From Stairwell to Hallway. The story of the
gallery wall.

post from House of Hepworths "hoh" on 26 January 2012 11:25:46 PM. © House of Hepworths "hoh"

The gallery wall in the stairwell is outta here! {15 months ago…} I tried. I really tried. But this gallery wall has been a thorn in my side since day one. It makes me cray-to-the-zeeee! I thought the issue was the wall color. So I painted the stairwell yellow to match my foyer (I also [...]

This post is sponsored by:
Ribbons and Bows Oh My!
Simple Fit
DISChangers

Read The Full Article:
http://feedproxy.google.com/~r/HouseOfHepworths/~3/hHdq-zUPkBc/

Digg this

Ikea Night Light controlled by an Android Phone

post from Hacked Gadgets - DIY Tech Blog on 26 January 2012 07:48:08 PM. © Hacked Gadgets - DIY Tech Blog

If you ever wanted a way to control your night light from across the room you are in luck. Dan reverse engineered his Ikea night light and stuffed in a bunch of electronics so that it can now be controlled by an Android Phone. Of course remote control is just the beginning, a smart [...]

Read The Full Article:
http://feedproxy.google.com/~r/HackedGadgets/~3/Mbox_O-Jd70/

Digg this

The Etiquette of Inviting Your Ex to Your Wedding

post from How to of the Day on 26 January 2012 07:00:00 PM. © How to of the Day

If party planning isn?t tough enough, now you want to invite your ex to your wedding. And while there is no clear cut etiquette answer on the suitability or otherwise of having an ex at a wedding ? Prince William and Princess Catherine invited ex-flames to their wedding ? it is important that both you and your fiancé are comfortable with the decision and have talked it through. Having an ex at your wedding takes tremendous tact and an extremely understanding fiancé??hopefully one who is confident enough in your relationship to freely admit if he or she feels uncomfortable with having your ex at the wedding or is truthful when stating he or she is totally fine seeing your ex sitting in the congregation. It also matters why you're inviting your ex, as extending an invitation to your ex should be executed with grace and class and only if you parted ways on amicable grounds and no longer have romantic feelings for each other.In this article, you'll learn how to approach the possible complications and the delicacies involved in asking an ex to your wedding.

Read The Full Article:
http://www.wikihow.com/Invite-Your-Ex-to-Your-Wedding

Digg this

Ikea Rolling Dog Bed v2

post from IKEA Hackers on 26 January 2012 05:34:22 PM. © IKEA Hackers

Materials: Ikea chair (Solsta Olarp), Poang footstool lambswool cushion, Ikea large wheels

Description: I purchased the Solsta Olarp chair and the Poang lambswool footstool cushion in the "As Is" department (about $25.00 and $19.99). Any small chair will do (depending on the size of your pet!)

This is a pretty easy hack...

Click to read the rest of the post >>

Read The Full Article:
http://feedproxy.google.com/~r/Ikeahacker/~3/ObNzI9kpPLU/ikea-rolling-dog-bed-v2.
html

Digg this

Makita’s New Star Trek Flashlight

post from Toolmonger on 26 January 2012 05:34:19 PM. © Toolmonger

We love writing about flashlights here at Toolmonger, mostly because flashlights are incredibly useful but somehow almost always seem to end up as the least-thought-out “extra” in a combo count. We think (and suspect you do, too) that flashlights are good for more than just increasing tool count. So I couldn’t help but give a mention to Makita’s new offering, the excitingly-named (kidding) LXLM01. The name might be forgettable, but I thought one thing when I saw this sucker: it looks exactly like those awkward lights everyone carried around on Star Trek: The Next Generation.

No, really. Consider:

Every time I saw someone on Trek carrying one of those things, I thought, “Why don’t they carry it like a normal flashlight?” Makita seems to get this. Yes, the Makita is a very similar shape. But they seem to have incorporated some improvements that clearly escaped Trek’s imagination.

