Rectifier circuit with very low voltage drop featuring a P-channel MOSFET :
Different ways you can protect your circuit from backwards power connections. Diodes, schottky diodes and P channel MOSFETs.
Thanks MickM! Via the forum.
MSProbot Launch Pad robot platform
The MSProbot is one of the projects The Longhorn Engineer featured at the Bay Area Maker Faire 2012. It’s an MSP430 Launch Pad with tank treads, a prototyping area, and sensor breakouts.
Check out our interview with Parker and see the MSProbot in action.
Via the contact form.
#FreePCB via Twitter to 2 random RTs
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
Interesting radio frequency: pirates on SATCOM — 255 MHz
This video highlights another interesting frequency to try with your SDR dongle: 255 MHz. trylleklovn reports that, “Using gqrx with my newsky dvb-t dongle (rtlsdr) to listen to the geostationary SATCOM which is frequently utilized by Brazil radio pirates.”
Gqrx is a free and open source SDR for Linux and Mac designed by amateur radio operator Alexandru Csete, OZ9AEC. It was originally designed for use with the Funcube Dongle (FCD) and Universal Software Radio Peripheral (USRP) devices, and it apparently also works with the RTLSDR. It is powered by GNU Radio and the Qt GUI toolkit.
You can download gqrx from OZ9AEC’s website, where you will also find links to the source code and project details.
What interesting frequencies are you monitoring with SDR?
DP Eagle parts library: FT230X in SSOP-16 footprint
We added the new FTDI FT230X USB-to-serial IC in SSOP-16 footprint to our Eagle parts library. The parts library is public domain, use it however you want.
Not sure where to get parts? Check our master partlist.
Soldering Iron Driver v1.5 assembled and enclosed
Pjkim assembled his Soldering Iron Driver v1.5 free PCB and enclosed it into some Tupperware. He had some problems with the firmware, but he eventually got it to work as intended.
The LCD works, the iron gets hot and I can solder stuff with it! What do you call the first functioning of a soldering iron? First solder? First smoke? First joint?
Will have a more thorough writeup and more pics on my blog soon. And thank you Arhi and Arakis. And Ian too.
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.
Via the forum.
Workshop Update for May 28th, 2012
Today we had meetings, cleaned up the workshop, and worked on our application to the Open Hardware Summit. OHS applications are due the 31st (Thursday), we’ll post ours as soon as it’s done.
We continued updating and cleaning up our Eagle part library, and made some adjustments to a soon-to-be-released PCB.
Capacitor measurement in now implemented into the Part Ninja firmware. The measurement is done by using a comparator to stop a timer when the capacitor is charged to Vref=2.5v ~ VC/2. With the known resistance of either 680, or 470k Ohm, the equation is C=Time/(R*k). Where k is the RC coefficient at which the capacitor is half charged.
#Twatch clock grabs time from network
David turned the Twitter streaming #Twatch into clock that pull time from a SNTP network server. The coding is done, and it’s available for download. David also included documentation in the download package, as well as on his blog.
The zip file has complete source, firmware, and a PowerShell module for using the LCD emulation.
3D Model: Part Ninja v1c
Today’s 3D model is the latest version of the Part Ninja electronic component testing tool. It identifies electronic components like transistors and FETs, determines the pinout, and measures basic specifications. Several SMD footprints are included so surface mount parts can be tested too.
Check out our tutorial on how to build 3D models from Cadsoft Eagle board files, as well as the tutorial onhow to render life like images with Kerkythea.
The models will be published in the Dangerous Prototypes 3D warehouse collection. They are also uploaded to our SVN. You can find them inside the “art” folders in the respective project folders
Bus Blaster with FTjrev
jrev automates the reverse engineering of JTAG connections. The Bus Blaster v2+ with the PicoTap buffer installed works with the FTjrev version for FTDI chips.
Interesting radio frequency: ankle monitors on 314.2 MHz
Now that dongle-based SDRs are exploding in popularity, why not start exploring outside the usual frequency bands? With 64 to 1700+ MHz at your disposal there’s a lot of territory to cover. You’ll find that a number of unusual services occupy some of the lesser know bands not covered by conventional radio scanners.
