Vintage Headphones Bluetooth Conversion Goes The Extra Mile

July 9, 2018 by Ben James 2 Comments

[KaZjjW] wanted to retrofit a pair of nicely styled vintage headphones to be able to play wirelessly over Bluetooth. In principle this is an easy task: simply stick a Bluetooth audio receiver on the line-in, add a battery, and you’re all set. However, [KaZjjW] wanted to keep the aesthetic changes to the headphones at an absolute minimum, retaining the existing casing and volume control, whilst cramming the electronics entirely inside and out of sight.

With the inherent space constraints inside the cups of the headphones, this proved to be quite a challenge. The existing volume potentiometer which hung half outside the case was remounted on an ingenious hinge made of two PCBs, with the pot floating next to a surface mounted switch. This allowed it to not only control the volume, but also act as an on/off switch for the Bluetooth. The only other existing cuts in the casing were a circular hole for the audio cable, and a slit for the cable strain relief. These worked perfectly for an LED status indicator and micro-USB battery charging.

The main chip used for receiving audio over Bluetooth was the BM62 by Microchip. It’s a great all-in-one solution for this kind of project as it has built-in battery charging, an on-board DAC and audio amp, as well as a serial control interface. In part 2 of the project log, the process of programming the BM62 was documented, and it was painful – it’s a shame that the software support lets it down. But a hacker will always find a way, and we’ve seen some pretty neat hacks for reprogramming existing chips in off-the-shelf Bluetooth headphones.

Two PCBs for the pot button hinge, one for the LED and micro-USB connector, as well as one for the Bluetooth receiver and a PIC. That’s four PCBs in a pretty small space, enabled by some commendable design effort both electronically and mechanically. It certainly paid off, as the finished product looks very slick.

Continue reading “Vintage Headphones Bluetooth Conversion Goes The Extra Mile” →

Multi-Board Solder Stencils Explained

July 7, 2018 by Jenny List 13 Comments

There was a time when reflow soldering was an impossibly exotic process at our level, something that only the most superhuman of hackers could even dream of attempting. But a demystification of the process plus the ready availability of affordable PCB and stencil manufacture has rendered into the range of almost all constructors, and it is likely that many of you reading this will have done it yourself.

Screen-printing solder paste onto a single board presents a mild alignment challenge, but how about doing it with many boards at once? [Eric Gunnerson] had this problem with a small-volume board he’s selling, and not being in the happy position of having his PCBs supplied on a panel, had to create his own multi-board alignment jig and stencil. His write-up provides a comprehensive and fascinating introduction to the process whether you are an occasional dabbler or embarking on a production run as he is.

The problem facing any would-be stenciler is that the board has to be held in place reliably in the same alignment as the stencil. With a single board, it’s easy enough to do the usual thing of taping scraps of PCB board to constrain its edges and hold it in place as a rudimentary jig, then lower the stencil onto it. Perhaps you’ve used one of those commercial stencil jigs, in which a set of magnets hold the stencil in place, or maybe you use pins to line everything up.

[Eric] takes us through the process of creating a laser-cut alignment jig for twelve boards, and cutting a matching twelve-board stencil. This includes all the software side using Inkscape, the selection of materials to match PCB thickness, and some of the issues with cutting Mylar sheet for the stencil without shrinkage at the corners. He’s using pins for alignment, and he even finds a handy supply of those in the form of shelf support pins.

We’ve visited the world of reflowing many times before. If you’d like a primer, here’s our Tools of the Trade piece on it, and if you aren’t daunted by larger projects, here’s an account of a prototype run of a significantly complex board.

How To Design Custom Shaped Boards In Fritzing

July 4, 2018 by Brian Benchoff 18 Comments

If you’re looking to get started in designing a few PCBs, you could use one of the many software packages that allow you to create a PCB quickly, easily, and with a minimum amount of fuss. You could also use Fritzing.