Mentally remove the grip strap, and the Makita’s form factor looks pretty similar to the DeWalt light we thought so highly of. Of course, Makita opted for a six-LED fixed array instead of the DeWalt’s single bright LED in a swivel mount. The downside of this is that you lose the DeWalt’s awesome ability to sit upright on its stand and swivel to provide light in almost any direction. I like the grip strap, though, as at least 50% of the time I find myself carrying the DeWalt light around like a normal flashlight, gripping it around the edges. That strap would make it a lot more stable.

Another consideration is power. The Makita is a lot bigger than it looks. That’s a whopping 18V battery attached to it, instead of the small, compact 12V you see on the DeWalt. That easily accounts for its 50-hour runtime; any battery that’ll drive a recip saw will easily drive six LEDs for long enough for you to forget the last time you charged it.

Anyway, it’ll be interesting to see one of these in person, both to get an idea of whether the strap is really a good thing or not and to find out whether or not this shape of light really works in such a scaled-up size. The light streets for around $20, tool only, and you’ll (surprise) find it included in lots of various combo kits.

18V LXT Li-Ion Cordless LED Flashlight [Makita]
Street Pricing [Google]
Via Amazon [What’s This?]

Read The Full Article:
http://toolmonger.com/2012/01/26/makitas-new-star-trek-flashlight/

Digg this

Hammerhead, Part Deux

post from Toolmonger on 26 January 2012 04:35:21 PM. © Toolmonger

We wrote about Craftsman’s Hammerhead “Auto-Hammer” way back in 2008. Our initial take: it was an interesting solution to a pretty rare problem. When came in possession of one a good bit later, we were surprised to discover that it worked as advertised. (For those of you not familiar, a small anvil inside the hole you see on the head drives a nail with hundreds of short but powerful blows. It feels a little like a pneumatic palm nailer, but it’s battery powered and — as we mentioned back in ’08 — features a much different shape.) But we just couldn’t see it as a serious solution for driving thousands of nails. Rather, we suspected it would find a home more as a specialty tool for tasks like, say, driving a nail in between studs or in other tight spaces.

Enter now the updated version, the Hammerhead G2, pictured above. What, you ask, might they add? Try a light. And a rotating head.

Which actually makes a lot of sense, right? The whole point of this thing, at least as we see it, is for driving nails in hard-to-reach places. So anything they can do to make it more space-flexible seems like a good idea to us. If anything, the rotating head would seem to indicate that Craftsman has finally dropped their vision of a guy in a flannel shirt building a deck with the damn thing and instead accepted the tool’s clear role as problem-solver. Check out the pic they include on the Craftsman site (link below), which shows a guy reaching above his head to drive a nail in what looks like a basement ceiling.

So the bad news: It’s still waaaaay too expensive. $90 seems like too big an ask for a specialty tool that’ll only exit the toolbox on rare occasions. Of course, it’s those specialty tools that (as we’ve pointed out many times) save your ass. Or arm.

What do you think?

NEXTEC 12V G2 Hammerhead [Craftsman]
Street Pricing [Google]
Via Amazon [What’s This?]

Read The Full Article:
http://toolmonger.com/2012/01/26/hammerhead-part-deux/

Digg this

Rolling Dog Beds

post from IKEA Hackers on 26 January 2012 03:34:51 PM. © IKEA Hackers

Materials: Ikea Ektorp Bromma Ottoman, Ikea wheel kit (2), Poang sheepskin stool cover

Description: I made 2 of these. The ottomans were without covers (except the base of one of them) as they were purchased in the "As is" department (about $45.00 @), so were the Poang footstool lambswool cushions ($19.99@).

NOTE: PLEASE MEASURE, MEASURE, MEASURE! These instructions are what worked for me (twice), but I can also "adjust on the fly". Please read through thoroughly before you start. It's worth it!

TOOLS: Sewing machine, Scissors, Staple gun (1/4" staples), hammer (to finish staples), saw to cut feet off ottoman.

