As a rule, from electric lamps it is desirable to obtain the maximum brightness of the glow. However, sometimes lighting is required that will minimally disrupt vision adaptation to darkness. As you know, the human eye can change its photosensitivity over a fairly wide range. This allows, on the one hand, to see at dusk and in poor light, and on the other hand, not to go blind on a bright sunny day. If at night you go out of a well-lit room into the street, then for the first moments almost nothing will be visible, but gradually your eyes will adapt to new conditions. Full adaptation of vision to the dark takes about one hour, after which the eye reaches its maximum sensitivity, which is 200 thousand times higher than daylight. In such conditions, even short-term exposure to bright light (turning on a flashlight, car headlights) greatly reduces the sensitivity of the eyes. However, even with full adaptation to the dark, it may be necessary, for example, to read a map, illuminate the scale of the device, and the like, and this requires artificial lighting. Therefore, lovers of astronomy, as well as anyone who needs to consider something in poor lighting conditions, do not need a bright flashlight.
In the manufacture of an astronomical lantern, one should not strive for excessive miniaturization. The body of an astronomical flashlight should be light and large enough so that in poor lighting conditions it can be easily found (otherwise you will drop it under your feet and look for a flashlight for half an hour). A road soap dish was used as a case. Switches should be such that they can be easily operated by touch and with gloves.
The eye is maximally sensitive to light from a long wavelength of 550 nm (green light), and in the dark, the maximum sensitivity of the eye shifts towards short wavelengths up to 510 nm (effect Purkinje). Therefore, it is preferable to use red LEDs in an astronomical lantern, and not blue, or even more so green. To red light, the sensitivity of the eyes is less, which means that red lighting will less disrupt adaptation to the dark.
In addition to the main lantern, you can make several simple beacons to illuminate various objects. The fact is that few astronomy lovers can afford to have a full-fledged amateur observatory. Most are watching from the balcony. And in a tight space, and even in the dark, you can easily catch your foot and fill up the tripod of a telescope or camera. In addition, suddenly meet in the dark knee with the corner of a drawer or bedside table, the same pleasure is small. Therefore, it is advisable to use the simplest mini flashlights to illuminate tripod legs, sharp corners of furniture, shelves with accessories, and so on. In principle, just an LED fixed with adhesive tape on a 3 V battery of the type 2032 or similar. But, firstly, without a current-limiting resistor, the LED glow is too bright, and secondly, it is desirable to have a switch even in the simplest flashlight. Guided by these considerations, several such beacons were made.
A reed switch paired with a magnet is used as a switch. The 3 V battery mount is self-made. A current-limiting resistor is switched on in series with the LED, its value must be selected so that in the dark, with a direct look at the LED lens, the light does not blind the eyes even at close range. In different beacons, you can use LEDs of different colors to facilitate identification, while remembering that the eye does not have the same sensitivity to light with different wavelengths. You can use flashing LEDs.
In addition, a couple more designs of simple LED lights. The structures specifically described below were not intended for astronomical purposes, but they can easily be adapted for such use.
A simple waterproof flashlight can be made from a film can. We will need: a new jar of film, a 3 V LED, 2-3 reed switches, a 3 V lithium battery 2032 , cotton wool (case filler), a block for a battery from an old flashlight. To ensure water resistance, it is necessary that there are no holes in the body of the flashlight. So as a switch, you can use sealed contacts. For reliable operation, it is better to take 2-3 reed switches, since when turning along the longitudinal axis, the sensitivity of the reed switch changes. So, we collect a flashlight according to the scheme.
We bend the wires so that everything fits in the case, I filled the empty space with cotton so that nothing dangles. We place the circuit in the case. It is important that the film jar is new, i.e. so that the lid closes as tightly as possible. Any magnet will work as a switch. The flashlight of this design continued to work after 10 hours in the water. The cotton wool remained dry. So, long-term lying in a puddle will not damage such a device.
Surely radio amateurs have pads from failed 9 V batteries of the Krona type. On the basis of such a block, you can assemble a simple flashlight that does not actually need a body. An LED is connected to the contacts of the block through a current-limiting resistor.
