App note: Technical guide to surface mount resistors

Here is a technical guide to surface mount resistors from Panasonic. It covers the theory behind various resistor materials and the manufacturing processes. Tables illustrate specifications for different types of resistors, and explain the failure mechanisms for them.

Fixed resistors are principal electronic components composed electronic circuit. They are developed with demands of various electronic circuits and used. This technical guide is summarized the application technique about surface mount resistors used for electric machine and tools, especially, which need high density mount in these fixed resistors.

Chronos hacking update


JP Norair has been hacking away with the TI 433 MHz Chronos.

My project is OpenTag, which is a 433 MHz centric IoT/M2M stack. It’s 433-centric because it implements DASH7 and because it makes design assumptions that multihop is not of great importance (at 433 MHz, it certainly isn’t). You can check the wiki, which is admittedly incomplete, but it’s a good starting point.

JP reports that some of his friends at Wizzilab are doing great things with the Chronos 433 kit. They’ve even put together a free IDE with Code::Blocks and mspgcc.

Via the comments.

Free PCB Sunday: Pick your PCB

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:

  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs while you wait for the weekend
  • Free PCB Sunday, right here on the blog

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Enhancing ADC resolution by oversampling

Atmel describes how to enhance ADC resolution by oversampling the signal and averaging the extra data. This has a side effect of increasing the signal to noise ratio, and reducing the quantization error.

When the ADC samples a signal, it quantizes the signal in  discrete steps. This introduces some error, often referred to as  quantization error. Normal averaging will only even out signal fluctuations, while Decimation will increase the resolution. In a  4- times-oversampled signal, four adjacent data points are averaged to produce a new data point. Which frequency to oversample the signal with, can be calculated by equation 3-1.

Adding these extra samples and right-shifting the result by a factor n, yields a result with resolution increased by n bits. Averaging four ADC results to get a new ADC result is the same as if the ADC sampled at ¼ of the rate, but also has the effect of averaging the quantization noise, which improves SNR. This will increase the ENOB and reduce the quantization error. With the availability of faster ADCs and with low memory cost, the advantages of oversampling are cost effective and desirable

Free online DSP book

Squonk alerts us to a very interesting online resource. California Technical Publishing has posted a complete copy of The Scientist and Engineer’s Guide to Digital Signal Processing by Steven W. Smith, PhD. This 640 page volume covers all aspects of DSP and is both searchable online and downloadable. The site also includes links to software and code examples from the book.

Though it appears to be the 1997 edition, this is still a valuable resource for beginners wanting to learn about DSP without investing a lot of money.

Via the contact form.

App Note: Comparing digital and mechanical potentiometers

Microchip compares mechanical and digital potentiometers to digital. This app note explains the theory behind both versions, and their advantages and disadvantages.

Mechanical potentiometers have advantages in terms of having a wide variety of values available and tighter specifications such as nominal resistance, tolerance, temperature coefficient, power rating and temperature range specifications. But in many applications the overriding
factors are related to environmental and reliability issues. These characteristics are not necessarily specified by the mechanical potentiometer vendor.

Digital potentiometers go hand in hand with the drive towards digital system control. This type of potentiometer is considerably more robust that its predecessor, the mechanical potentiometer, in terms of environmental exposure issues and longevity with repeated use of the wiper. But beyond the reliability issues, the digital potentiometer offers hands-off programmability. This programmability also allows the user to repeatedly and reliably return to the same wiper position.

Bus Blaster v2.1a free PCB build

Victor built a free Bus Blaster v2.1a PCB. He soldered it up by using a hot plate, or more accurately a frying pan. This had the undesired effect of producing some hard to debug solder bridges on the tiny resistor network packs.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

You can get a Bus Blaster v2 for $34.95.

Hua Qiang Bei District electronics market in Shenzhen, China

Guys over at Seeed wrote about their neighborhood, the Hua Qiang Bei District located in Shenzhen China. This is arguably the largest electronics market in the world. Covering several city blocks populated by ten story buildings all blistering with electronics shops.

This will be our next Global Geek Tour which we’ll be visiting in April. We’ll check out how it compares to the Akihibara in Tokyo, and Cheonggyecheon in Seoul. As with all our Global Geek Tour events expect videos and detailed pics to follow.

Image by Bobbie: CC BY-SA

Via Seeed.

