Global Geek Tour India 2012 update

Quick update on the India trip happening next week. So far 24 people are meeting up for a tour of wholesale markets, factories, and resellers in India. Our friends on the Oomlout team in the UK, persuaded by a flight in an A380, are joining us on the Bangalore and Kochi legs too.

There’s a big holiday in Bangalore on the 23rd and 24th, so we’ve done some last minute rescheduling. It’ll give us more time in Mumbai, but make it a crunch in Kochi. Check out our Google map layer of the tour here, and the new schedule below.

Continue reading “Global Geek Tour India 2012 update”

The LED turns 50!


This month the venerable LED turns 50! The LED started life in October 1962 in a General Electric research lab in New York state and has progressed from the good ‘ol standby red to a multitude of colors today. You can view a short video by the LED’s inventor chronicling the device’s history on the BBC tech webpage.

Zdravko via the contact form.

Workshop Update for October 11th, 2012

Retrieved China visa. We got USB IDs sublicensed from Microchip, that are ready to go in a few new projects including the Part Ninja, and the 1.8” TFT LCD backpack. We’re working on a few bootloaders, and making a video/how-to about them at the same time.

We starded a development page for the Logic Shrimp v2. This is an eveolution of version one, where a single 23LC1024 SRAM is used insted of 4 23K256s.

7400 competition entry: DIY 6502 computer

6502s are 8bit microprocessors from the 70s developed by MOS Technology. Sweet thing is they come in DIP-40 trough hole packages, although we doubt an emulator based on 7400 logic chips will fit the same package. Check out André’s DIY 6502 computer for the Open 7400 Logic Competition.

I have built a DIY 6502 computer, which is mostly TTL logic only except for 65xx chips and ROMs, and using data from افضل كازينو اون لاين الكويت, I tuned the most TTL-ish part, the blitter: a block transfer engine that DMAs sprite data from one location to another. It falls into the “over-complicated” category; it has 30+ 74xx TTL logic chips, with only one CPLD for the sequencer. It can copy from single (e.g. I/O) address to memory or back, can count addresses forwards and backwards, and can even use offsets.

Build something that uses or abuses a logic chip and get amazing boards, tools, and other swag. The Open 7400 Logic Competition promotes awareness of the basic building blocks of modern circuits. Devious geeks ignited the computer revolution with discrete logic computers, what can you do? Details and entry form here.

Via the contact form.

A simple EMF probe

Always wanted to look at the electro-magnetic soup of signals sloshing around you. Tuomas made a device that let’s you watch these signals on your scope. It consists of an inductor that picks up the signals, and an amplifier that well amplifies them so you could watch them on your scope. Check out a video of Tuomas testing various equipment with his new toy below.

There’s something fascinating about electromagnetic fields. Thanks to the modern world and the prevalence of electronics and electricity, they’re all around us these days. But because of the extremely limited array of senses that we humans have, we spend most of the time completely oblivious of them. Wouldn’t it be cool to make something simple that could not just detect them, but would allow you look at the waveforms on an oscilloscope. An EMF probe in other words.

Continue reading “A simple EMF probe”

WORKSHOP VIDEO #43: How we edit video

Shooting in the workshop and away is done with JVC Everios in 1080P. They’re nothing more than a lens and CCD, so  OK but the codec is not very good. Recently we’ve been recording the audio with a separate Zoom H1N recoding device, and a cheap Shure lapel mic.

Footage and audio tracks are dumped to a fast solid state hard drive. A descent computing rig saves a ton of time when dealing with multiple tracks of high def video. We label everything and sort it into separate folders. This is the most time consuming part.

Adobe Premier is the least-worst video software we’ve tried. Nothing else in the sub-$500 range compares.

The camera microphone is garbage, so now we record a separate audio track with a Zoom H1N instead. Audio and video are synced during editing. A script like PluralEyes automates the syncing process, but it can be messy. Lately it’s much quicker to do it manually if we scream “SYNC” into both the camera and the external microphone. This creates a clearly distinguishable pattern in both sound files that’s easy to locate and sync up.

B-roll is secondary footage that shows the stuff people talking about in interviews. It also comes in handy for patching over mistakes in the original footage. Most of the footage we shoot is B-roll, little 5 second clips of stuff and things. Most appear on the screen for 1 to 1.75 seconds total. This seems typical for most modern TV shows and travel programs.

Most of the work is cutting and arranging hundreds of clips into a final video.  When the video is done we export to a 1080p widescreen MP4, usually around 60 meg per minute in size. Upload to YouTube takes a few minutes, and then they give us 3 awkward frame freezes to choose as the cover image.