Outside, the LED and resistor are wrapped with several layers of insulating tape. In the position put on the battery, the flashlight forms a single unit with it.
Thus, it is possible to adapt almost any suitable case and battery for a homemade flashlight, although below 3.5 V you will already need to install LEDs. Thanks for attention. author Denev.
Discuss the article LED FLASHLIGHTS WITH YOUR HANDS
LED strips are now used everywhere and sometimes pieces of such strips, strips with LEDs burned out in places, fall into the hands. And there are a lot of whole, working LEDs and it’s a pity to throw away such goodness, I want to use them somewhere. There are also various types of batteries. In particular, we will consider the elements of a "dead" Ni-Cd (nickel-cadmium) battery. From all this rubbish, you can build a solid home-made lantern, with a high probability better than the factory one.
LED strip how to check
As a rule, LED strips are rated for 12 volts and consist of many independent segments connected in parallel to form a strip. This means that if any element fails, only the corresponding element loses its functionality, the remaining segments of the LED strip continue to work.
Actually, you just need to apply a supply voltage of 12 volts to special contact points that are on each piece of tape. In this case, the voltage will go to all segments of the tape and it will become clear where the non-working sections are.
Each segment consists of 3 LEDs and a current limiting resistor connected in series. If you divide 12 volts by 3 (number of LEDs), you get 4 volts per LED. This is the supply voltage of one LED - 4 volts. I emphasize, since the resistor limits the entire circuit, a voltage of 3.5 volts is enough for the diode. Knowing this voltage, we can directly test any LED on the tape individually. This can be done by touching the leads of the LED with probes connected to a power supply with a voltage of 3.5 volts.
For these purposes, you can use a laboratory, regulated power supply or mobile phone charger. The charger is not recommended to be connected directly to the LED, because its voltage is about 5 volts and theoretically the LED can burn out from a large current. To prevent this from happening, you need to connect the charger through a 100 ohm resistor, so we will limit the current.
I made myself such a simple device - charging from a mobile with crocodiles instead of a plug. It is very convenient for turning on cell phones without a battery, recharging batteries instead of a "frog" and other things. Good for testing LEDs too.
For the LED, the polarity of the voltage is important, if you confuse the plus with the minus, the diode will not light up. This is not a problem, the polarity of each LED is usually indicated on the tape, if not, then you need to try this and that. From the confused pluses or minuses, the diode will not deteriorate.
LED lamp
For a flashlight, it is necessary to make a light-emitting unit, a lamp. Actually, you need to dismantle the LEDs from the tape and group them according to your taste and color, by quantity, brightness and supply voltage.
To remove from the tape, I used a utility knife, carefully cutting off the LEDs directly with pieces of the conductive wires of the tape. I tried to solder, but something I did badly succeeded. Having picked 30-40 pieces, I stopped, more than enough for a flashlight and other crafts.
Connect the LEDs according to a simple rule: 4 volts per 1 or several diodes in parallel. That is, if the assembly is powered from a source of no more than 5 volts, no matter how many LEDs there are, they must be soldered in parallel. If you plan to power the assembly from 12 volts, you need to group 3 consecutive segments with an equal number of diodes in each. Here is an example of an assembly that I soldered from 24 LEDs, dividing them into 3 consecutive sections of 8 pieces. It is rated for 12 volts.
Each of the three sections of this element is designed for a voltage of about 4 volts. The sections are connected in series, so the entire assembly is powered by 12 volts.
Someone writes that LEDs should not be connected in parallel without an individual limiting resistor. Maybe this is correct, but I do not focus on such trifles. For a long service life, in my opinion, it is more important to choose a current-limiting resistor for the entire element and it should be selected not by measuring the current, but by feeling the working LEDs for heating. But more on that later.
I decided to make a flashlight powered by 3 nickel-cadmium cells from a used screwdriver battery. The voltage of each element is 1.2 volts, therefore 3 elements connected in series give 3.6 volts. We will focus on this tension.
