Here is a reference design from Maxim how to built a circuit that would seamlessly switch to the secondary power supply if the primary fails.

This power-supply sequencer senses a loss of the main supply voltage and, by controlling the two FETs, automatically switches the load to the secondary (backup) supply.

Starting to get busy at the Dangerous  Prototypes booth! For live updates from the Bay Area Maker Faire check out our Twitter feed.

More pictures below

Skot with his digit grid.

MacGyver class: Learn to save the world using nothing but an egg carton and a plastic spoon.

LED Lounge: macetech.com

The Elixerator.  Steampunk-style drink mixer can make 10 different cocktails.

Keep your garden safe….

Robot petting zoo – Makerbot.com

Super Mario lamps (complete with the noise).

Someone call a Doctor!

Pedal-powered concert

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

Are you interested in blogging with us? Drop us a line. This probably won’t be a paid position, but you get a back stage pass, free PCBs, and free projects. US and international bloggers are welcome.

Some stuff:

• Yes, we’ll mail it anywhere in the world!
• Be sure to use a real e-mail in the address field so we can contact you with the coupon.
• Limit one PCB per address per month please.
• Like everything else on this site, PCBs are offered without warranty.
• PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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Accustomed to microwave circuit design which requires miniature dimensions, his project was built on a 35mm by 35mm board. The circuit consists of a standard 8-pin DIL PICAXE (an 08M), a 5-volt SMD regulator, an SMD-style LM386 audio amplifier plus extra SMD components for easy switching and filtering.

You can find all the details on how this project progressed from concept to the finished product shown above, along with the Picaxe code and schematic at VJ4ADC’s website.

For information on the Picaxe line of MCUs, and to download their free programming IDEs for Linux, Mac and Windows, visit the Picaxe website.

Here is a reference design from Atmel designed to demonstrate the Qtouch capabilities of the ATtiny40 microcontroller. Only one pin, and a PCB pad is needed to make a capacitive touch button.

The reference design is to demonstrate the capabilities of the Atmel ATtiny40, which supports QTouch, the latest capacitive touch technology. The technology requires only a single I/O pin per touch channel. The reference design supports two analog output channels using PWM, buzzer, and LEDs indicating touch, and TWI or SPI communication interfaces. It also allows  complete configurability, and supports off-board QTouch  sensors.

In June 2011 the electronics world lost a great man, Jim Williams. He was a analog circuit guru, and a scientist at Linear Technology. Here is a collection of some of the app notes he wrote.

Via the Amp hour.

Here are some pics we took while setting up at the Bay Area Maker Faire. If you are visiting, be sure to say hi at our booth (#2).

For live updates from the Maker Fair check out our Twitter feed.

More photos below the fold.

The PSoCs are interesting here because they mix a CPU (up to Cortex-M3) together with CPLD capabilities together with programmable / reconfigurable analog components (DAC, up-to 20bits ADC, OpAmps, filters any many more) on a single chip.”

The 10-page PDF can be downloaded from Cypress.

Via the contact form.

Here is an app note from Microchip describing how to drive analog inputs of Successive Approximation Register  analog to digital converters.

Driving any A/D Converter (ADC) can be challenging if all  issues and trade-offs are not  well understood from the  beginning. With Successive Approximation Register (SAR) ADCs, the sampling speed and source impedance should be taken into consideration if the device is to be fully utilized. In this application note we will delve into the issues surrounding the SAR Converter’s input and conversion nuances to insure that the converter is handled properly from the beginning of the design phase.

Today we’re is setting up our booth at the Bay Area Maker Faire, and digesting all the tacos from yesterday’s Dangerous Taco Crawl 2012.

Firmware for the Part Ninja is making progress. It is now capable of figuring out the part, and its pinout, with consistency. There’s still some calibration to be done, but all in all we are close to the first test release.

In the office we continue working on our regular bookkeeping and filing in preparation for quarter 2 estimated taxes. We also prepared the free PCB codes for today’s winners.