LED produces 2.3x more light energy than electrical energy consumed

MIT physicists developed an LED that emits more light energy than the electrical energy consumed. These LEDs supplement electrical energy with heat from the surrounding environment. Unfortunately this has only been observed at very low power levels.

The researchers chose a light-emitting diode with a small band gap, and applied such small voltages that it acted like a normal resistor. With each halving of the voltage, they reduced the electrical power by a factor of 4, even though the number of electrons, and thus the light power emitted, dropped by only a factor of 2. Decreasing the input power to 30 pW, the team detected nearly 70 pW of emitted light. The extra energy comes from lattice vibrations, so the device should be cooled slightly, as occurs in thermoelectric coolers.

Via: Adafruit

Free Model Foundry: open source CPLD/FPGA simulation models


Here’s a site we found containing open source simulation models for system level verification of CPLD/FPGA devices.

“Founded in 1995, Free Model Foundry (FMF) is dedicated to promoting standard modeling practices within the electrical engineering comunity. In particular, we support the use of VHDL, Verilog, and SystemVerilog modeling languages.

They believe in free, open source distribution of simulation and analysis models of electronic components. It promotes the development, distribution and sharing of functional simulation models (with timing) for board level components and open source behavioral models for proprietary IP.”

Free PCB coupon via Facebook to 2 random commenters


Help Hacker Space Seoul take Iron Hack to Beijing with a vote on Facebook, read more about it in our previous post.

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 a every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Week in (p)review: March 16, 2012

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
  • New 3D model on Monday
  • Free PCBs via Twitter on Tuesday
  • Weekly roundup and preview every Friday

What are you hacking this week?

Vote for Iron Hack on Facebook, send Hacker Space Seoul to Bejing

Help Hacker Space Seoul take Iron Hack to Beijing with a vote on Facebook.

Iron Hack is a workshop organized by Hacker Space Seoul where participants have 2 hours to build something meaningful, or artistically pleasing with a soldering iron. With enough votes on Facebook they score a free trip to Maker Carnival 1 in Beijing, China.

We visited Hacker Space Seoul on our recent Geek Tour of South Korea electronics markets. Please help us say thanks with a vote for their project if you’re on Facebook.

Print nanometer precision 3D objects at high speed

Researchers at the Vienna University of Technology developed a process to speed up high precision 3D printing. A focused laser beam cures resin and develops a hard object just a few hundred nanometers wide.

This method is well known, but what sets this printer apart is the new control mechanisms for the mirrors that focus and position the laser, as well as improvements in the Resin chemistry.

Normal laser/resin 3D printers of this precision have a speed of a few millimeters per second, while theirs has the speed of a few meters per second.

Via Pad&Tablet Forensics.

CORDIC for dummies


Drone writes:

Here is a thread on the Parallax Propeller Forum discussing the downloadable document by forum user “Bean” called “Cordic for Dummies”.

This document attempts to explain how CORDIC works. CORDIC (COordinate Rotation DIgital Computer) is an algorithm used in low level programming or programming languages with limited math support or processors with no hardware multiplier (e.g., microcontrollers and basic CPLD/FPGA devices) to calculate hyperbolic and trignometric functions.

Via the contact form.

GLOBAL GEEK VIDEO #11: Yongsan and Cheonggyechon electronics markets in Seoul, South Korea

This week we take you on a Global Geek Tour of the electronics markets in Seoul, South Korea. Seoul isn’t known for its markets like Tokyo or Shenzhen, but with electronics giants like Samsung based here there’s a huge and thriving scene.

We visit Yongsan, then stop by Hacker Space Seoul before heading into the depths of Cheonggyecheon.

Check out our pictures and reports from earlier in the week.

We’ve got everything you need to take your own Geek Tour. Check out our map of Yongsan and map of the Cheonggyecheon area. There’s also a Google Map layer to print or load on your phone.

Don’t forget our previous Global Geek Tour of Akihabara Electric Town in Tokyo, Japan.

Buy a vintage calculator get 8 Nixie tubes free

Philip scored a vintage Sanyo 4 function calculator in a local thrift store. He opened it up and was pleasantly surprised with 8 Nixie tubes.

You guys wont believe what i just scored from a local thrift store [selling second/third/fourth hand stuff from japan] :)

A good old 4 function calculator from sanyo – and when i opened it up there is a set of nixies!

Via the forum.