The dreamers of Shenzhen’s Maker’s revolution

Another great Shenzhen-Geek tour video from Metalworks:  Maker Faire Shenzhen Trip  Daylon Soh writes:

When the Metalworks team was there in April, we were part of a group of aspiring hardware entrepreneurs and enthusiasts from North America and Europe. Most were looking to bring their hardware product ideas to fruition and were looking for ways to manufacture it cheaply in the city. Some of them would bring their product prototypes back home and raise money on crowd-funding platforms like Kickstarter to get enough pre-sales volume to qualify for cheaper per unit costs. But all of them stumbled with language and cultural differences as we soon learn that everything in the city has a lao wai price and a local Chinese price. 老外 (Lao Wai), is what foreigners of European descent would be called in China, its literal translation would be “old outsider”.


Mini MAME cabinet

in DIY by DP | 2 comments


Greg Kennedy shows you how to make a DIY MAME cabinet project:

 I started this project by taking stock of my components.  Like any good hacker, I have a stack of spare PCs and monitors for occasions like this.  I selected a set that was particularly hard to repurpose, due to its crappy CPU, use of expensive RDRAM, and then the monitor is a 13″ CRT.  These specs would run a vertical cabinet with 4-way joystick nicely.  The “modern” solution is to use some single board computer (say, Raspberry Pi) and an LCD.  I’d rather not send e-waste off to the landfill, plus I’d have to pay for something I already have on hand!

Via Hacked Gadgets.

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Go analog with a resistance-based calculator

in DIY by DP | 2 comments


tanishqjain340 wrote this instructable detailing the build of his analog calculator project:

Do simple calculations with your math box.
The next time you need to crunch a couple of numbers, resist the urge to grab a digital calculator. Instead, round up some variable resistors, also known as potentiometers, and wire them into an analog mathematics rig. By twisting the potentiometers’ knobs and measuring the resulting voltage or resistance with a digital multimeter, you can perform simple multiplication and addition without a microprocessor in sight.

Posted in DIY | Tagged , , | 2 Comments

Electromagnetic Field camp August 29-31, 2014

The 2014 Electromagnetic Field camp is set for August 29-31, 2014.
This annual gathering will be held in Bletchley, UK, and feature a camping festival with a power grid and high-speed internet access; a temporary village of geeks, crafters, and technology enthusiasts that’s lit up by night, and buzzing with activity during the day. Previous events included talks about everything from genetic modification to electronics, blacksmithing to high-energy physics, reverse engineering to lock picking, computer security to crocheting, and quadcopters to brewing.

This year’s conference badge is known as TiLDA MKe and will keep attendees informed of the latest schedule displayed on the badge using automatic updates from a network of radio base stations across the camp site. “At its heart the badge is an Arduino Due compatible 32bit ARM Cortex M3. A rechargeable battery will keep it running for days, and you can charge it over USB when the juice runs out. We added a 128×64 pixel LCD screen, two RGB LEDs, a radio transceiver, joystick, accelerometer, gyroscope, speaker, infrared, and all sorts of other fun parts. It’s compatible with Arduino shields and has dedicated connectors for electronic textiles.”

Tickets are still available online.

Via the contact form.

Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 67 comments


We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading →

Posted in Free PCBs | Tagged | 67 Comments

App note: Overcoming disorientation – Practical ways to assemble MEMS inertial sensors

in app notes by DP | 0 comments


An app note from Maxim,  Overcoming disorientation: Practical ways to assemble MEMS inertial sensors

Component placement and mounting conditions can adversely affect MEMS inertial sensor performance. This application note contains practical considerations for enhancing sensor system operation where the “real-world” environment presents undesirable locomotive signals and system resonances. Topics include placement considerations on the PCB, external motion sources on the PCB (PCB resonance), and assembly mounting considerations.

A similar version of this article appears on EDN, June 4, 2014.

SITE: comments fixed for real, new server coming

in site by Ian | 5 comments


Finally, a real fix for the commenting bug that crops up from time to time. Recently, as well as a year and a half ago, WordPress comments would timeout or give NGINX 504 gateway errors. There were two issues, both related to over zealous security settings:

  • Modsecurity was treating the comment submission, by some versions of WorPress, as a SQL injection attack
  • NGINX security settings were also treating comments as an attack

In both cases security was high, but the server had never been properly tuned for real world situations. We cranked down the security and things seem to be speedy again. Glad to have this fixed because we didn’t want to take the same problem to a new server.

In the coming weeks we will migrate to a new server. After much though and deliberation, we’ve decided to stick with our current host and data center in Germany run by Hetzner.