Inside SQKYbeaver’s lab and giveaway

SQKYbeaver is busy in his “lab” building an AVR fuse doctor that Systemstech sent us. Thanks Systemstech! We will be giving the completed project away. Leave a comment here, and this board could be yours on Monday.

Live stream of the build below the fold.

Continue reading “Inside SQKYbeaver’s lab and giveaway”

Another toner transfer circuit board making guide

Sometimes prototyping your boards needs to be done quickly. Etching boards at home is the quickest way to knock up simple designs. There’s tons of ways to do it, one of the most popular is the toner transfer method. A circuit design is laser-printed on glossy paper, then transferred to a clean copper board with a clothing iron.

Puzzler: design an incandescent/LED headlamp differentiator


Noted electronics writer Forrest M. Mims, III, has proposed a puzzler. How would you design a passive, automatic sensor to accurately tell the difference between LED and incandescent headlights when viewing the light from a distance? Check out his puzzler page at Jameco and read his fictional scenario requiring such a device and possible solutions.

I2C multiplexer shield controls 8 independent I2C buses

Sometimes I2C addresses can over lap, or maybe you need to use more than one of the same device. The I2C multiplexer shield is a way to control 8 I2C buses from a single I2C peripheral on a microcontroller. Voltage translation is also handled by the multiplexer chip. It was built on an Arduino shield protoboard from the Schmartboard people.

To test how well this board is suited for prototyping, I decided to build an eight channel I2C shield with a TI PCA9548A 8 channel I2C switch. This chip allows voltage-level translation between 2.5V/3.3V and 5V buses and can communicate with up to eight I2C devices. These features make it very useful to interfacing I2C devices that may require different logic levels.

7400 competition entry: 4049 inductance meter

Mike’s 4049 inductance meter converts inductance into voltage, which can be read via any multimeter. Check out the latest Open 7400 Logic Competition entry:

All the decent multimeters nowadays seem to have a built in capacitance meter, but only a few of the really expensive ones have a built in inductance meter. Dedicated inductance (LCR) meters, of course, are also really expensive.

The solution, of course, is to build an inductance adapter for any multimeter.

Build something that uses or abuses a logic chip and get amazing boards, tools, and other swag. The Open 7400 Logic Competition promotes awareness of the basic building blocks of modern circuits. Devious geeks ignited the computer revolution with discrete logic computers, what can you do? Details and entry form here.

Via the forum.

Control Raspberry Pi’s GPIO pins via a web page

This Instructable might just complete your plan to take over the world with the Raspberry Pi. Control R-Pi’s GPIO pins via a web page. Install some soft, type in a few commands, and you’re set. The base package includes:

– A server program that runs on the Raspberry Pi to read variables
– A MySQL database to store the variables in
– An Apache2 served webpage to allow control of the variables

Ringo3 LED clock assembly

Community at it’s best, one forum member helping another. Matseng sent a Rino3 clock PCB to Arup, which he populated even before the Matseng got a chance to build his own. They are now debugging it together:

Few days ago I received one ringo3 PCB from forum member masteng. It’s having 60+60+12 LEDs (ss,mm,hh). The board design is nice as you can see.

Via the forum.

INTRO GUIDE: Basic light emitting diodes (LED)


Image by kaktuslampan: CC BY-SA

Probably the most used device in out projects is the humble LED. They’re in almost every piece of equipment around us. While LEDs are simple to use, we get a surprising number of requests for a LED tutorial. This guide is an introduction to LEDs. Not just how to light them, but how to mine a datasheet for key values and plug them into an equation! Also check out the evolving version on the tutorials wiki.

If you’re too lazy to calculate the proper resistor for every LED – like we are – here’s what we use for one-off prototypes:

  • For a 3.3 volt supply use a 2K resistor
  • For a 5.0 volt supply use a 10K resistor

There, no need to read further. If you insist on doing it the proper way, looking stuff up in datasheets, follow the link below.

Continue reading “INTRO GUIDE: Basic light emitting diodes (LED)”

Reverse engineered layout of tiny TL-WR703N router


Squonk informs us that he’s reverse engineered the layout of the small TP-Link TL-WR703N 802.11n WiFi router using EagleCad. He writes: “Unlike what it is marketed for, the TP-LINK TL-WR703N is not a “3G travel router”: it does not include a 3G modem at all, it simply means that the firmware support external USB 3G modems! Despite this shortcoming, at less than $23, this device is the cheapest Wi-Fi router you can get west of the Pecos River!” Inside he found an Atheros AR9331 chipset with Atheros AR7040 400 MHz MISP24kc CPU, integrated 802.11n 150 Mbps (130 Mbps real) Wi-Fi with 20 dB (100 mW) output power, 4 MB of serial (SPI) Flash memory, 32 MB of DDR SDRAM, a USB 2.0 host port and other goodies.