By connecting 3 battery cells to 8 parallel diodes, I measured the current - about 180 milliamps. It was decided to make a light-emitting element of 8 LEDs, just as it fits successfully into a reflector from a halogen spot lamp.
As a base, I took a piece of foil fiberglass about 1cmX1cm, it will fit 8 LEDs in two rows. I cut 2 separating strips in the foil - the middle contact will be "-", the two extreme ones will be "+".
For soldering such small parts, my 15-watt soldering iron is too much, or rather too big a sting. You can make a tip for soldering SMD components from a piece of 2.5mm electrical wire. To keep the new tip in place in the large hole in the heater, you can bend the wire in half or add additional pieces of wire to the large hole.
The base is tinned with rosin solder and the LEDs are soldered with polarity. Cathodes ("-") are soldered to the middle strip, and anodes ("+") to the extreme ones. The connecting wires are soldered, the extreme strips are connected by a jumper.
You need to check the soldered structure by connecting it to a 3.5-4 volt source or through a resistor to the phone charger. Do not forget about the polarity of the inclusion. It remains to come up with a flashlight reflector, I took a reflector from a halogen lamp. The light element must be securely fixed in the reflector, for example with glue.
Unfortunately, the photo cannot convey the brightness of the glow of the assembled structure, I’ll say from myself: it doesn’t blind very well!
Battery
To power the flashlight, I decided to use rechargeable batteries from a "dead" screwdriver battery. I took out all 10 elements from the case. The screwdriver worked on this battery for 5-10 minutes and sat down, according to my version, the elements of this battery may well be suitable for the flashlight to work. After all, a flashlight needs currents that are much smaller than for a screwdriver.
I immediately unhooked three elements from the common bundle, they will just give a voltage of 3.6 volts.
I measured the voltage on each element individually - all were about 1.1 V, only one showed 0. Apparently this is a faulty bank, it's in the trash. The rest will still work. Three cans will be enough for my LED assembly.
Having studied the Internet, I brought out important information for myself about nickel-cadmium batteries: the nominal voltage of each cell is 1.2 volts, the bank should be charged to a voltage of 1.4 volts (the voltage on the bank without load), it should be discharged at least 0.9 volts - if several cells are composed in series, then not less than 1 volt per element. You can charge with a current of a tenth of the capacity (in my case 1.2A / h = 0.12A), but in fact it can be large (the screwdriver is charged for no more than an hour, which means the charging currents are at least 1.2A). For training / recovery, it is useful to discharge the battery to 1 V with some load and charge again, so several times. At the same time, estimate the approximate operating time of the flashlight.
So, for three elements connected in series, the parameters are as follows: charging voltage 1.4X3=4.2 volts, nominal voltage 1.2X3=3.6 volts, charge current - which will give a mobile charger with a stabilizer of my manufacture.
The only not clear moment: how to measure the minimum voltage on discharged batteries. Before connecting my lamp, there was a voltage of 3.5 volts on three elements, when connected - 2.8 volts, the voltage is quickly restored when disconnected again to 3.5 volts. I decided this: at the load, the voltage should not fall below 2.7 volts (0.9 V per element), without load it is desirable that there be 3 volts (1 V per element). However, it will take a long time to discharge, the longer you discharge, the more stable the voltage, it stops dropping quickly on the lit LEDs!
I discharged my already discharged batteries for several hours, sometimes turning off the lamp for several minutes. As a result, it turned out 2.71 V with a connected lamp and 3.45 V without a load, I did not dare to discharge further. I note that the LEDs continued to shine, albeit dimly.
Charger for nickel-cadmium batteries
Now you should build a charger for a flashlight. The main requirement is that the output voltage should not exceed 4.2 V.
