App note: Simple circuit limits amplifier output

rsdio writes: This is a strange one. It claims to prevent clipping, but still appears to introduce distortion. Perhaps the idea is that soft clipping is preferred to hard clipping? If there were a voltage-controlled gain input, then true peak limiting would be possible, but this seems to trade one form of distortion for another. In any event, if you are interested in audio distortion circuits, then this article should certainly be interesting.

To enable an audio amplifier to accommodate both loud and soft-spoken voices without clipping the loud waveforms, you can implement a nonlinear transfer function by adding a few components to a standard application circuit.

Free PCB Sunday: Oscilloscope v1

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 we’re giving away two Dangerous DSO PCBs. Dangerous DSO is a new logic analyzer/oscilloscope design we’ve been using in the lab. Read the five part series about the design:

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

  • Free PCB Sunday. The classic. Every week, right here on the blog
  • 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 (hopefully back on track now)

Continue reading “Free PCB Sunday: Oscilloscope v1”

Microchip PIC24 development kit for Android

Here is Microchip’s response to the Arduino based hardware for use with Google’s ADK.

Microchip has announced the release of the Microchip PIC24F Accessory Development Start Kit for Android™. This is a standalone board used for evaluating and developing electronic accessories for Google’s Android operating system for smartphones and tablets.

Microchip’s PIC24F Accessory Development Starter Kit for Android (part # DM240415) is available today for $79.99. The PIC32 Accessory Development Starter Kit for Android (part # DM320412) is expected to be available in the third quarter of 2011 for $79.99. The software library, which works with both kits, will be available soon from Microchip support.

OpenHack Europe: Node.js and practical hacking with Javascript


The Yahoo-sponsored OpenHack Europe 2011 is in progress in Bucharest, Romania. One of the latest presentations was Reid Burke’s Achieving Greatness with Node.js. While only the slides are available at this time, they are quite informative and include links to additional content.

If you’re wondering how this relates to open source hardware, see slides 24-25.

Node.js is a prototype-based, object-oriented scripting language. You can download the code to build Node.js for Mac, Linux and Solaris. Windows binaries are also available. Just follow these instructions.

We hope to get more interesting tips and tutorials from this con!

Avviso library for Arduino and Processing sends iOS push alerts

Mike Colagrosso created Avviso, a Processing and Arduino library for sending push alerts to iOS devices using the Prowl API. This would make projects such as Snail Mail Push Alerts a much easier task because a PHP web server is not needed in the set up. The libraries, example code, and set up guide are available on Github.

This is a cool project with comprehensive explanations helpful for newbies.

Via Make.

High-voltage transmit/receive switches

rsdio writes:  These chips look highly flexible for interfacing between different voltage logic circuits

MAX4936, MAX4937, MAX4938, MAX4939
Octal high-voltage transmit/receive switches

Integrated T/R switches significantly reduce component count while reducing power

  • Integrated solution reduces system component count, saving space and improving system reliability
  • Consumes less system power, allowing design flexibility in ultra-portable applications
  • Integrated diodes protect the IC from high-voltage signals while in “receive mode”

Facebook Wordbooker bug update

On Friday and Saturday posts weren’t pushed to Facebook. Problems cropped up after upgrades to the latest WordPress and Wordbooker plugin a few days ago. A Wordbooker reset helped a little yesterday, but then failed again. We’re back on the previous version of Wordbooker now and will monitor the Facebook page all day. We’re really sorry this happened on Facebook PCB Friday, it will be rescheduled.

Free oscilloscope v1 PCB via Facebook comments (try again)

Every Friday we give away some extra PCBs via Facebook. The first few people who comment on this at Facebook get a free PCB. More PCBs via Twitter on Tuesday and the blog every Sunday.

This week we’re giving away two Dangerous DSO PCBs. Dangerous DSO is a new logic analyzer/oscilloscope design we’ve been using in the lab. This is not a finished project, it will not be produced.

Yesterday’s post didn’t get pushed to Facebook. Things looks good now, sorry about the problem.

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

  • Free PCB Sunday. The classic. Every week, right here on the blog
  • 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

Get IR Toy v2 for $22.05 at Seeed Studio, including worldwide shipping.

Continue reading “Free oscilloscope v1 PCB via Facebook comments (try again)”

Hacking police car live video cams


Today embedded systems are proliferating in business and government enterprises. One growing trend is to embed live video cameras in police vehicles, so that command headquarters can have a real time view of what’s going on in and around police cruisers.

Here’s a white paper by digitamunition describing how a penetration tester went about gaining access to view these cruiser-cams. While it tends toward the sensational in its presentation, it nevertheless points to some interesting possibilities.

Web thermostat with Arduino

Boris made a web-based thermostat using Arduino.

The project is designed to control an heating system in order to keep the temperature in a room above a certain value, which can be set from Internet or a Personal Computer by LAN, because ours is not a simple thermostat but a complex unit managed by Arduino, which can connect to a local network with ethernet interface. The thermostat allows many functions, including the publication temperature measured at regular intervals (set by firmware), as well as the state of the boiler (on or off). The datas are published [to Pachube], which provides a database which stores user data, also makes available a series of gadgets to be able to view this data directly into web pages.

Via the contact form.

App note: SMBus-programmable battery chargers

rsdio writes:  SMBus is similar to I2C, and should therefore be easily connected to most PIC or AVR projects.