MATERIALS: You will need about 94" of Velcro (fuzzy side only, no hook side) and 2' of both hook and loop Velcro, 3/4" wide is fine. Also, 3 yards of 55" wide upholstery fabric, thread to match. 2 Packages of Ikea large wheels. Wide tape to temporarily hold fabric in place (optional).

Click to read the rest of the post >>

Read The Full Article:
http://feedproxy.google.com/~r/Ikeahacker/~3/CcPS5oCA7Cc/rolling-dog-beds.html

Digg this

First Projects, DIYOTD #5

post from ThreadBanger - D.I.Y Fashion & Style on 26 January 2012 03:32:14 PM. © ThreadBanger - D.I.Y Fashion & Style

First Projects, DIYOTD #5
OOTD Threadbanger's DIY first timer picks! Submit pictures of your looks: threadbangerstyle@gmail.com Subscribe to the TB Family: www.youtube.com www.youtube.com www.youtube.com www.youtube.com www.youtube.com Check out our tumblr! threadbanger.tumblr.comFrom:ThreadBangerViews:18417 108ratingsTime:01:13More inHowto & Style

Read The Full Article:
http://feeds.feedblitz.com/~/30037661/0/threadbanger/rss~First-Projects-DIYOTD

Digg this

LED Illuminated Knot Hole Stair Lights

post from Hacked Gadgets - DIY Tech Blog on 26 January 2012 03:23:34 PM. © Hacked Gadgets - DIY Tech Blog

Reclaimed wood was used to replace the stair treads in this stairwell but the knot holes were coming out. Broken glass and epoxy was used to fill the knot holes, a bunch of LED were added to let the knot holes light up. A motion sensor is used to light the stairs for 9 [...]

Read The Full Article:
http://feedproxy.google.com/~r/HackedGadgets/~3/WcKa8tjlZPA/

Digg this

Basics: Power dissipation and electronic
components

post from Evil Mad Scientist Laboratories on 26 January 2012 02:08:29 PM. © Evil Mad Scientist Laboratories

An ever-present challenge in electronic circuit design is selecting suitable components that not only perform their intended task but also will survive under foreseeable operating conditions. A big part of that process is making sure that your components will stay within their safe operating limits in terms of current, voltage, and power. Of those three, the "power" portion is often the most difficult (for both newcomers and experts) because the safe operating area can depend so strongly on the particulars of the situation.

In what follows, we'll introduce some of the basic concepts of power dissipation in electronic components, with an eye towards understanding how to select components for simple circuits with power limitations in mind.

— STARTING SIMPLE —

Let's begin with one of the simplest circuits imaginable: A battery hooked up to a single resistor:

Here, we have a single 9 V battery, and a single 100 Ω (100 Ohm) resistor, hooked up with wires to form a complete circuit.

Easy enough, right? But now a question: If you want to actually build this circuit, how "big" of a 100 Ω resistor do you need to use to make sure that it doesn't overheat? That is to say, can we just use a "regular" ¼ W resistor, like the one shown below, or do we need to go bigger?

To find out, we need to be able to calculate the amount of power that the resistor will dissipate.Here's the general rule for calculating power dissipation:

Power Rule: P = I × V

If a current I flows through through a given element in your circuit, losing voltage V in the process, then the power dissipated by that circuit element is the product of that current and voltage: P = I × V.

Aside:
How can current times voltage end up giving us a "power" measurement?

To understand this, we need to remember what current and voltage physically represent.

Electric current is the rate of flow of electric charge through the circuit, normally expressed in amperes, where 1 ampere = 1 coulomb per second. (The coulomb is the SI unit of electric charge.)

Voltage, or more formally, electric potential, is the potential energy per unit of electric charge --across the circuit element in question. In most cases, you can think of this as the the amount of energy that is "used up" in the element, per unit of charge that passes through. Electric potential is normally measured in volts, where 1 volt = 1 joule per coulomb. (The joule is the SI unit of energy.)