If you plan to power the charger from any source of more than 6 volts, a simple circuit on KR142EN12A is relevant, this is a very common microcircuit for regulated, stabilized power. Foreign analogue of LM317. Here is a diagram of the charger on this chip:
But this scheme did not fit into my idea - versatility and maximum convenience for charging. After all, for this device you will need to make a transformer with a rectifier or use a ready-made power supply. I decided to make it possible to charge batteries from a mobile phone charger and a computer USB port. For implementation, a more complicated scheme is required:
The field effect transistor for this circuit can be taken from a faulty motherboard and other computer peripherals, I cut it off from an old video card. There are plenty of such transistors on the motherboard near the processor and not only. To be sure of your choice, you need to drive the transistor number into the search and make sure from the datasheets that this is a field transistor with an N-channel.
As a zener diode, I took the TL431 chip, it is found in almost every charger from a mobile phone or in other switching power supplies. The outputs of this microcircuit must be connected as in the figure:
I assembled the circuit on a piece of textolite, immediately provided a USB socket for connection. In addition to the circuit, I soldered one LED near the socket to indicate charging (that voltage is being supplied to the USB port).
A few explanations for the diagram Since the charging circuit will be connected to the battery all the time, the VD2 diode is necessary so that the battery does not discharge through the stabilizer elements. By selecting R4, you need to achieve a voltage of 4.4 V at the specified control point, you need to measure it with the battery unhooked, 0.2 volts is a margin for drawdown. And in general, 4.4 V does not go beyond the recommended voltage for three battery cans.
The charger circuit can be greatly simplified, but you will have to charge only from a 5 V source (the USB port of the computer meets this requirement), if the charger of the phone produces a higher voltage, you cannot use it. According to a simplified scheme, theoretically, batteries can be recharged, but in practice, batteries are charged this way in many factory products.
LED current limit
To prevent overheating of the LEDs, and at the same time reduce the current consumption from the battery, you need to select a current-limiting resistor. I picked it up without any devices, estimating the heat by touch and controlling the brightness of the glow by eye. The selection must be made on a charged battery, you should find the optimal value between heating and brightness. I got a 5.1 ohm resistor.
Working hours
I made several charges and discharges and got the following results: charging time - 7-8 hours, with the lamp continuously on, the battery is discharged to 2.7 V in about 5 hours. However, when turned off for a few minutes, the battery recovers a little and can work for another half an hour, and so on several times. This means that the flashlight will work for a long time if it does not shine all the time, but in practice it does. Even if you use it practically without turning it off, it should be enough for a couple of nights.
Of course, a longer time without interruption was expected, but do not forget that the batteries were taken from a "dead" screwdriver battery.
housing for lantern
The resulting device needs to be placed somewhere, to make some kind of convenient case.
I wanted to place batteries with an LED flashlight in a polypropylene water pipe, but the cans did not even fit into a 32 mm pipe, because the inner diameter of the pipe is much smaller. As a result, I settled on couplings for 32 mm polypropylene. I took 4 couplings and 1 plug, glued them together with glue.
By gluing everything into one structure, we got a very massive lantern, about 4 cm in diameter. If you use any other pipe, you can significantly reduce the size of the lantern.
Having wrapped the whole thing with electrical tape for a better look, we got this lantern:
Afterword
In conclusion, I would like to say a few words about the resulting review. Not every USB port of a computer can charge this flashlight, it all depends on its load capacity, 0.5 A should be enough. For comparison, cell phones, when connected to some computers, may show charging, but in fact there is no charge. In other words, if the computer charges the phone, then the flashlight will also charge.
The FET circuit can be used to charge 1 or 2 battery cells from USB, you just need to adjust the voltage accordingly.
LED light sources are by far the most popular among consumers. LED lights are especially popular. You can get an LED handheld flashlight in different ways: you can buy it in a store or make it yourself.
LED handheld flashlight
Many people who understand at least a little electronics, for various reasons, are increasingly choosing to make such lighting fixtures with their own hands. Therefore, this article will consider several options for how you can independently make a diode handheld flashlight.
Advantages of led lamps
To date, one of the most profitable efficient light sources is the LED. It is able to create a bright luminous flux at low power, and also has a lot of other positive technical characteristics.
