App note: LED lighting and supercapacitors

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An app note (PDF) from KEMET on coupling two high lifetime devices: LEDs and Supercapacitors.

Light emitting diodes, or LEDs, have come to prominence in recent years in conventional lighting applications including flash lights, street lamps, traffic lights and emergency lighting. Their advantages over incandescent and compact fluorescent light sources include greater robustness, higher energy efficiency and a longer lifetime. Due to the constantly falling prices of LEDs, they are also now becoming more economical in the long term than traditional light sources.
Supercapacitors are high lifetime, high power devices that store relatively little energy compared to a battery. The low power requirements of LEDs means that a reasonably sized supercapacitor power source can still provide several hours of lighting on a single charge, while the high lifetime and low-temperature performance advantage over batteries is maintained. The emergence of 3.0 V supercapacitor cells as well as hybrids only strengthens the case for their use in LED applications due to the higher amount of energy stored in these new supercapacitor types. Supercapacitors are also free of lead, mercury, and cadmium, which eases any environmental concerns that may arise over the course of their long term use and eventual disposal/recycling.

App note: Bluetooth smart communication using Microchip RN4020 module and 16-bit PIC microcontroller

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An app note from Microchip, Bluetooth smart communication using Microchip RN4020 module and 16-bit PIC microcontroller (PDF!):

This application note provides the following:
• Framework for any of the user application platform
using RN4020 module and PIC24FJ series
of microcontrollers.
• Specifically an interface of RN4020 module with
PIC24FJ128GA010 microcontroller.
• Start up or reference code to command RN4020
module through PIC® microcontroller.
• Initial procedures or techniques for interfacing a
PIC microcontroller and BLE module.

Note: This application note is not intended to
provide a complete understanding of the
Bluetooth technology principles or using
the commands related to the RN4020
module.

Free PCB coupon via Facebook to 2 random commenters

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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.  The coupon code usually go to Facebook ‘Other’ Messages Folder .  More PCBs via Twitter on Tuesday and the blog every Sunday.

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

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Getting started with an I2C LCD using a Bus Pirate

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Inderpreet over at Embedded Code writes:

I got one of these (The LCD!) LCDs from the budget and the motive is to use them to display air quality. Low and behold I got them and these things are tiny… I mean more than I thought. BUT they should get the job done. This post is a little one where I try and get it to work and experiment with I2C. Lets go!

Get an assembled Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Teardown and repair of an Agilent E4433B ESG-D synthesized signal generator

Teardown and repair of an Agilent E4433B ESG-D synthesized signal generator:

In this episode Shahriar repairs an Agilent E4433B ESG-D Synthesized Signal Generator. This 4GHz unit shows the “UNLEVEL” error for all frequencies and at all output power levels. After a close look at the system block diagram the fault is traced to the main Output RF board.

HC-05 Bluetooth link with zero code

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Phillipe Cantin writes:

So you want to two HC-05 modules to automatically connect together, as soon as they’re powered up and with zero code? Well this is your lucky day since this can be done using the AT+BIND command.
Let’s do this thing!
For this, you will need:
1 Arduino (I’m using UNO)
2 HC-05 modules
1 breadboard
Wires
Arduino IDE (I’m using version 1.0.5-r2)

PCB Christmas Tree Ornaments

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Our office Christmas Tree is decorated with PCBs this year. Bitmap images of classic Christmas iconography were imported into Eagle for the board outlines. Decoration was supposed to be exposed silver areas but something went wrong. Instead, we just traced over the masked copper with markers. Should you like your own next year these will all be available in our SVN as soon as we’re done unwrapping gifts.

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OneRNG – an open source entropy generator

Moonbase Otago is pleased to announce its Kickstarter campaign for OneRNG – an open source hardware entropy generator:

OneRNG is a USB key in the same form factor as a USB flash drive, it’s an entropy generator, it makes random bitstreams suitable for feeding to your computer’s encryption systems to make better and faster keys to make interception of your communications more difficult. It has two entropy sources, an avalanche diode and an RF noise source, either or both can be used

OneRNG is also open hardware, that means all of the design, both hardware and software, is Open Source – you can inspect the hardware and software to make sure there is nothing hidden that stops it from functioning as promised. It also means that you can inspect a unit after shipping to make sure it has not been tampered with, both by lifting its lid to look at the components, and by inspecting the embedded firmware both to make sure that it contains what you think it does and also that it is cryptographically signed with a valid key.
Because you don’t truly own your own hardware unless you can reprogram it we’re also offering device programmers for those who want to take the existing software and make it better or their own.