So, if we take a current times a voltage, that gives us the amount of energy that is "used up" in the element, per unit of charge, times the number of those units of charge passing through the element per second:

  1 ampere × 1 volt =
  1 ( coulomb / second ) × 1 ( joule / coulomb ) =
  1 joule / second

The resulting quantity is in units of one joule per second: a rate of flow of energy, better known as power. The SI unit of power is the watt, where 1 watt = 1 joule per second.

Finally then, we have

1 ampere × 1 volt = 1 watt

Back to our circuit! To use the power rule (P = I × V), we need to know both the current through the resistor, and the voltage across the resistor.

First, we use Ohm's law ( V = I × R ), to find the current through the resistor.
• The voltage across the resistor is V = 9 V.
• The resistance of the resistor is R = 100 Ω.

Therefore, the current through the resistor is: I = V / R = 9 V / 100 Ω = 90 mA

Then, we can use the power rule ( P = I × V ), to find the power dissipated by the resistor.
• The current through the resistor is I = 90 mA.
• The voltage across the resistor is V = 9 V.

Therefore, the power dissipated in the resistor is: P = I × V = 90 mA × 9 V = 0.81 W

So can you go ahead and use that 1/4 W resistor?

No, because it would likely fail from overheating. The 100 Ω resistor in this circuit needs to be rated for at least 0.81 W. Generally, one picks the next larger available size, 1 W in this case.

A 1 W resistor typically comes in a much larger physical package, like the one shown here:

(A 1 W, 51 Ω resistor, for size comparison.)

Because a 1 W resistor is much larger physically, it should be able to handle dissipating a higher amount of power, with its higher surface area and wider leads. (It may still get very hot to the touch, but it should not get hot enough that it fails.)

Here's an alternate arrangement that works with four 25 Ω resistors in series (which still adds up to 100 Ω). In this case, the current through each resistor is still 90 mA. But, as there is only one quarter as much voltage across each resistor, there is only one quarter as much power dissipated in each resistor. For this arrangement, one only needs the four resistors to be rated for 1/4 W.

— ON BEYOND RESISTORS —

For our next example, let's consider the following situation: Suppose that you have a circuit that takes input from a 9 V power supply, and has an onboard linear regulator to step the voltage down to 5 V, where everything actually runs. Your load, on the 5 V end, could be as high as 1 A.

What does the power look like in this situation?

The regulator essentially acts like a big variable resistor, that adjusts its resistance as needed to maintain a consistent 5 V output. When the output load is a full 1 A, the output power delivered by the regulator is 5 V × 1 A = 5 W, and the power input to the circuit by the 9 V power supply is 9 W. The voltage dropped across the regulator is 4 V, and at 1 A, that means that 4 W is dissipated by the linear regulator-- also the difference between the power input and the power output.

In each part of this circuit, the power relationship is given by P = I × V. Two parts-- the regulator and the load -- are places where power is dissipated, while across the power supply, P = I × V describes the power input to the system-- the voltage increases as the current travels across the power supply.

Additionally, it is worth noting that we have not said what kind of load is pulling that 1 A. Just because power is being consumed does not necessarily mean that it is being converted into a steady flow of heat energy-- it may be powering a motor, or powering a set of battery chargers.

Aside:
While this is a very common setup for electronics, it's worth pointing out that this is also an incredibly inefficient arrangement: 4/9 of the input power is simply burned off as heat, even when operated at lower currents.

— WHEN THERE ISN'T A SIMPLE "POWER" SPECIFICATION —

Next, a slightly more challenging part: making sure that your regulator can handle the power. While resistors are clearly labeled with their power capacity, linear regulators are not always. In our regulator example above, let's further suppose that we're using a L7805ABV regulator from ST (datasheet here).

(Photo: A typical TO-220 case, the type typically used for medium-power linear regulators)

The L7805ABV is a 5 V linear regulator in a TO-220 package (similar to the one shown above), that is rated for 1.5 A output current and up to 35 V input voltage.