Fritzing is terribad and you shouldn’t use it, but that doesn’t mean you still can’t abuse Fritzing to make it do what you want. [Arduino Enigma] recently posted a tutorial on how to design custom PCB shapes for Fritzing. Yes, Fritzing is no longer limited to rectangular PCBs with sharp corners. You can make PCBs in any shape with Fritzing, provided you spend a few hours futzing about with Inkscape.

The goal for this project was to create a rectangular board without any sharp corners for [Arduino Enigma]’s Sinclair Scientific Calculator Emulator. Fritzing can make a board in the shape of a rectangle, in fact, that’s all it can do, but [Arduino Enigma] wanted a rectangle with radiused corners. After hours of work, we have the writeup on how to do it.

The imported board, with 3mm radiused corners.

The process to create a custom-shaped board, in this case, a rectangle with a 3mm radius on the corners, is simple. First, draw a rectangle of the desired shape, then draw even more rectangles as a sublayer of the current layer. Fritzing requires the layer ID to be named ‘board’, ‘silkscreen’ and ‘silkscreen0’, but this cannot be changed in Inkscape itself — you’ll need to edit the file with a text editor. After creating three layers, each containing the shape you want, simply trim the size of the page to the size of the board. Save the file, edit the file in a text editor, and click save. Launch Fritzing, load an image file, and select the SVG you’ve been working on. In just twenty or thirty quick steps, you too can import any shape you can imagine into Fritzing.

There is one pain point to this process. Editing the layer name manually with a text editor pushes this Fritzing hack from a baroque workaround into something that makes us all question the state of Open Source standards. Unfortunately, this is required because Inkscape does not use layer names as the ID in an SVG file. No, it doesn’t make sense, but that’s just the way it is.

For any other PCB design tool, creating a custom-shaped board is simply a matter of drawing a few lines. Fritzing is different, though. The top copper layer is represented as orange, and the bottom copper layer is yellow, a UI decision that doesn’t make sense, even if you aren’t colorblind. Putting more than two layers of copper on a Fritzing board is impossible. Fritzing is a tool you should avoid for PCB layout. That said, [Arduino Enigma] figured out how to do something in Fritzing that you’re not supposed to be able to do and that’s pretty cool.

Nonpareil RPN HP-41 Calculator Build

July 4, 2018 by Rich Hawkes 21 Comments

The early HP Reverse Polish Notation calculators have a special place in the hearts of engineers and tinkerers as there are lots of projects involving them. They haven’t been produced in decades, but [Chris Chung] has used some open source code to create DIY hardware version of the HP-41 Reverse Polish Notation (RPN) calculator.

The open source code behind the calculator is the Nonpareil High-Fidelity Calculator Simulator, and [Chris] has used it along with a custom designed readout and PCBs to create a working prototype. The simulator uses the original byte code of the HP-41 so the its behavior is exactly the same as the original calculator.

[Chris] has designed the PCBs so that the buttons and the screen are separate and join together. This neat idea means that he can try out different screens or different button PCBs and mix-and-match to find the combination that works best. He’s also designed a 3D printed case for the calculator. He does prefer using the bare buttons on the board to the 3D printed ones he printed for use with the case.

We love calculators here so there have been a bunch of articles over the years. Check out the documentation that comes along with this open source calculator, or check out this pocket calculator that emulates two other pocket calculators!

Continue reading “Nonpareil RPN HP-41 Calculator Build” →

PCB Holder Quick-fix Turns Out To Be Big Improvement

July 1, 2018 by Donald Papp 15 Comments

When something needs improving, most hacks often make a small tweak to address a problem without changing how things really work. Other hacks go a level deeper, and that’s what [Felix Rusu] did with his 3D printed magnetic holders. Originally designed to address a shortcoming with the PCB holders in his LE40V desktop pick-and-place machine, they turned out to be useful for other applications as well, and easily modified to use whatever size magnets happen to be handy.

