#FreePCB via Twitter to 2 random RTs

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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.

Troubleshooting damaged chips

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Steve at Big Mess o’ Wires writes:

The most common failure I’ve seen is something I call “burnout”, and has affected about 4% of the units. After anywhere from one minute to a few hours of working normally, the Floppy Emu stops functioning, and both the 3.3V regulator and the CPLD become hot to the touch. The AVR, SD card, and LCD still seem to operate normally, but floppy emulation or anything else involving the CPLD no longer work. After some experimentation, I discovered that if the CPLD is removed and replaced using a hot air gun, the Floppy Emu can be returned to normal functioning and the problem does not reappear.
Hot chips imply a short circuit somewhere. Measuring the current draw is tricky, because Floppy Emu is normally connected directly to the Macintosh which powers it, and there’s no place to insert an ammeter inline and measure the current. I finally broke down and built a simple bench test rig, where the Floppy Emu is powered from an external power supply and no Macintosh is involved. This only provides a way to measure the current draw of the whole board, and not individual chips, but it’s better than nothing…

DIY Arduino bluetooth programming shield

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Here’s a how-to on making a DIY Arduino Bluetooth programming shield by Joshua Newell:

If you’ve ever wished you could program your Arduino without lugging a USB cable around, wanted to put an Arduino project somewhere out-of-reach but still be able to easily upload changes to it, thought about building a project that interfaces with an Android phone, or contemplated a way to get remote sensor data streamed to your computer — this project is for you.
It uses a common, low-cost Bluetooth module mounted onto a prototyping shield for durable and reliable use. Along with the module is a circuit that allows the Arduino IDE to automatically reset the Arduino when uploading a new sketch. This project also uses the latest version of the Arduino IDE which eliminates the need to hack in modified DLL files to get the serial programming to work.

Via MAKE.

A digital thermometer hygrometer with analog displays

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Kerry Wong writes:

In this post, I will show you yet another thermometer/hygrometer build. But instead of using an LCD or 7 segment display for the output, I decided to go retro, using two “needles” to display the temperature and humidity readings instead.
And to make the project more fun, I did not use analog meters for the output but chose to use two servos instead. The temperature humidity sensor I used is SHT21 from Sensirion, the same sensor I used in my temperature logging project before. In that project, the temperature and humidity readings were sent over the network and displayed on my web server (you can see the current readings in my lab here).

EasyPIC v7 development board review

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Raj of Embedded Lab has posted a detail review of mikroElektronika’s popular EasyPIC v7 development board:

MikroElektronika, a Belgrade, Serbia-based company is well-known for producing quality software and hardware development tools for a wide range of microcontroller families, including PIC, AVR, and ARM processors. Their mikroC Pro for PIC has always been my favorite PIC compiler, and has been extensively used in my PIC tutorials and projects published on this website, for its ease of use and rich set of built-in library routines. Today, I am reviewing MikroElektronika’s EasyPIC v7, which is the latest PIC development board in their line of EasyPIC series. I would like to thank to Newark USA for providing the EasyPIC v7 board for completing this review.

Via the contact form.

BeagleBone Black and MSP430 based Wireless Sensing

Chirag Nagpal created prototype of a Wireless sensing system using MSP430, BeagleBone Black and XBee:

I have developed a Wireless Sensing System using an MSP430 microcontroller based node, powered by 2 AA batteries, relaying data to a BeagleBone Black using XBee. The BeagleBone is then hosting a javascript based webpage graphing these values using processing.js. The webpage served by the BeagleBone black is displayed on my laptop.

Via the contact form.

Experience with the TM240A pick and place

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Chuck of LinearLogiX writes:

We bought the TM240A and found it works pretty good for our needs. A couple items I found was that using the SMD type tant caps on a reel, I had to actually Grind the side to open width so the plastic holder would fit. As you can see in the pictures it would bind and not pull through.

Also we used our 3D printer to make some holders for the front trays that would allow us to use parts in different configurations. In the pictures I’m showing only the 2512 resistor but we have some parts for SOIC8,16, SOT223 etc, this allows us to place multiple different type components And keep them centered in each tray, thus you can mix and match component types and have a centered point for pick up on each component.

Via the contact form.

Continue reading “Experience with the TM240A pick and place”

Cypress PSoC4 chip sale

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Cypress Semiconductor, makers of the popular PSOC4 Pioneer kit, are making their PSOC4 chips available for a limited time for $1.00 each, including free worldwide priority shipping. (Note, this price is for the chip alone, NOT the Pioneer Kit.)

