Frequently Asked Questions (FAQ) for Battery Led Light Small

You don't even need to go all super-futuristic for this. It's almost possible today. Get a balloon filled with helium, and put a small LED button-battery powered light source inside it. Secure it with some ultra-fine fishing line, attach the other end to your clothing, and you're basically done.

Now if you want it to look nicer and slightly more future-techy, you can replace the balloon with specially molded ultra-thin lightweight composite, maybe with a well-placed strut to keep the LED centralized (and possibly provide an external power switch and means of replacing the battery), and replace and the fishing line with carbon mono-filament. Anything else is just over-engineering

------

Dynamo hub lighting system recommendation

Staying lit while totally stopped, for example at a junction, is a function of the light. It's definitely worthwhile, and a modern LED dynamo light with standlight function will give reasonable light for quite a while when stopped.

Theft of dynamo lights seems to be rare, but if you are worried, consider using non-standard screws or bolts to make it harder to remove them, not making them easily removeable like battery lights.

If you like the feeling of having the absolute best, even if it was pricy, get the Schmidt, but the better Shimano models are very nearly as good and quite a bit cheaper, and a BM Cyo is very nearly as good as the Schmidt light.

------

AM Radio Wave LED Indicator

Your simple circuit has no voltage gain and instead it has tremendous voltage loss so an AM signal that is 3.4V peak will barely light the LED.The LED needs 2V if it is a red one. The emitter-follower transistor needs a base voltage of 2.7V for it to light the LED. The rectifier diode input needs to be 3.4V for the circuit to light the LED.An AM radio has a voltage amplifier with plenty of gain.

------

How can I improvise a camping lantern from my flashlight?

How can I improvise my flashlight for camping?Try using a magnetic similar to the one in this image:Simply lay down a thick piece of felt between the magnet and your car to avoid scratching the paint. Once the magnet is in place, you can tie your flashlight to the magnet.Magnets are commonly used to hold beacon lights on the roof of cars and trucks.

------

What's the relationship between volts and amperes in batteries?

A battery is a collection of cells; the voltage of each cell is determined my its chemistry, plus a small factor dependant on how fully charged it is.Current delivery is limited by the internal resistance of the battery. This depends mostly on the surface area of the cell electrodes, which is why larger battery packs are inevitably needed for high current applications.

You can measure the internal resistance of a battery by looking at how the voltage drops for an increased current draw then applying Ohm's law. That would enable you to answer (4).70 diodes drawing 50ma each would be 3.5 amps, which is quite a lot. For that level of current I would look at R/C battery packs; "3S" ones have a nominal voltage of 11.1V. This is slightly above the rated voltage of the LEDs, so add a 47 or 36 ohm 1/4 watt resistor in series with each pair of laser diodes.

------

Lighted SPST switch waiting problems

two possibilities .

your circuit looks fine . have you connected to the correct terminals on the switches ?

Or it could be that your battery is too small . In that case the igniter would draw so much current that the battery voltage falls too low to ignite or light the LEDs. I would monitor the battery voltage with a multimeter whilst operating the switches. I assume that the LEDs have an internal resistor . If they do not you will need to add series resistors of around 1K.

------

How do I go about building a charger circuit?

2.1 If this design is too complex for you, buy some cheap Li-Ion battery charger and use its electronics - for example this one.Charging time for the Li-Ion batteries can be as small as 1h, but if it is too big for you, you can use another trick - instead of waiting for battery to charge, use two replaceable batteries mounted externally to the robot and design the charger to have two connect places. Then learn your robot to leave the discharged battery in the charger and to get the charged one from the second docking place.

------

Charging mobile phone using the battery of a rechargeable bike light?

Answer No, you need an item designed for this purpose.Whether yours do or not, it totally depends on the product. Many modern lights are charged by USB, but they can't supply USB to other devices.

There are other products which combine a USB battery with a light, but the batteries inside these are much larger than a plain light. Notice 80% of this item is batteries, and it probably weighs quite a bit.That claims to be a Rugged 3Watt speaker and hands free kit with 8Ah Power Bank, in-built Charging Cable, LED Flash Torch and Bike Mount. The price is not small.

------

Best way to illuminate a tent?

Some of the Mammut headlamps can be fitted with an optional diffuser for ambient lighting. Haven't tried it, but it looks like it could be a neat solution.Mammut TR1 Headlamp

------

How to capture a swinging pendulum?

Consider adding a light source to the bob itself, such as an LED. Set your exposure for several periods of the pendulum, and flash your external light source at the extremes. This attached light source should trace a clear path, and the flashes should illuminate the extremes.

LEDs are fairly directional, so you should be able to control how much light leaks onto the bob. The LED can be powered by a small battery attached to the bob, or fed through the pendulum's cable

------

Why do DSLR cameras still use monochrome LCD as their top displays?

