by Deddieslab :
I have a couple of front door LED lights which I would like to switch on automatically during the evening/night. The two conventional methods that are commonly available had their disadvantages:
A timer switch is the easiest and cheapest solution, but doesn’t take into account day light savings. Besides that, in Einhoven, the Netherlands where I live in december the sun sets around 16:30 while in June it doesn’t get dark before 22:00. A simple timer doesn’t take that into account either.
Since you only want the lights on when it gets dark, instead of time you can also use a light sensor to distinguish day and night. You have these front door lights that have this built in. The problem that I had with these devices is that they start bouncing (‘flickering’) around sunset/sunrise. They constantly turn on/off which causes damage to the LED lights I was using. This cost me already several expensive led lights.
Frontdoor light switch based on local sunset/sunrise - [Link]
by dreded @ dredx.com:
In my home I have a fairly long hallway that has light switches at either end but 99% of the time we enter the hallway from the middle where there is no switch. So I decided I needed to do something about this as walking down a dark hallway all the time was annoying.
I have seen a fair number of people use an arduino or even a standalone ATTiny85 with a El cheapo HC-SR501 which can be found on ebay for about $1.25 each and I find these things work fantastic, they have an excellent range and detection spread.
Motion activated lighting without a Micro-Controller - [Link]
App note (PDF) on automobile flashers from Texas Instruments:
This Application note presents the design of a low cost, flasher circuit with short circuit protection. The design incorporates the entire recommended design feature set for two wheeler flashers and includes low/high voltage operation, half load frequency doubling, and short circuit protection.
App note: Design of a low cost, 45W flasher with short circuit protection using LM2902 - [Link]
Mr.Fishers3 @ instructables.com writes:
Ever looked at a lightbulb and thought that doesn’t look too complicated, I bet I could make one? With this Instructable you can!
This lightbulb is made entirely out of simple, mostly household materials requiring very little in special equipment. The basic construction includes a glass jar filled with CO2 and a graphite filament(Pencil Lead). This makes it a carbon filament bulb analogous to those made by Edison before tungsten became the norm.
Homemade Lightbulb - [Link]
Building flashlights seems to be a fixation of mine. I built my first one at age 5 or so, and now that I’m nearing ten times that age, I’m still building flashlights. This time the project of choice was a high power LED flashlight with several interesting features:
A high power LED flashlight - [Link]
This GU10 LED spot light is cheap (£3 including postage) and bright. But it’s also lethal! There’s a 50% chance of putting live mains within a few microns of the metal casing (which is what you’ll be holding when you insert it) and there’s no earth to protect you. It’s like playing Russian Roulette with 240v AC mains. This sort of thing gives new technology a bad name. Avoid it if you want to stay alive.
Dangerous GU10 LED Spot Light is Cheap and Bright but could Kill You – Seriously - [Link]
A project with only 2 parts, but is great for addressing an everyday situation that is irritating at best and dangerous at worst. This circuit protects the bulb in flashlights from high switch-on current to make the bulb last longer.
For a standard incandescent flashlight, this is a easy little modification make your flashlight bulbs last longer. High powered flashlights typically run their bulbs hot to get a brighter light from them. They also have a much lower on-resistance when cold, so that when you turn them on, the bulb passes a much higher current than it was designed for. This is why the most common time for a bulb failure is when turning it on.
The transistor and resistor limit the current while turning on the circuit and protect the bulb from an initial high current turn on. A simple resistor in series with the bulb might be a tempting option, but there are a couple problems with that approach. Just adding a resistor would reduce the voltage available to the bulb, and aid longevity, but that would reduce the brightness. The resistor would also be wasting energy getting hot instead of using that energy for light. This solution is better in that it limits current at startup and wastes very little energy when in use and when off.
In this application, it might be easier to insert the batteries in the flashlight “backwards” so the circuit connections and parts have the best fit in the body of the flashlight. Flashlight design was stagnant for decades, but now there are many new technologies available, and in some cases, it can even be easy to bring some of them to an older one you already have. In addition to this circuit, you could also take advantage of newer LED and battery technology to really increase the brightness, “on” time, and lamp life of your old flashlight.
Soft Start For Flashlights - [Link]
With OLEDs approaching production maturity, Osram has announced that it is researching another technology that could change the world of lighting: light emitting foils produced in a printing process. The foils are based on light-emitting electrochemical cells made from organic materials, known as organic light-emitting electrochemical cells (OLECs). Although similar to OLEDs, they have a conductive and light-emitting layer containing a liquid material instead of a solid material. This active layer contains freely mobile ions in the liquid phase. When a voltage is applied to the active layer, the ions migrate to the edge. This allows charge carriers to be injected into the layer, where they recombine to emit light in the same way as a light-emitting diode. With suitable combinations of materials, any desired color of light can be obtained. [via]
Printed Light-Emitting Foils Could Challenge OLEDs - [Link]
I really liked the idea of controlling my “Home Theatre” lights with a remote (TV or other), this would save me the exhausting task of heaving myself off the couch to turn the lights on or off.
I found one of my remotes has a spare power button, its one of those stupid “universal” remotes that comes with DVD players or TVs but only work if you have all the same brand equipment, I don’t so this made a good option for a light switch.
Remote Controlled Home Theatre Lights - [Link]
Publitek European Ed writes:
Daylight harvesting is becoming increasingly important in the design and implementation of commercial lighting systems. Being able to integrate the natural light from windows with flexible, controllable sources of lighting helps improve the work environment and cut energy bills.
Being able to have closer control of the lighting systems in a commercial environment is a key element to this strategy and energy harvesting can play an important role. Being able to have flexible placement of control pads for a commercial lighting system is an important requirement as office space is regularly reconfigured as existing clients grow and change their requirements and new clients have new requirements.
Smart Lighting in the Enterprise - [Link]