  • Great prices on great hardware
  • 100% green energy and CO2 neutral
  • Germany’s high level of privacy protection laws
  • Big uplinks to major European internet exchanges
  • We’re used to them


  • An extra hop to US internet exchanges
  • An extra two hops to Asian internet exchanges

It was super tempting to go with a data center in Los Angeles. US readers would get things a tiny bit faster, and it would be a bit faster for people in Asia. That’s especially important when we blog and work from China. China connects to Germany through Los Angeles, then New York, then Amsterdam, then onwards to Germany.

Servers suck power and cooling though. Only a jerk would put a server somewhere drought plagued with energy shortages. For now we stick with Hetzner. Our next box will be huge:

  • Intel Xeon E3-1270 v3 Quadcore Haswell
  • Hard Drive 2 x 2 TB SATA 6 Gb/s 7200 rpm Enterprise Class
  • Connection 1 Gbit/s-Port
  • Guaranteed Bandwidth 200 Mbit/s
  • Backup Space 100 GB
  • Inclusive Traffic 20 TB

Please offer any pros and cons of this setup if you have them.

Our current server doesn’t include backup space so we pay for Jungle Disk (IMHO junk and impossible to actually use…) as well as two different FTP backups for hourly database dumps. We’ll probably dump all but a single FTP backup and use the included off-site backup space, saving nearly a hundred bucks a month.

We also use an Amazon Web Service instance for MUNIN, a server monitoring setup. MUNIN did exactly nothing to help spot the failing drive issues with the current server, not that anyone bothers to monitor it anyways. This should be trashed or moved to a dirt cheap Digital Ocean droplet instead of the really expensive AWS instance.

Most sites, including those run by people we love and respect, invite to their websites alleged NSA collaborators, US government spy facilitators, and general data hogs to monitor your every move for profit, data mining, advertising, etc. As always, we never knowingly run any social media malware that allows Facebook, Twitter, Google, et. al. to track you at Dangerous Prototypes.

Even sites that avoid social malware frequently use Google Analytics for site statistics. We refuse to do that. We host our own stats package called Piwik. It’s open source, compliant with stringent German privacy laws, and only we know what happens on our site. If big brother cares to spy on you they can tap the cable, however we will do our best to keep big business from data mining you.

App note: Tips and tricks to optimize your C code for 8-bit AVR microcontrollers

in app notes by DP | 5 comments


An application note (PDF!) on code optimization in AVR microcontrollers from Atmel :

• Atmel® AVR® core and Atmel AVR GCC introduction
• Tips and tricks to reduce code size
• Tips and tricks to reduce execution time
• Examples application

AVR core is an advanced RISC architecture tuned for C code. It ensures the development of good products with more features at less cost.
When talking about optimization, we usually refer to two aspects: code size and code speed. Nowadays, C compilers have different optimization options to help developers get an efficient code on either size or speed.

Posted in app notes | Tagged | 5 Comments

ytimer: Visual feedback timer

in project logs by DP | 4 comments


Here’s an update on Aon’s boards from DirtyPCBs we covered earlier, a visual feedback timer project:

Here’s what became of one of the boards after a bit of soldering and programming: a countdown timer with visual indication of when the time’s up instead of an alarm (there’s a place for a piezo buzzer on the board tho, but I don’t have any at the moment). My wife wanted one so i made one :)

Counting down…
Blinking! The displays are Kingbright SA52-11SURKWA’s which were the brightest I could find. Sadly their availability isn’t too great.

Via the project log forum.


Posted in project logs | Tagged , | 4 Comments

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 8 comments


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.

Don’t forget there’s free PCBs three times every week:

Continue reading →

Posted in Free PCBs | Tagged | 8 Comments

Week in (p)review August 15, 2014

in week in review by DP | 0 comments


Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

  • Free PCBs via Facebook on Friday
  • App notes on the weekend
  • Free PCB Sunday
  • Free PCBs via Twitter on Tuesday
  • Weekly roundup and preview every Friday

Got something dirty in the post today from DirtyPCBs

in project logs by DP | 0 comments


Aon posted pictures of the boards he ordered from DirtyPCBs in the project log forum:

Just received these boards I ordered from two weeks ago. Came with complimentary tweezers and all :D
Also received a USB microscope today, so here’s a close-up of a SOT-363 package and some 6 mil traces. The silkscreen seems to be just a hint offset but certainly good enough.
Overall I’m very satisfied with the boards and the delivery time. Guess I’ll start putting components on one now to see how badly I’ve messed up the layout :)

Via the forum.