Segment LCD is a technology with the lowest power consumption of all available display technologies and those are more than visible on sunlight or any kind of strong light without any need for background lightning (except at night). Very useful for battery operated devices. It's also the cheapest possible display technology. They are also extremely robust.

Remember those cheap digital wristwatches? The battery is extra small in them and they still manage to keep going for a year or two...A few words from one of many LCD manufacturers:

------

Why do LED Lights Flicker on Low Dimmer Setting

LED flickers, because it is a light emitting diode (a solid state lamp). The Lamp will only light when its power cycle is "on". A dimmer in essence, SLOWS DOWN THE CYCLE TIME, therefore slowing down the time frame in which a cycle is repeated. So, the lamp appears to flicker, because it is turning ON and OFF!

------

What happens if an LED is connected to a supply voltage greater than its voltage drop?

We never were told if the battery used in the video was a Chinese "Super Heavy Duty" carbon-zinc type that was leaking in its package for a year and bought at The Dollar Store, or if it was a new modern Name-Brand alkaline one. BIG difference

------

volt timer passes small amount of current when off

Another solution: plug a small incandescent lamp into the timer, in parallel with the LED string. The current draw of the incandescent should keep the LED string from glowing when the timer is supposedly "off".Ideally, this could be something as small as a 4W night light. But, the details of where you're installing this could make it impractical

------

LED and motor connected in parallel

You shouldn't be driving a red LED from a 3V coin cell. Red LED voltage drop is typically on the order of 1.8V. You're overloading the LED by doing it this way, and it is likely sinking the current that should be going to your motor. Minimally, you need a resistor in series with the LED to limit its current

------

What makes a good head lamp?

Some look for replaceable bulbs, but headlamps are so cheap and long lasting that I do not. After all, who can say there will be bulbs available for it 10 years from now when I need them.You've already mentioned battery life and brightness.

Some LEDs cannot be used with Lithium batteries, if that matters to you

------

Orange and other artifacts in photos from film camera

It is difficult to differentiate between a light leak caused during developing or in-the-camera leaks. Also, a leak could be due to improper handing during loading and unloading. By the way, I was surprised by the fact that you changed the light seal of the camera back. These are difficult parts to find. Good for you!

Consider that camera light leak still plunges you.Procure a tiny key-chain flashlight. One that stays on after the button is press. Place a lit one inside the camera. Now retire to a dark room and examine the camera from all angles. Dont pass judgement to quick, take time to dark adapt. This procedure can catch most camera leak.

------

What kind of light can I install in a small, low-ceiling coat closet?

On a recent inspection, my local inspector disapproved an open bulb in a surface mounted porcelain socket in a closet, but indicated that a bulb fully enclosed by a glass dome would be acceptable. This was approved and cost less than $15:While LED and CFL are lower draw and cooler, you could use one of those bulbs with a standard base in this type fixture.I suggest you check with your local building department to see if surface mounts are acceptable.

------

Non-contact sensor in soap dispenser

Passive Infrared detectors. They're essentially IR cameras, albeit very crude (low resolution) ones, that notice a moving object against a stationary background by comparing successive "images". It's the same motion-detection technology used in home security alarms

------

Why does the LED turn off if the high current is going through the short?

A short circuit is really just a parallel circuit added where it shouldn't be. If the parallel circuit is low resistance then it takes most of the current. You only need to know the calculations for resistance in parallel to workout whats going to happen when your circuit is shorted, unless you've added more complex components to parts of the circuit. (I'm not very experienced, if this is wrong please comment)

------

Inserting Capacitor into CIrcuit causes LED to fade - Why?

Capacitor works like a toilet tank: it keeps the water flowing, until it fills. Then you can discharge it (flush). After you flushed water flows faster, but slows down. Capacitors do similar thing with electricity.

------

Bluetooth receiver as an on/off switch

You are looking for Bluetooth 4.0 I think. Lower BT versions are not made for energy efficient systems. Notice you probably want to stay connected to the BT device because:There are also low power modes for the BT (park, hold and sniff), which you can use to quickly change to the active (connected) status for data transmission.Sorry for the mixed up ideas in the response, it is better if you read a little bit about BT versions and architecture if you are interested. Otherwise my advise is, again, go for BT version 4

------

How does the capacitor in a debouncing circuit work?

A capacitor can, for many purposes, be considered as a very small rechargeable battery. It will only pass current while charging or discharging.Most LEDs require at least 2 volts to light - for your circuit to work at all, the voltage source should be at least 3 volts. Then you might see the LED continue to glow for a fraction of a second after you open the switch, as the capacitor charges

------

Why can't I light a LED with a 1.5 V battery?

LEDs don't work like ordinary (incandescence) light bulbs. Main differences (a bit simplified for very beginners):You also ask why all this happens, but the answer is fairly complex, since it depends on the physical structure of the semiconductor crystal inside the diode. The physical explanation lies in quantum mechanics and solid-state physics, really tough subjects. The Wikipedia article on LEDs only scrapes the surface of the internal workings of the LEDs and still is fairly complex