Naively, you might guess that you can hook this right up to 35 V input, and expect to get 1.5 A of output, meaning that the regulator would be radiating 30 V * 1.5 A = 45 W of power. But this is a tiny plastic package-- it actually can't handle that much power. If you look in the datasheet under the "Absolute maximum ratings" section, to try and find how much power it can handle, all that it says is "Internally limited"-- which is anything but clear on its own.

It does turn out that there is an actual power rating, but it's usually somewhat "hidden" within the datasheet. You can figure it out by looking at a couple of related specifications:

• T_OP, Operating junction temperature range: -40 to 125 °C

• R_thJA, Thermal resistance junction-ambient: 50 °C/W

• R_thJC, Thermal resistance junction-case: 5 °C/W

The Operating junction temperature range, T_OP, specifies how hot the "junction"-- the active part of the regulator integrated circuit --can be allowed to get before it goes into thermal shutdown. (The thermal shutdown is the internal limit that makes the regulator power "Internally limited".) For us, that's a maximum of 125 °C.

The thermal resistance junction-ambient R_thJA (Often written as Θ_JA), tells us how hot the junction gets when (1) the regulator is dissipating a given amount of power and (2) the regulator is sitting in open air, at a given ambient temperature. Suppose that we need to design our regulator to only work under modest commercial conditions, that will not exceed 60 °C. If we need to keep the junction temperature under 125 °C, then the maximum temperature rise that we can allow is 65°C. If we have R_thJA of 50 °C/W, then the maximum power dissipation that we can allow is 65/50 = 1.3 W, if we are to prevent the regulator from going into thermal shutdown. That's well below the 4 W that we would expect with a 1 A load current. In fact, we can only tolerate 1.3 W / 4 V = 325 mA of average output current without sending the regulator into thermal shutdown.

This, however, is for the case of the TO-220 radiating to ambient air-- almost a worst-case situation. If we can add a heat sink or otherwise cool the regulator, we can do much better.

The opposite end of the spectrum is given by the other thermal specification: the thermal resistance junction-case, R_thJC. This specifies how much temperature difference you can expect between the junction and the outside of the TO-220 package: only 5 °C/W. This is the relevant number if you can quickly remove heat from the package, for example if you have a very good heat sink hooked up to the outside of the TO-220 package. With a big heat sink and perfect coupling to that heat sink, at 4 W, the junction temperature would rise only 20 °C above the temperature of your heat sink. This represents the absolute minimum heating that you can expect under ideal conditions.

Depending on the engineering requirements, you can start from this point to build a full power budget, to account for the thermal conductivity of every element of your system, from the regulator itself, to the thermal interface pad between it and the heat sink, to the thermal coupling of the heat sink to the ambient air. You can then verify the couplings and relative temperatures of each component with a spot-reading non-contact infrared thermometer. But often, it's a better choice to re-evaluate the situation and see if there's a better way to go about this.

For the present situation, one might consider moving to a surface mount regulator that offers better power handling capability (by using the circuit board as a heat sink) or it may be worth looking into adding a power resistor (or zener diode) before the regulator to drop some most of the voltage outside the regulator package, easing the load on it. Or better yet, seeing if there's a way to build your circuit without the lossy linear regulator stage.

— AFTERWORD —

We have covered the basics of understanding power dissipation in a few simple, dc circuits.

The principles that we have gone over are quite general, and can be used to help understand power consumption in most types of passive elements and even most types of integrated circuits. There are real limitations, however, and one could spend a lifetime learning the nuances of power consumption, particularly at lower currents or high frequencies where small losses that we have neglected become important.

In ac circuits, many things behave very differently, but the power rule still holds in most circumstances: P(t) = I(t) × V(t) for time-varying current and voltage. And, not all regulators are all that lossy: Switching power supplies can convert (for example) 9 V dc to 5 V dc with 90% or higher efficiency-- meaning that with good design, it may only take about 0.6 A at 9 V to produce 5 V at 1 A. But that's a story for another time.

Read The Full Article:
http://www.evilmadscientist.com/article.php/powerdissipation

Digg this