App note: MSP430 32-kHz crystal oscillators

in app notes by DP | 0 comments

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MSP430 32-kHz crystal oscillators (PDF!) application note from Texas Instruments:

Selection of the right crystal, correct load circuit, and proper board layout are important for a stable crystal oscillator. This application report summarizes crystal oscillator function and explains the parameters to select the correct crystal for MSP430
ultralow-power operation. In addition, hints and examples for correct board layout are given. The document also contains detailed information on the possible oscillator tests to ensure stable oscillator operation in mass production.

DIY 32ch FPV 5.8ghz LCD

in DirtyPCBs.com, DIY by DP | 0 comments

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Spikey made his own DIY 32ch FPV 5.8ghz LCD with Dirty Board PCB’s:

If you’re like me, you don like buying stuff that’s ready-to-go, but rather build one yourself. We usually spend more money, but it’s way more satisfying I really didn’t want to buy an overly expensive FPV LCD receiver, so I made my own DIY 32ch FPV 5.8ghz LCD, that is compatible with EVERY transmitter on the market now.

More info at Spikey’s project page.

Bus Pirate v3.8 free PCB build

in builds by DP | 0 comments

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@MegaLabs08 tweeted picture of his free Bus Pirate v3.8 PCB build. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

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.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Building a 32K RAM Board

in DIY by DP | 0 comments

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Glitch has posted details on his build of a RAM board for the Challenger III:

With a quantity of 495 prototype boards in hand, it was time to build up a RAM board for the Challenger III. My implementation uses a single 32K x 8 static RAM in DIP packaging, which is split up into eight 4K segments, each of which can be enabled or disabled individually. It’s also expandable to 64K and beyond due to a few design decisions.

Project info at Glitch Works homepage.

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Raspberry Pi web server using flask to control GPIOs

in R-Pi, tutorials by DP | 0 comments

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Rui Santos from Random Nerd Tutorials writes:

In this project you’ll create a standalone web server with a Raspberry Pi that can toggle two LEDs. You can replace those LEDs with any output (like a relay or a transistor).
In order to create the web server you will be using a Python microframework called Flask.

More details at Random Nerd Tutorials homepage.

Check out the video after the break.

Continue reading →

#FreePCB via Twitter to 2 random RTs

in Free PCBs by DP | 0 comments

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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.

Hacking a UART where there never was before

in hacks by DP | 1 comment

Omron

Thanks to Andrew for sharing – check out the full post on their blog, MOAM Industries.

As part of a prototype developed 12 months ago I was tasked with reading measurements from a blood pressure cuff [sphygmomanometer] in real time. Not surprisingly there are no consumer level devices that have a serial interface because what ‘normal’ person would want such a thing!
Initially we considered our own interface for a blood pressure cuff. Just run the pump and take the readings with our own processor and pressure sensor, how hard can it be. Rather difficult it seems, the processing and knowledge required to develop a device to perform even rudimentary readings would have completely blown the time budget. Instead we looked to hack an existing device, enter the Omron RS8.

Details at MOAM Industries blog.

Via the contact form.

Posted in hacks | Tagged , , | 1 Comment

BeagleBone Black GPIO Benchmark

in hacks, R-Pi by DP | 4 comments

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Joonas Pihlajamaa from Code and Life writes, ” I’ve previously made a GPIO benchmark of Raspberry Pi 1 and 2, and have always wanted to see how BeagleBone Black would stack against the Pis. I recently got one so the obvious thing to do was to see how fast the little thing could go.  Turns out, the little thing needed a bit more work than the Pi, but the results were quite interesting.”

More details at Code and Life homepage.

Via the contact form.

48″ T8 Cree LED tube teardown

in Teardowns by DP | 0 comments

Electronupdate has posted a teardown video of 48″ T8 Cree LED tube:

LED based replacements for old T8 fixtures are finally becoming reasonably priced. I see two old competitors back at it again: CREE, and Philips. Both bulbs attractively priced, both 4000K.
I tore down the Cree 1st. Longest circuit board that I have ever seen……

More details at Electronupdate blog.