“PSoC4 is a scalable and reconfigurable platform architecturefor a family of mixed-signal programmable embedded system controllers with an ARM Cortex-M0 CPU. It combines programmable and re-configurable analog and digital blocks with flexible automatic routing. The PSoC 4200 product family, based on this platform, is a combination of a microcontroller with digital programmable logic, high-performance analog-to-digital conversion, opamps with Comparator mode, and standard communication and timing peripherals.”

For ordering details visit Cypress Semi.

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Adjustable Electronic Load for Low Voltage DC Applications

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Here’s an old but still good app note from Unitrode (Texas Instruments) on Adjustable Electronics Load.

Testing power supply regulation over a specified output current range is greatly simplified with the use of an adjustable electronic load. Load current can be varied from zero to the full rated value with the twist of a panel mounted potentiometer or by a digital interface. This design note will feature the design of a self biased, constant current adjustable electronic load which is fully operational with input voltages down to 2.5V.

App note: How P-Channel MOSFETs Can Simplify Your Circuit

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An app note from International Rectifier on using P-Channel MOSFETs

P-Channel HEXFET Power MOSFETs offer the designer a new option that can simplify circuitry while optimizing performance and parts count. In principle, nothing can be done with a P-Channel MOSFET that cannot be done with an N-Channel plus some extra gate drive circuitry. The main advantage of a P-Channel device is circuit simplification in medium and low power applications. This app note explains that P-Channel MOSFET has significant higher power losses that discourage its application in higher power circuits.

MIT wins prize for $20 robot

John Tarbox reports that MIT’s CSAIL team has won first place in the categories of hardware and curriculum for a printable, origami-inspired Segway robot, called SEG, at the “Ultra-Affordable Robot” competition sponsored by the African Robotics Network (AFRON) and the IEEE Robotics and Automaton Society. The robot can be built for about $20. Its made of polyester and moves around on two large wheels and can avoid obstacles. The navigation system design is based on the ATTiny24 MCU, a voltage regulator, two servos and a handful of discrete parts.

For details on the design of the MIT SEG, visit the project web page.

Via the contact form.

Infrared Receivers – signal lag and distortion

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The crew from AnalysIR writes:

Many electronics enthusiasts will be familiar with how Infrared receivers demodulate IR signals. In this post we show a visualisation of the time lag and distortion of the signals as they pass through the IR receiver for demodulation and noise filtering. Most DIY projects use the raw timings from the IR receiver to decode individual signals. However, not many will be aware that IR receivers can distort the signal timings by significant amounts. Fortunately, common IR decoders take this into account and compensate for timing distortions introduced by infrared demodulators / receivers.

Via the contact form.

Free PCB coupon via Facebook to 2 random commenters

STICKERSeEvery Friday we giveaway 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:

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Week in (p)review March 28, 2014

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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

SMD March – Tweaks to Ishan Kehribar’s ethernet gateway

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TomKeddie writes:

For our SMD March workshops I chose Ishan Keribar’s Embedded Ethernet Gateway. I added an FT230X and usb port with a Arduino uno style reset on CTS (230X has no DTR but avrdude toggles both). I also used a SOB 5050 template to make cases easy to design. By adding an 8MHz variant to the Arduino board config you can then download sketches like a Arduino – this is a little more accessible than a STK500.  Unfortunately I made two errors on the PCB, they’re fixed by cutting tracks as seen in the photos.

Via the project log forum.

March 29, 2014 is Arduino Day

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March 29, 2014 marks the 10th anniversary of the Arduino and the team has marked the day for a worldwide celebration of Arduino’s first 10 years. “It’s 24 hours full of events – both official and independent, anywhere around the world – where people interested in Arduino can meet, share their experiences, and learn more.”

Events are being planned worldwide, so check out the Arduino Day page for more info or to locate or set up an event near you!

@tymkrs MorePi Me v1 Pi shift register board

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Charles Douvier blogged about his MorePi Me he won in a contest:

I unpacked the board and soldered it all together. Not a lot to say about it because it’s just a board, four DIP sockets/74HC595′s a couple connectors and 3 resistors. I like that they included sockets; I would have added them myself but sockets is a must on hobbyist boards!
whixr also send me some test code … happy day.

So I hooked this up and dropped code into it last week.. I left it to burn in all week.. and checked it out today; no problems. I put the Pi on bench and hooked up my logic analyzer … works as advertised. Look at the screenshot of the output for how whixr code works. I’ll also include a copy.