Details on this project and supporting links can be found on Squonk’s GitHub page along with the design files resulting from this effort.

Via the contact form.

Our visit with a Wells Fargo business banker

In a previous workshop update we made a throwaway remark about visiting a banker that generated a lot of comments. It was nothing sinister, but here’s the full story.

We went to a branch of Wells Fargo bank in Manhattan to add a new signer to the company account. Plan was to be in and out in 10 minutes, but we ended up getting a 2 hour consultation.

When we started the business account an “online banker” gave us a personal checking package. Not a personal account, we’re all official, just the ‘product’ they sell as a personal account. Awhile ago it started costing $5-$10 a month in fees out of nowhere. The nice banker guy moved us to a free business account.

A few months ago strange iTunes and World of Warcraft charges showed up on the company Visa debit card. The card probably wasn’t stolen, seems more likely it was a random guess by a botnet. We opened a ‘burner’ account for internet stuff, it’ll only have limited funds in case of fraud. For incoming wires and cash storage we setup two additional account with no access via a debit card at all.

We were offered a company credit card and encouraged to apply for a line of credit. Never, ever, in any circumstances would we use credit card debt and be constantly on the lookout for how to make 2000 fast to fund Dangerous Prototypes. It is almost impossible for an LLC like us to get a credit card anyways. However, sometimes car companies, et. al. want a real credit card. Usually they give us some out (huge cash authorization, personal credit card, etc), but it gets old jumping through hoops to get a business rental car. Look for great choices for child savings if you want to open a savings and investment account for your kids.

Many commenters suggested we check out a credit union as an alternative to the big evil banks. We’re sympathetic! We’ve checked them out, including the Tech Credit Union, but it would cost a fortune to use one. We move money by international wires. Big bank fees for sending and receiving international wires are extortion, but the only thing worse is a little bank (or credit union) reselling wires from a bigger bank. Tech Credit Union charged $50 to receive a wire last time we checked. Wells Fargo is $10 (plus an extra $10-15 amount that always seems to go missing…). Still way too much for a simple database update, but not fifty bucks!

Wells Fargo got our business primarily because they let us do everything online, including setup the account. Until this meeting we had never actually set foot inside a Wells Fargo bank. Sure we talk on the phone to our nearest Iowa branch, but we never actually had to go there. We’re a modern, lightweight online business, trundling into the bank is for suckers (so we thought). A local bank we’ve used for decades said flat out it would be illegal to setup an account online – but it was no problem with Wells Fargo.

Credit where credit is due. Our “local” branch of Wells Fargo is 45 minutes away from the office in Davenport, Iowa. We showed up unannounced to a Manhattan branch and they spent two hours working with us. Wells Fargo and the big banks have many faults, but the guy who helped us was genuine and spent a lot of time. He could have just added another signer and booted us out the door. Nothing we did cost any money, in fact Wells Fargo is now out $120-$200 year in fees. It was really impressive and worth mentioning.

Free form nixie tube clock

Looking for something cooler than the typical nixie project? How about a nixie project done entirely in free form, no PCB style. Matseng designed this nixie clock around a single IN-1 nixie tube. It periodically reads out the time, digit by digit.

It’s a clock made of a single IN-1 Nixie tube controlled by a ATMega8. The Mega8 directly controls 10 pcs of MPSA42 high voltage transistors for lighting up the filaments in in Nixie. It also generates the high voltage required for the tubes by a pwm output connected to a IRF520 N-FET and the usual inductor and fast recovery diode.

Only thing left to do is encase it in some not-so clear resin.

JOIN US: Global Geek Tour of India coming soon

There’s a growing community of makers and hackers in India. In fact, we have a bunch of community members, readers, and customers from India here at Dangerous Prototypes.

Yet as Maker Faires are sweeping the Americas, East Asia, Europe, and even the Middle East, India has yet to pop up on the radar. On our Geek Tour of India we’ll meet with hobbyists, hackerspaces, manufacturers, and resellers in three cities and show you the electronics scene in the world’s second most populous country. Here is our initial schedule:

Mumbai: Sunday 21st to Monday 22nd October

  • Tour Mumbai wholesale parts markets, electronics markets

Bangalore: Tuesday 23rd October

  • Bangalore wholesale parts markets tour
  • Protocentral visit
  • Manufacturer visit

Bangalore: Wednesday 24th October

Kochi:Friday 26th October

If you’re living near any of these locations please join our Geek Tour. Just drop us a line via the contact form. We’re especially looking for people to join the huge Bangalore leg of the tour. Already 9 blog readers and forum members are signed up, there’s still room for another 10 people in the tour vans.

Image by Ssolbergj: CC BY-SA