $50k check from some blog. [Connor] and [Feiran] decided to do the hacker version of a PCB printer: an old HP plotter converted to modern hardware with a web interface with a conductive ink pen.
The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.
The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.
Continue reading “Circuit Plotting With An HP Plotter”
[John] has managed to replace a broken turn signal PCB by scanning it and converting to Gerber format. [John] purchased a Triumph Spitfire with toggle switch wired up for turn signal control. The “official” replacement part worked better than the toggle switch, but it didn’t cancel after turning. He was able to get the original switch, only to find it had a hole completely burned through the phenolic board. This isn’t completely surprising, as Triumph used a Lucas Industries electrical system. As anyone who has owned a car with a Lucas “prince of darkness” electrical system will tell you, Lucas systems were not known for quality. A quick Google search brings up plenty of pages attesting to this.
Phenolic resin/paper was a common early PCB material. The FR-4 fiberglass boards most commonly used today could be considered descendants of FR-1 and FR-2 phenolic. (The FR in this case stands for Fiber Reinforced). The standardization worked in [John’s] favor, as his burned board was 31 mils thick, which is still a standard PCB thickness. Re-creating an odd sized board such as this isn’t a hard job. It would however mean spending quite a bit of time with a ruler and a caliper. Rather than spend all that time measuring and re-drawing, [John] scanned his PCB on a flatbed scanner. He used graph paper as a background to verify the image wasn’t being stretched or skewed.
[John] brought his scan into inkscape, and traced both the outline and copper areas. The outline and copper had to be exported as two separate files, so he added corner marks outside the board outline as fiducials. He then used pstoedit to convert inkscape’s eps output files to gEDA pcb format. The two files were rejoined in gEDA. From there [John] exported a Gerber, and ran it on his home PCB milling machine. The results look good. [John] plans to make another revision of the board from a professional PCB house with vias to hold the copper to the substrate.
It’s not totally fair to say that this project is just getting under way. But the truth is it neither picks nor places so there’s a long road still to travel. But we’re impressed with the demonstrations of what [Daniel Amesberger] has achieved thus far. Using the simplest of CNC mills he’s finished the frame and gantry for the device. You can see some of the parts on the left after going though an anodizing process that leaves them with that slick black finish.
The demo video shows off the device by driving it with a joystick. It’s fast, which gives us hope that this will rival some of the low-end commercial pick and place machines. He’s already been working on the software, which runs on a mini ITX form factor computer. This includes a gerber file interpreter and some computer vision for a visual check on part placement. He hasn’t gotten around to building the parts feeders but we’ll keep you updated as we hear back from him.
Continue reading “DIY Pick and Place just getting under way”
We all know that Eagle has its share of shortcomings. Instructables user [westfw] was particularly annoyed by the fact that while Eagle keeps copies of up to 10 revisions of your board, it cannot open those files without resorting to manually renaming each one. Even more frustrating to him is the fact that you can’t use Eagle to view two files simultaneously in order to compare layouts. This made hunting down changes quite tedious, so he started looking for a better way to do things.
While using his favorite open-source gerber viewer gerbv, he noticed that the application let him load multiple copies of the same layer, XORing the PCBs’ colors together. Realizing that with some clever color selection, he could use gerbv to automatically highlight layout differences, he set off to automate the process.
The resulting script works on any flavor of *nix, and should play nice in Windows under cygwin as well. The script reads through Eagle backup files, renaming them and tweaking the colors so that when XORed, they show up as bright red areas in gerbv. It’s a simple yet handy tool to have on hand if you happen to do a lot of PCB design.
Up to this point we’ve used Eagle CAD as our exclusive PCB design and schematic layout tool. But [Brian] has inspired us to try something different thanks to his KiCAD tutorial.
KiCAD is an open source printed circuit board design tool. Since we like to rock the Linux here at Hackaday getting our hands on this was as easy as:
sudo apt-get install kicad
The version in the Ubuntu 10.04 repositories is a bit older but seemed to work just fine. [Brian] jumps right in with one of our most dreaded tasks on Eagle, designing your own parts. He knows of a nice online tool for automatic KiCAD part generation and walks through the process of building a voltage regulator and importing it for use in your own personal library From there it’s off to layout a power supply schematic for a breadboard PSU. The lesson continues with board layer, as well as the process used for exporting data for PCB fab house. We think this tutorial works well if you’re already familiar with PCB layout using a different software package but it moves a bit fast if this is your first time.
KiCAD seems like a nice tool and we’ve heard from many advocates in the comments over the years. Look for our next PCB design to be on KiCAD as we just need to use it for a while before passing judgement.
Tired of making kindergarten macaroni art PCBs? Check your Gerber files before you send them off to a fab house with a Gerber file viewer. Viewplot , GerbTool’s Viewer , and FAB 3000 Free DFM are all free versions of for-pay software to view your Gerber files. If you use Windows and demo software, these are nice options. If not, you can use gerbv. Allied with gEDA, Gerbv is free, open source software that you can use to view all of your RS-274X Gerber files and Excellon-type drill files. Still being worked on with an active development group, gerbv does not have all the bells and whistles, it does have the ability to delete objects. Check it out after the break. Continue reading “Look at Your Gerber Files with Gerbv”
SparkFun has posted an excellent guide to the many different issues you could run into when you finally decide to get a circuit board professionally produced. We assume that most of you aren’t running a professional design firm and will appreciate these tips gleaned from years of experience. They provided a rule list, Eagle DRC, and CAM file to help you get it right the first time. The end goal is designing a board that won’t be prone to manufacturing errors. The tutorial starts by covering trace width and spacing. They recommend avoiding anything less than 10mil traces with 10mil spacing. For planes, they increase the isolation to 12mil to avoid the planes pouring onto a trace. They also talk about annular rings, tenting, labeling, and generating the appropriate gerber and drill files. SparkFun isn’t completely infallible though, and manages to produce a coaster from time to time.
SparkFun naturally followed up this strict tutorial with a guide to unorthodox header hole placement. If you want to learn more about Eagle, have a look at [Ian]’s overview of Eagle 5 and Ruin & Wesen’s layout videos.