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15 Mar 2012


Horto domi is an open hardware raised-bed garden unit with environmental control and monitoring via web-interface thanks to Arduino Ethernet. DIY sensors, such as those collecting moisture and temperature data help monitor the environment within the dome and will eventually be used to automate conditions. The goal is to grow whatever you want, whenever you want, wherever you are. Horto domi is Latin for ‘Garden at home.’ It’s a statement to healthful food independence, a “neo-renaissance” tip of the hat to Arduino, and it sounds like horticultural dome. Particular consideration was taken in this prototype’s design to maximize the mineral and nutrient value of the beyond-organic produce and minimize environmental contamination risks.

Horto domi: the Open Garden - [Link]

25 Feb 2012

Viktor made a sound trigger for his DSLR camera:

Now that I can take pictures of lightning I decided that I also want to be able to trigger my camera with sound.

An op-amp filters and amplifies a microphone signal. The output is fed to a PIC microcontroller that triggers the flash when the sound reaches a certain level. The trigger sound level and shutter delay are set with a pot.  [via]

Lil Bang – Sound trigger for cameras - [Link]

24 Feb 2012

Component packages explained – [via]

Personally, I’ve found all the little acronyms when looking for components to be a little confusing and I’m sure that I’m not the only one that’s been through that. Whats a TSSOP? Whats the difference between SIP and DIP? It can get very frustrating, so this will explain everything for you!

Well there are many different components out there and with that, there have to be different packages to fit different needs such as space availability, prototyping, and different circuit board layouts. The entire list of the more well-known packages, others may be lurking in R&D that we don’t know about, goes something like this : CDIP , PDIP , SPDIP, SIP, SDIP, SOIC, TSOP, SSOP, TSSOP, PLCC, QSOP, VSOP, LQFP, PQFP, CQFP, TQFP, CGBA, and QFN. Its mostly all about space on the board, which kind of package utilizes the precious space on the circuit board the best. So lets start with the descriptions!

Component packages explained - [Link]

24 Feb 2012

SMD Packages explained!. The Funkiester writes – [via]

Hello! Well as a result of all the great feedback from the component packages, I’m doing another post about SMD packages! I may be using some of the terminology from the last post in here as well, so just in case, here is the last post.

First off, SMD means Surface Mount Device; There is another acronym used that means pretty much the same thing which is SMT, and that means Surface Mount Technology. This’ll be describing the various packages that an LED can come in, as well as resistor and the more common capacitor packages as well as many other surface mount devices. The big rule about SMD is that many packages are represented by a 4 digit code. The first two digits indicate its length and the second two digits indicate its width. So an 0603 package would be .06″ x .03″ . Although if it isn’t represented by a 4 digit code, that doesn’t mean that it isn’t an SMD component, all that means is that you’ll have to do a little more searching to find the dimensions of your specific component.

The most common packages are the: 0603 , 0805 , 1206, 2512, and the SOT. although we will be discussing the 0606, 1204, 1210, SOD, PLCC, Chimney-Type, 3528, 5050, A, C, D, E. The space on the board where the SMD will sit is called the footprint, and the footprint is like a little diagram as to where the component is to be soldered on the board and how much space it takes up.

SMD Packages explained! - [Link]

9 Feb 2012

A RC Wien Bridge oscillator outputs a pure sine wave. The frequency depends on the resistor-capacitor combination in the oscillator. Embedded Eric built one using instructions from “Analog Circuit Design“:

I have been slowly reading through Jim Williams “Analog Circuit Design” book. Not slowly because it is boring, it is actually very interesting and a good read; I just get easily distracted and it has been a few weeks since I picked it up. I am about 200 pages or so into it and my favorite chapter so far has been the one where Jim Williams describes the steps he took while recreating William Hewlett’s Model 200A Wien Bridge Oscillator. It is essentially the same project described in Linear Tech’s AN43 Appnote, but with a lot more background and Jim describes the inner workings very conversationally in the book.

Jim’s first iteration of the circuit consisted of a RC Wien Bridge, an LT1037 Opamp and a #327 Lamp. The Lamp is used as a variable resistor that starts out at a very low 98 Ohms DC resistance that helps get the Opamp oscillating (because of the increased gain) and ends up stabilizing at around 235 Ohms once it heats up (thus servo-ing the gain down to an equilibrium point that keeps the circuit oscillating).

