Building Beautiful Cell Phones Out Of FR4

Over on, [bobricius] took this technology and designed something great. It’s a GSM cell phone with a case made out of FR4. It’s beautiful, and if you’re ever in need of a beautifully crafted burner phone, this is the one to build.

The components, libraries, and toolchains to build a cellphone from scratch have been around for a very long time. Several years ago, the MIT Media Lab prototyped a very simple cellphone on a single piece of FR4. It made calls, but not much else. It was ugly, but it worked. [Bobricius] took the idea and ran with it.

The technique that goes into building an enclosure out of FR4 is something we’ve seen before, but we haven’t seen much of it since. Our resident old-school hacker [Voja Antonic] wrote a guide last year on using FR4 as an enclosure. The process is relatively simple – just leave some exposed copper around the edge of a panel, clamp it at about 90 degrees, and solder it to the edge of another panel. Adding captive nuts, standoffs, angles other than 90 degrees, and interlocking panels are slightly more advanced techniques, but still simple to implement.

[bobricius] has a few more tricks up his sleeve for his next version of this DIY cell phone. The nice, but hard to source, display will be replaced with a Charlieplexed 22×5 array of LEDs on a custom board, and the phone will feature QI wireless charging. If you can’t wait, [bobricius] is even selling a few of the current PCBs up on Tindie.

Of course, all this work would be for naught if the phone didn’t actually work. It does, at least until 2G networks are turned off. You can check out a video of that below.

Filed under: Cellphone Hacks

SIM Card Connectors and White PCBs Make Huge LED Snowflakes Happen

[Mike Harrison] talked about designing and building a huge scale LED lighting installation in which PCBs were used as both electrical and mechanical elements, and presented at Electromagnetic Field 2016. The project involved 84,000 RGBW LEDs, 14,000 microcontrollers and 25,000 PCBs. It had some different problems to solve compared to small jobs, but [Mike] shared techniques that could be equally applied to smaller scale projects or applications. He goes into detail on designing for manufacture and assembly, sourcing the parts, and building the units on-site.

The installation itself was a snowflake display for a high-end shopping mall in Hong Kong in the 2015 Christmas season. [Mike] wanted a small number of modular boards that could be connected together on-site to make up the right shapes. In an effort to minimize the kinds of manufacturing and parts needed, he ended up using modular white PCBs as structural elements as well as electrical. With the exception of some minor hardware like steel wire supports, no part of the huge snowflakes required anything outside of usual PCB manufacturing processes to make. The fewer suppliers, the fewer potential problems. [Mike] goes into design detail at 6:28 in the video.

For the connections between the boards, he ended up using SIM card connectors intended for cell phones. Some testing led to choosing a connector that matched up well with the thickness of a 1.6mm PCB used as a spacer. About 28,000 of them were used, and for a while in 2015 it was very hard to get a hold of that particular part, because they had cleaned everyone out!

Basic Snowflake Pattern A small number of different modular PCBs made up the bulk of the installation. With the exception of some formed steel wire for support, all parts were made using normal PCB manufacturing methods. In between each of the visible rivets is a SIM card connector taking care of the contacts between boards.

About half-way through the video (10:55) [Mike] goes into microcontroller and firmware details. The PIC12F1501 turned out to be a great fit for reasons that included cost, wide operating voltage range, 10-bit PWM for each of Red, Green, Blue, and White, and the low cost of having Microchip program the firmware in at the factory. RGBW LEDs were chosen for a number of reasons, but mainly because the white generated is much more visually consistent across a large display (compared to lighting each of the RGB elements to make white.) He made sure that it was easy to reprogram the firmware across all units easily if needed, because updating thousands of microcontrollers one at a time is just not an option.

Video of the presentation is embedded below, but if you want to go straight to some video of the finished installation, it starts at 21:38.

Using PCB material as a structural component has a lot of potential. We’ve seen it in this clever tiny 7-segment display, and more recently in PocketNC’s FR4 Machine Shield. If you’re interested in trying it yourself, you can learn all about the finer points of how to use FR4 for enclosures.

Filed under: led hacks, Tech Hacks