Making a flashlight from diodes with your own hands is worth it for the following reasons:
- individual LEDs are not expensive;
- all aspects of the assembly are fairly easy to implement with your own hands;
- homemade lighting fixture can run on batteries (two or one);
Note! Due to the low power consumption of LEDs during operation, there are many schemes where only one battery acts as the power supply for the device. If necessary, it can be replaced with a battery of the appropriate dimensions.
- the presence of simple schemes for assembly.
LEDs and their glow
In addition, the resulting lamp will last much longer than analogues. In this case, you can choose any color of the glow (white, yellow, green, etc.). Naturally, the most relevant colors here will be yellow and white. But, if you need to make a special highlight of some celebration, then you can use LEDs with a more extravagant glow color.
Where can I use and features of the lamp
Very often there is a situation when you need light, but there is no way to install a lighting system and stationary lighting fixtures. In such a situation, a portable lamp will come to the rescue. The LED handheld flashlight, which can be made with one or more batteries, will find extensive use in everyday life:
- it can be used to work in the garden;
- carry out illumination of closets and other premises where there is no illumination;
- use in the garage when inspecting the vehicle in the inspection hole.
Note! If desired, by analogy with a hand-held flashlight, you can make a lamp model that will be easy to install on any surface. In this case, the flashlight will no longer be portable, but a stationary light source.
To make a hand-held LED flashlight with your own hands, you need to remember, first of all, the disadvantages of diodes. Indeed, the widespread use of led-products is hindered by such shortcomings as a non-linear current-voltage characteristic or I-V characteristic, as well as the presence of an “uncomfortable” voltage for power supply. In this regard, all LED lamps contain special voltage converters that operate from inductive energy storage or transformers. In this regard, before proceeding with the self-assembly of such a lamp with your own hands, you need to select the necessary scheme.
If you are going to make a hand-held flashlight from LEDs, it is imperative to think over its power supply. You can make such a lamp on batteries (two or one).
Consider several options for how to make a diode handheld flashlight.
Scheme with superbright LED DFL-OSPW5111Р
This circuit will assume power from two, and not from one, batteries. The scheme for assembling this type of lighting fixture is as follows:
Flashlight Assembly Diagram
This circuit assumes that the lamp is powered by AA batteries. In this case, an ultra-bright DFL-OSPW5111Р LED with a white type of glow, having a brightness of 30 cd and a current consumption of 80 mA, will be taken as a light source.
To make your own mini-flashlight from battery-powered LEDs, you need to stock up on the following materials:
- two batteries. An ordinary “tablet” will suffice, but other types of batteries can be used;
- "pocket" for the power supply;
Note! The best choice would be a "pocket" for the battery, made on an old motherboard.
- superbright diode;
Superbright diode for flashlight
- a button with which a homemade lamp will be turned on;
- glue.
Of the tools in this situation, you will need:
- glue gun;
- solder and soldering iron.
When all the materials and tools are collected, you can get to work:
- First, remove the battery pocket from the old motherboard. For this we need a soldering iron;
Note! Soldering the part should be done very carefully so as not to damage the contacts of the pocket in the process.
- the button to turn on the flashlight should be soldered to the positive pole of the pocket. Only after that, the leg of the LED will be soldered to it;
- the second leg of the diode must be soldered to the negative pole;
- the result is a simple electrical circuit. It will close when the button is pressed, which will lead to the glow of the light source;
- after assembling the circuit, install the battery and check its performance.
Finished lantern
If the circuit was assembled correctly, then when you press the button, the LED will light up. After checking, to increase the strength of the circuit, the electrical soldering of the contacts can be filled with hot glue. After that, we put the chains in the case (you can use it from an old flashlight) and use it to your health.
The advantage of this assembly method is the small dimensions of the lamp, which can easily fit in your pocket.
Second build option
Another way to make a homemade LED flashlight is to use an old fixture that has a burned out light bulb. In this case, you can also power the device with one battery. Here, the following scheme will be used for assembly:
Scheme for assembling a flashlight
Assembly according to this scheme is as follows:
- we take a ferrite ring (it can be removed from a fluorescent lamp) and wind 10 turns of wire on it. The wire must have a cross section of 0.5-0.3 mm;
- after 10 turns have been wound, we make a branch or a loop and again winds 10 turns;
Wrapped Ferrite Ring
- further, according to the scheme, we connect a transformer, an LED, a battery (one finger battery will be enough) and a KT315 transistor. You can also put a capacitor for the brightness of the glow.