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PIR sensor

in security, sensors by DP | 0 comments


An automatic PIR sensor project by Rajkumar Sharma of Electronics Lab:

Project is based on Holtek’s IC HT7610A, which is a CMOS LSI chip designed for use in automatic PIR lamp, flash or buzzer control. It can operate in 3-wire configuration for relay applications. In our project we have used relay instead of Traic to connect any kind of load in output, HT7610B IC is suitable for traic and HT7610A for Relay application. The chip is equipped with operational amplifiers, a comparator, timer, a zero crossing detector, control circuit, a voltage regulator, a system oscillator, and an output timing oscillator.
Its PIR sensor detects infrared power variations induced by the motion of a human body and transforms it to a voltage variation. If the PIR output voltage variation conforms to the criteria (refer to the functional description), the lamp is turned on with an adjustable duration. The circuit doesn’t required step down transformer and can work directly by applying 110V AC or 220V AC (Capacitor C7 needs to change for 220V AC (0.33uF/275V) and 110V AC (0.68uF/275V)

Reverse engineering a NAND flash device management algorithm

in reversed by DP | 2 comments


Joshua Wise writes:

The following is a description of how I went about reverse-engineering the on-flash format, and of the conclusions that I came to. My efforts over the course of about a month and a half of solid work – and a “long tail” of another five months or so – resulted in a full recovery of all pictures and videos that were stored on the SD card.

Via Electronics Lab.

Wireless ADC to relay example

in wireless by DP | 0 comments


Ondřej Karas of DoItWireless writes:

Sometimes, you need to measure analog signal and then switch something on or off according to the result. This short example shows, how to do it. Everything you need is DDC-SE-01 module as a sensor module and DDC-RE-01 as relay module. Of course you need DK-EVAL-04 or CK-USB-04 for both of them as a master module.
This example originates from IQRF contest Example 12. It was simplified and changed for TR-52D module.


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Aperture scripting: Panelize and manipulate Gerber files

in library, PCBs by DP | 1 comment



Doub has announced the release of the Aperture scripting, a set of Lua libraries to manipulate PCB data files. He writes:

At the core of my Gerber Viewer (that you’ve made quite popular, thank you all), there’s always been a set of Lua libraries to load the Gerber and Excellon files, and I’ve privately used them to also manipulate these files and generate panels among other things. I’ve finally took some time to clean it up, polish the feature set, fix many bugs, and document the whole thing, and it’s now available for all to use.

Via the forum.

Posted in library, PCBs | Tagged , | 1 Comment

DIY binary wrist watch

in DIY, PIC by DP | 0 comments


Elia wrote an article detailing his binary wrist watch project:

I have just finished my binary wrist watch project (well, the new revision anyway). I was surprised at how small I was able to make it compared to last time.
I chose to go with the “super-yellow” color LEDs as they fit the purple OSHpark PCB very nicely. The biggest challenge was actually making a good looking wrist band for the watch. I originally intended to use a design like this but it turned out that due to lack of enough para cord I had left, I went with a simpler design that I had done once before.

Cheap laser cutter arrives pretty busted up

in #liveupdates, tools by Ian | 13 comments


Like many others we have succumbed to the urge for a cheap laser cutter. What started as a $200 purchase quickly doubled, but that’s still a fraction of the cost of an expensive one. Why do we what it? That’s a not very well hit secret.


The ubiquitous blue Chinese freight truck drops the crate on the corner in the rain. We use our huaqiangbei style cart, courtesy of Oomlout, to wheel it home. It took 7 days from ordering on Taobao to delivery.


The laser cutter in the crate.


So everyone has issues with these cheap cutters. Our biggest issue is two capacitors from the power supply rolling around in the crate. These didn’t just pop off, the leads are seriously messed up. There’s no way this went into the box without the packer noticing. They weren’t even in the electronics compartment, they had been tossed into the side of the crate with the accessories. Not sure we are daring enough to fix this here. Aftersales service will call tomorrow.


A lead from the psu has snapped. It obvious why, the cable isn’t long enough for the compartment lid to open at all. Any force at all with break the entire assembly. Easy fix though.


A random wire out the side and tied. Assume this is an unused lead from the optional water pump detection and kill switch.


A laser sight was supposed to be included but was completely missing
Assume they will send it and we can install it.


The 50w laser tube is intact though. There is an extra broken zip tie of unknown origin.


The optional honeycomb insert doesn’t remotely fit the cutter bed. Not sure how it is supposed to be used at all.

Dissapointed? Absolutely not. At least not yet. We researched before making the purchase and expected some issues and bringup issues. Comments on taobao also related issues, but the service team supposedly deals with them quite well. The snapped caps are a bit alarming, but we’re five minutes from the biggest electronics market in the world and a qualified repair person will have it fixed in a few minutes.

These are first impressions from the WordPress mobile app while waiting for ribs. Full review coming once we have a chance to fix it up and play a bit. Oh yeah, and cut some free…

Posted in #liveupdates, tools | Tagged | 13 Comments