Arduino heart rate sensor

An Arduino pulse sensor project from Bajdi:

I found a little heart rate sensor @ ICstation. It is a clone of the open hardware pulse sensor. The sensor is well documented, and it comes with Arduino and Processing example code.
To try it out I connected the sensor to an ATmega328 running at 3.3V and loaded the example Arduino code. I could now see my heart beat on the Arduino serial monitor :)
I then connected a 2.2″ TFT display to the Arduino and tried to figure out how to display the sensor output on it. Sounds simple but unfortunately it isn’t. Updating the full screen (320×240 pixels) is really slow. So I needed some smarter code to update only the pixels that needed to change. I happened to stumble on Matthew McMillans blog, he wrote some smart code to use a similar display as a speedometer. So I borrowed some of his code and mixed it with the example code of the pulse sensor. You can see the result in the above video.

Code is available on Bajdi’s site.

#FreePCB via Twitter to 2 random RTs

KHOS-2-3-4-5-6P Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Teardown of Kentli PH5 1.5 V Li-Ion AA battery

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Jason over at Rip It Apart did a teardown of a Kentli PH5 1.5 V Li-Ion AA battery:

The PCB that holds the 1.5 volt regulator is inside the end cap, with the rest made up of the Li-ion cell itself. Curiously enough, the cell inside is labeled “PE13430 14F16 2.66wh” which is interesting in more than one way. First of all, the rated energy content of the cell is less than what’s on the outside label (2.66 watt-hours versus 2.8), and the cell inside is actually a Li-ion polymer (sometimes called a “Li-Po” cell) type; I was expecting a standard cylindrical cell inside. Unfortunately, my Google-fu was unable to pull up any data on the cell. I might attempt to do a chemistry identification cycle on the cell and see if TI’s battery database can bring something up.

More details on Jason’s blog.

LittleBits Hue lighting controller

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Jeremy Blum has written an article about his latest project the LittleBits Hue lighting controller:

The LittleBits Hue Controller is an easy-to-setup, wall-mountable, physical controller for your Philips Hue lightbulbs. The controller makes it easy to turn the lights on/off, change their brightness, and cycle through preset colors. This is a great project for people who hate having to pull their phone out every time they want to adjust their lights.

Complete build details can be found on Jeremy Blum’s site with the code hosted on GitHub.

PWM Based LED Driver

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A followup to the constant current driver for a high power LED post, Elmars writes:

If anybody is interesed, I have posed a follow up to this original post with a simple PWM LED driver, adding an 씨벳 ATtiny85 mCU. The post includes schematic, board layout and code for the ATtiny85. I hav tested the circuit up to 22 volts without a current limiting resistor. The FET only needs a small heat sink. Efficiency can be further improved by replacing the LM358 with an RC/LM741. The LM741 has a much sharper rise and fall time than the LM358 when run at 2KHz, resulting in the FET spending less time as a resistor. (during the slow ramp/fall the FET acts as a resistor, generating heat)

Via the comments.

Inside the Intel 1405: die photos of a shift register memory from 1970

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Ken writes:

In the Datapoint 2200, each memory board had 32 shift registers, providing 2K of storage. The processor board used a counter to keep track of the shift register position, and would stop processing until the right bits were available. (Kind of like a cache miss in modern processors.)
I got a display board from a Datapoint 2200, which uses Intel 1405 shift registers for the display storage. This board uses 14 shift registers and holds 896 bytes. Shift-register memory was convenient for a video display board, since the circuitry needed to access each character in sequence to display it.

Details can be found on Ken Shirriff’s blog.

Free PCB Sunday: Pick your PCB

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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:

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App note: Design considerations for single-sided sensing applications of reflective assemblies

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App note from TT Electronics on reflective assemblies and the surfaces they need to effectively detect/sense.

A reflective sensor provides a major mounting advantage to the designer because only one side of a sensing surface is required. However, there are a number of design variables that need to be considered to assure detection of the object or target. They include the type or size of the reflective surface, the distance to the reflective surface, variation of surface reflectivity, sensor variation and contrast ratio.