One example are electronic home monitoring (EHM) devices worn by persons on probation and parole. These devices (such as the one pictured above from International Patent WO2007149391) operate predominantly on 314.2 MHz. Every half hour, the bracelet captures transdermal alcohol readings by taking samples of the insensible perspiration coming off the offender’s skin. The bracelet stores this data and, at pre-determined times, transmits it to the base station via the 314.2 MHz radio link. The base then relays data back to the supervising officer via telephone.
Continue reading “Interesting radio frequency: ankle monitors on 314.2 MHz”
SARduino644 Arduino project board v1.0
Space Age Robotics Arduino-compatible project board hit version 1.0:
I’ve made a new release, v1.0, of the SARduino644 board: There are some more photos and details here
The main changes are better prototyping area (separated from the MCU pins) and more power rails. I also put the auto-reset circuit in (now that I have an FTDI basic that uses the DTR pin to trigger it).
The design files are available in the github repo
Flexible 3D printing material from Shapeways
Shapeways sent an email blast about new flexible 3D printing materials:
We just launched our first fully flexible material for 3D printing. This is our only material that is made to bend, and from what we can tell, the only highly flexible 3D printed material accessible for everyone.
Elasto Plastic is still experimental, so put on your lab coat, check out the design rules and start playing!
App note: Switching regulators for poets
The basics of SMPS design, written by the late analog guru Jim Williams:
A problem is that while everyone agrees that working switching regulators are a good thing, everyone also agrees that they are difficult to get working. Switching regulators, with their high efficiency and small size, are increasingly desirable as overall package sizes shrink. Unfortunately, switching regulators are also one of the most difficult linear circuits to design.
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:
Freescale demo board for S08P family
Freescale is offering their TWR-S08DC-PT60 daughter card, a stand-alone demo board based on the MC9S08P MCU for $14. The board is designed to demonstrate the capabilities of the MC9S08P family and comes pre-programmed with a potentiometer demo, accelerometer demo with orientation/shake/tap/transient modes, flash and EEPROM demo, and a BDM debugger demo. It can be used alone of mounted to the TWR-S08UNIV module to gain access to the Freescale Tower system.
Features include GPIO output through LEDs, Touch Sensing Interface (TSI) with one touch pad, ADC from potentiometer input, and an accelerometer. Additional functionality is provided when used in conjunction with TWR-S08UNIV mother board.
App note: Voltage translation circuits
Here is an app note from Texas Instruments describing how to implement basic voltage translation circuits in your design.
Today’s complex electronic systems involve a multitude of power planes. In order for these mixed-mode systems to operate properly, some type of voltage translation or clamping is necessary. This allows the different input/outputs (I/O) to communicate with each other without damage from overvoltage,
A simple and inexpensive way to accomplish this is with an FET voltage clamp circuit. For this example, the Texas Instruments SN74TVC3306 dual voltage clamp is used. By connecting one I/O of the FET to Vcc, the designer is able to use one of the I/Os on the opposite side as a voltage reference (Vref). This allows the designer to regulate the outgoing voltage by adjusting Vref. Vref is not able to adjust above Vdd – 0.8 V.
28C3 – Introducing Osmo-GMR: Building a Sniffer for the GMR Satphones
In this video from the 28C3 Conference in Berlin, Sylvain Munaut describes the latest member of the Osmocom-family projects, osmo-gmr. This project focuses on the GMR-1 (GEO Mobile Radio) air interface used in some satellite Phones. Sylvain discusses the GMR protocol, the Thuraya network that uses this protocol in the Eurasian/African and Australian continents and finally details how you can capture samples and process them for analysis using osmo-gmr.
The PDF of the slides from this talk can be downloaded here. Read the project details and download code from the osmocom-gmr website.
App note: Low-cost, low-distortion square to sinewave signal converter
Convert square wave clock signals to low distortion sinewaves:
This circuit derives a pure sinewave from a crystal-controlled clock source by using a ring counter to remove the highest-amplitude unwanted harmonics, and filtering the result with an 8th-order lowpass, switched-capacitor elliptic filter
App note: Analog sensor signal conditioning circuits
An analog sensor outputs a voltage relative to whatever it measures, as opposed to digital sensors that provide the reading as a number. These voltages sometimes need to be conditioned to be useful. Microchip describes various analog sensor conditioning circuits:
Analog sensors produce a change in an electrical property to indicate a change in its environment. this change in electrical property needs to be conditioned by an analog circuit before conversion to digital. Further processing occurs in the digital domain but is not addressed in this application note.