The problem [Felix] had with the PCB holders on his pick-and-place was that they hold the board suspended in midair by gripping the sides. The board is held securely, but the high density of parts on panelized PCB designs leads to vibrations in the suspended board as the pick-and-place head goes to work. Things are even worse when the board is v-scored for the purpose of easily snapping apart the smaller boards later; they sometimes break along the score lines due to the stress.

Most people would solve this problem by putting a spacer underneath the board to stabilize things, but [Felix] decided to go a level deeper and change the mounting system altogether with a simple mod. The boards now lie on a flat metal plate, and his magnetic holders are simple to make and easily do the job of holding any size PCB secure. As a bonus, it turns out that the holders also do a passable job of holding work materials down on a laser cutter’s honeycomb table. A video overview is embedded below, and the design files are available on Thingiverse.

Continue reading “PCB Holder Quick-fix Turns Out To Be Big Improvement” →

Computer Vision For PCB Layout

June 12, 2018 by Al Williams 31 Comments

One of the big problems with doing PCB layout is finding a suitable footprint for the components you want to use. Most tools have some library although — of course — some are better than others. You can often get by with using some generic footprint, too. That’s not handy for schematic layout, though, because you’ll have to remember what pin goes where. But if you can’t find what you are looking for SnapEDA is an interesting source of components available for many different layout tools. What really caught our eye though was a relatively new service they have that uses computer vision and OCR to generate schematic symbols directly from a data sheet. You can see it work in the video below.

The service seems to be tied to parts the database already knows about. and has a known footprint available. As you’ll see in the video, it will dig up the datasheet and let you select the pin table inside. The system does OCR on that part of the datasheet, lets you modify the result, and add anything that it missed.

Continue reading “Computer Vision For PCB Layout” →

Scotty Allen’s PCB Fab Tour Is Like Willy Wonka’s For Hardware Geeks

June 12, 2018 by Mike Szczys 23 Comments

The availability of low-cost, insanely high-quality PCBs has really changed how we do electronics. Here at Hackaday we see people ditching home fabrication with increasing frequency, and going to small-run fab for their prototypes and projects. Today you can get a look at the types of factory processes that make that possible. [Scotty Allen] just published a (sponsored) tour of a PCB fab house that shows off the incredible machine tools and chemical baths that are never pondered by the world’s electronics consumers. If you have an appreciation PCBs, it’s a joy to follow a design through the process so take your coffee break and let this video roll.

Several parts of this will be very familiar. The photo-resist and etching process for 2-layer boards is more or less the same as it would be in your own workshop. Of course the panels are much larger than you’d ever try at home, and they’re not using a food storage container and homemade etchant. In fact the processes are by and large automated which makes sense considering the volume a factory like this is churning through. Even moving stacks of boards around the factory is show with automated trolleys.

Six headed PCB drilling machine (four heads in use here).

What we find most interesting about this tour is the multi-layer board process, the drilling machines, and the solder mask application. For boards that use more than two layers, the designs are built from the inside out, adding substrate and copper foil layers as they go. It’s neat to watch but we’re still left wondering how the inner layers are aligned with the outer. If you have insight on this please sound off in the comments below.

The drilling process isn’t so much a surprise as it is a marvel to see huge machines with six drill heads working on multiple boards at one time. It sure beats a Dremel drill press. The solder mask process is one that we don’t often see shown off. The ink for the mask is applied to the entire board and baked just to make it tacky. A photo process is then utilized which works much in the same way photoresist works for copper etching. Transparent film with patterns printed on it cures the solder mask that should stay, while the rest is washed away in the next step.

Boards continue through the process to get silk screen, surface treatment, and routing to separate individual boards from panels. Electrical testing is performed and the ~~candy making~~ PCB fab process is complete. From start to finish, seeing the consistency and speed of each step is very satisfying.

Looking to do a big run of boards? You may find [Brian Benchoff’s] panelization guide of interest.

Continue reading “Scotty Allen’s PCB Fab Tour Is Like Willy Wonka’s For Hardware Geeks” →