RC Wien Bridge oscillator – pure sine wave - [Link]

3 Feb 2012

Sean Breen entered his Digital die (74XX Family) into the Open 7400 Logic Competition – [via]

Here is a rather simple but practical use for digital electronics…..dice! (or in the case a single die)

Unlike many of the kits found online this one does not use a micro controller. The entire circuit is based around 74LSxx logic ICs and a 555 timer for a clock.

7400 competition entry: Digital die (74XX Family) - [Link]

3 Feb 2012

geoffg.ne writes:

Over the years most of us have purchased a few multimeters, and perhaps some of the older ones are still hanging around like faithful friends. You might prefer one ahead of the others, perhaps because it is easier to use and you think that it is probably more accurate, but you wonder just how accurate it is…

Determining the accuracy of a DMM is not easy. Often manufacturers will totally ignore accuracy in their specifications, or if it is a high quality model, they might say something like ±0.02% ±3 digits ±4mV/°C — which does not help either.

This gadget will output a precise 2.500V with an accuracy of ±1 mV. It is great for checking any meter, it does not cost much, and it must be one of the simplest projects around.

MAX6325 Precision Voltage Reference - [Link]

9 Jan 2012

Scott writes:

It’s time for a lecture. I’ve been spending a lot of time creating a DIY dlectrocardiogram and it produces fairly noisy signals. I’ve spent some time and effort researching the best ways to clean-up these signals, and the results are incredibly useful! Therefore, I’ve decided to lightly document these results in a blog entry.

Here’s an example of my magic! I take a noisy recording and turn it into a beautiful trace. See the example figure with the blue traces. How is this possible? Well I’ll explain it for you. Mostly, it boils down to eliminating excess high-frequency sine waves which are in the original recording due to electromagnetic noise. A major source of noise can be from the alternating current passing through wires traveling through the walls of your house or building. My original ECG circuit was highly susceptible to this kind of interference, but my improved ECG circuit eliminates most of this noise. However, noise is still in the trace (see the figure to the left), and it needed to be removed.

Signal Filtering with Python - [Link]

gilbertojunqueira.com writes:

There are many times where you would like to “stabilize” an input signal so that you don’t see the input value “jumping” so much. This is specially true on the MilliVolt Signal range, where nearby noise present can disturb the original signal. In this case, you always have the option of buying some kind of signal conditioner, which handles the filtering function of the raw signal. However, there are many times where the noise problem presents itself after the system is built, in which case a simple software solution is preferable to mitigate the problem.

Simple Software Filter - [Link]

13 Dec 2011

Festivize your bench this holiday season with an oscilloscope Christmas tree – [via]

When I was a little kid, my dad worked at Bell Labs. Every year around Christmas, we’d go visit him at work. One memory which has always stuck with me from my holiday visits was seeing a Christmas tree on an oscilloscope. I was pretty amazed by it. Engineers are a funny bunch — they tend to celebrate holidays in the most uniquely nerdy and wonderful ways, just like kids. When I recently acquired a new ‘scope and wanted to familiarize myself with it, I knew exactly what my test circuit was going to be.

In honor of the nameless BTL engineer whose scope scribbling captivated me as a child, here we are. Maybe the same thing will happen for some other kid. There are a lot of holiday parties coming up. You could put this on one of your scopes at work or at your hackerspace, and some other kid will see it, and it’ll fire their imagination too. It looks pretty neat at any rate, and it’s downright fascinating after a few fortified egg nogs.

Oscilloscope Christmas Tree - [Link]

28 Nov 2011

Random Stories from China @ bunnie’s blog – [via]

Yep, that’s right, the book of iPhone schematics. I snapped that baby up for $4. My feeling is that these schematics probably come from leaks of original Apple sources, because many of the annotations couldn’t be divined from a clean-room reverse engineering job. For example, the above schematics annotate that the AP_UART connection on the dock has a dual-footprint option for a possible drop-in DisplayPort upgrade. Anyways, these schematics are useful as a sourcing guide for cheap components. Any part found in this book has been made in millions-per-week quantities, which is a handy fact to keep in mind when bargain hunting for stable supplies of cheap components.

iPhone schematics and more… - [Link]





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