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Capacitive battery charger

in DirtyPCBs.com by DP | 3 comments

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Marcus Jenkins made a capacitive battery charger using Dirty Board PCB’s to revive rechargeable batteries:

This is really a basic, bare-bones circuit. I’ve prepared the PCB with a view that it could be used as a module in a rather more-sophisticated charging system. You could imagine using a microcontroller (e.g. Arduino, PIC, etc.) to monitor the battery voltage and disconnect the mains input to the charger module when voltage reaches a user-selectable limit. The microcontroller could also have a thermistor probe to attach to the side of the battery with elastic – a basic precaution to try and automatically disconnect in the case unreasonable temperature rise while charging.

Project info at Marcus Jenkins’ blog.  You can order PCB’s for this project here.

Bus Pirate v3.8 free PCB build

in builds by DP | 0 comments

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@joseluisalcoba tweeted picture of his free Bus Pirate v3.8 PCB build. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

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.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 21 comments

IRToy

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 →

Posted in Free PCBs | Tagged | 21 Comments

110v temperature controlled soldering station build no. 2

in project logs by DP | 0 comments

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Mike Doughty from PCB Smoke shared his DIY 110v temperature controlled soldering station in the project log forum:

This project is build number 2 of a 110v temperature controlled soldering station. It is a follow-up post to the project that I was working on last October.
Blog post with complete details here.
This version has a couple of improvements over the first build. This new soldering iron is a better unit and was less expensive than the first one.
A chisel tip plus a selection of other tips was available for this soldering iron instead of being limited to a conical tip only.

More details at PCB Smoke project page.

Via the forum.

Check out the video after the break. Continue reading →

USB curve tracer for NPN transistors

in open source, USB by DP | 10 comments

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Dilshan Jayakody documented his USB port base NPN transistor curve tracer project:

Curve tracer is an electronic test instrument to analyze the characteristics of transistors and other discrete semiconductors. In this post we construct USB base curve tracer to analyze properties of NPN transistors. This curve tracer is build around Microchip’s PIC18F4550 MCU and it use simple Windows based GUI application to plot captured data of a transistor.
In this design PIC18F4550 MCU is used to establish USB connectivity, perform voltage readings and control current/voltage flow into the test subject. To minimize the cost and to make it simple, we use R2R ladder circuit to generate discrete collector-emitter voltage levels for the transistor on test. In each scan session collector-emitter voltage level get increase from 0V to 7.5V in 256 steps. In this design, “tracer” scans the transistor for 7 base current levels which are in between 7µA to 60µA. In viewer application collector-emitter voltage levels are plotted on x-axis and collector current is plotted on y-axis.

More details at Dilshan Jayakody’s blog.

Project files available at sourceforge.net.

App note: The LED versus LCD decision

in app notes by DP | 0 comments

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Choosing between two display types, LED and LCD discussed in this application note from Murata. Link here (PDF)

Users of contemporary digital panel meters (DPMs) have a variety of options available to them. While options are nice, they invariably mean more choices have to be made. After determining what meter resolution one requires, the next most basic decision is usually which type of display to use liquid crystal or light emitting diode?
Traditionally, liquid crystal displays (LCDs) have been the obvious choice for outdoor/daylight applications and/or for applications requiring extremely low power consumption (current drains less than 15mA). Light emitting diode (LED) displays, with their comparatively low light intensities and relatively high current drains, have been excluded from these more demanding applications.
Recent DATEL innovations, most notably the introduction of extremely low-power LED displays, have complicated the once straightforward, LED/LCD decision.

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App note: EFM32 Energy Modes

in app notes by DP | 0 comments

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Application note from Silicon Labs on their EFM32 energy saving microcontrollers, some interesting points are discussed how these type of microcontrollers can conserve power. Link here (PDF)

In battery powered microcontroller applications, energy saving is essential. By reducing the current consumption, the mean time between battery charging / replacement can be significantly increased. Following these principles will drastically reduce the current consumption:
• Use appropriate Energy Modes
• Exploit low energy peripherals
• Turn off unused modules / peripherals
• Disable clocks to unused modules / peripherals
• Reduce clock frequency
• Lower the operating voltage
The EFM32 supports extensive usage of all these principles.