Highly integrated, 850kHz/500kHz SMBus-programmable battery chargers:

MAX17435/MAX17535, highly integrated SMBus™ battery chargers capable of operating at 850kHz and 500kHz, respectively. Unlike competitive solutions, MAX17435/MAX17436 allow the charge setting to be programmed via the SMBus interface, eliminating the need for external components and improving design flexibility. Programmable settings include charge current, charge voltage, input current limit, relearn voltage, and digital IINP voltage readback. The MAX17435/MAX17535 are ideal for notebook computers, ultra-mobile PCs (UMPCs), mobile internet devices (MIDs), and other battery-powered applications where space is critical.

Continue reading “App note: SMBus-programmable battery chargers”

chipKIT Uno32™ Arduino-compatible prototyping platform

Digilent, Inc. announces the pending release of the chipKIT™ Uno32™. The Uno32 is an Arduino-compatible platform combining Arduino compatibility with the performance of the Microchip PIC32 microcontroller. The Uno32 is the same form factor as the Arduino Uno board and is compatible with Arduino shields. It features a USB serial port interface for connection to the Arduino IDE and can be powered via USB or an external power supply.

The Uno32 board takes advantage of the powerful PIC32MX320F128 microcontroller. This microcontroller features a 32-bit MIPS processor core running at 80Mhz, 128K of flash program memory and 16K of SRAM data memory. In addition to operation within the Arduino development environment, the Uno32 is fully compatible with the advanced Microchip MPLAB development environment and the PICKit3 in-system programmer/debugger.

The board is said to be an open source EAGLE project with EAGLE v5.11 files available for download.

The Uno32 hardware has a May 21, 2011 commercial release date and lists for $26.95. More info is available from Digilent.

Free oscilloscope v1 PCB via Facebook comments

Every Friday we give away some extra PCBs via Facebook. The first few people who comment on this at Facebook get a free PCB. More PCBs via Twitter on Tuesday and the blog every Sunday.

This week we’re giving away two Dangerous DSO PCBs. Dangerous DSO is a new logic analyzer/oscilloscope design we’ve been using in the lab. This is not a finished project, it will not be produced.

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

  • Free PCB Sunday. The classic. Every week, right here on the blog
  • 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

Get IR Toy v2 for $22.05 at Seeed Studio, including worldwide shipping.

Continue reading “Free oscilloscope v1 PCB via Facebook comments”

TI digital temperature sensor


TI has introduced the TMP103 Digital Temperature Sensor with I2C/SMBUS Expanded Interface.

The device features Multiple Device Access (MDA), Global Read/Write Operations,I2C™-/SMBus™-Compatible Interface, 8-bit resolution with accuracy: ±1°C Typ (–10°C to +100°C). The supply range is 1.4V to 3.6V, and the chip comes in a 4-Ball WCSP (DSBGA) package.

According to the press release the sensor draws a maximum of 1 uA while in shutdown mode and 3 uA while in active mode to extend battery life.

The datasheet is available for download. TI has an evaluation module available for $49.

Week in (p)review: May 13, 2011

Facebook free PCB Friday is on the way. Don’t forget to share your current project in the comments or the forum.

This week we threw out our regularly scheduled programming to bring you a five-part series on a prototype open source oscilloscope:

There were a few other things:

Coming this week:

  • We’re leaving for Maker Faire, support will be slower than normal this week
  • Bus Blaster v2 restock is coming, more CoolRunner-II dev-boards too
  • Bus Pirate v3.5, a minor update, should be stocked soon
  • More updated release packages
  • App notes and datasheets all weekend
  • Free PCB Sunday
  • Project status updates on Monday – a look at the Lattice CPLD development board
  • Free PCBs via Twitter on Tuesday
  • Free PCBs via Facebook on Friday (including one later today)
  • Weekly roundup and preview every Friday

What are you hacking this week?

Dangerous DSO part 5: Testing and conclusions

It’s the last day of our week-long Dangerous DSO adventure. Yesterday we simulated the analog front-end and found a few changes to test. First, we’re going to increase the ADC buffer gain to 2. That should make vertical offset adjustment easier. Second, we’re going to try a more refined input range divider with a 900K fixed resistor and 100K trimmer resistor. For background on the front-end see the previous articles.

We hope you enjoyed this series, we had a blast designing the hardware and writing about it. Dangerous DSO v1 PCBs are in the free PCB drawer, if you are serious about building this board please let us know via the contact form. The Dangerous DSO source download includes the v1 design files, the current v1a update, and LTspice simulation files. Now on to the final day of testing!

A big thank you to everyone who helped realize this project. It would not have been possible without you.

Dangerous DSO is a new logic analyzer/oscilloscope design we’ve been using in the lab. This is not a finished project, it will not be produced. We’re posting our current progress to get some feedback. Don’t miss Part 1: There’s so much between 0 and 1, Part 2: Feed and water your ADC, Part 3: Messing with the front end, and Part 4: Over simulated.

Continue reading “Dangerous DSO part 5: Testing and conclusions”

A little Atari 810 disk drive

Rossum has a new project out, a little Atari 810 disk drive:

My first computer was an Atari 400. My first disk drive was the magnificent Atari 810. Overwhelmed by a recent wave of nostalgia from playing Zork for the first time in 30 years I have built a working model of an Atari 810 that uses 8Gig microSD cards instead of 5 1/4 inch floppies to emulate up to 8 drives. Maintaining the relative dimensions of drive to media, the model is somewhat smaller than the original.