Assembled Circuit
If the diode does not shine, then it is necessary to change the polarity of the battery. If it didn’t help, then it was not the battery and you need to check the correct connection of the transistor and the light source. Now we supplement our scheme with the remaining details. The schema should now look like this:
Scheme with additions
When capacitor C1 and diode VD1 are included in the circuit, the diode will begin to shine much brighter.
Diagram visualizations with additions
Now it only remains to choose a resistor. It is best to put a variable resistor of 1.5 kOhm. After that, you need to find the place where the LED will shine the brightest. Further, assembling a flashlight with one battery involves the following steps:
- now we disassemble the old lamp;
- from a narrow one-sided fiberglass we cut out a circle that should correspond to the diameter of the tube of the lighting device;
Note! Under the appropriate diameter of the tube, it is worth selecting all the details of the electrical circuit.
Fitted parts
- Next, we lay out the fee. After that, cut the foil with a knife and tin the board. To do this, the soldering iron must have a special tip. You can make it yourself by winding a wire 1-1.5 mm wide onto the end of the tool. The end of the wire must be sharpened and tinned. It should look something like this;
Prepared soldering iron tip
- solder the parts to the prepared board. It should look like this:
Finished board
- after that, we connect the soldered board with the original circuit and check its performance.
Schema health check
After checking, you need to solder all the details well. It is especially important to properly solder the LED. It is also worth paying attention to the contacts going to one battery. The result should be the following:
Board with soldered LED
Now it remains only to insert everything into the flashlight. After that, the edges of the board can be varnished.
Ready-made LED flashlight
Such a flashlight can be powered even from a single discharged battery.
Varieties of assembly schemes
In order to assemble an LED flashlight with your own hands, you can use a wide variety of schemes and assembly options. By choosing the right scheme, you can even make a flashing lighting fixture. In such a situation, a special flashing LED should be used. Such circuits usually include transistors and several diodes that are connected to various power sources, including batteries.
There are options for assembling a manual diode lamp, when you can do without batteries at all. For example, in such a situation, you can use the following scheme:
Today, LEDs are embedded anywhere - in toys, lighters, household appliances and even in stationery. But the most useful invention with them is, of course, a flashlight. Most of them are autonomous and give out a powerful glow from small batteries. With it you will not get lost in the dark, and when working in a dimly lit room, this tool is simply indispensable.
Small copies of a wide variety of LED flashlights can be bought at almost any store. They are inexpensive, but the build quality can sometimes not please. Whether it's home-made devices that can be made on the basis of the simplest parts. It is interesting, informative and has a developing effect on tinkerers.
Today we will look at another homemade product - an LED flashlight, made literally from improvised parts. Their cost is no more than a few dollars, and the efficiency of the device is higher than that of many factory models. Interesting? Then do it with us.
The principle of operation of the device
This time the LED is connected to the battery only through a 3 ohm resistor. Since it has a ready source of energy, it does not require a storage thyristor and a transistor for voltage distribution, as is the case with an eternal Faraday flashlight. An electronic charging module is used to charge the battery. A tiny micro-module provides protection against voltage surges and does not allow overcharging of the battery. The device is charged from the USB connector, and on the module itself there is a micro USB connector.Required Parts
- 20 ml plastic syringe;
- Lenses for LED flashlight with housing;
- Micro button switch;
- Resistor 3 ohm / 0.25 W;
- A piece of aluminum plate for the radiator;
- Several copper wires;
- Superglue, epoxy or liquid nails.
Assembling a powerful LED flashlight
Preparing the LED with lenses
We take a plastic cap with lenses, and mark the circumference of the radiator. It is needed to cool the LED. On the aluminum plate we mark the mounting grooves, holes and cut out the radiator according to the markings. This can be done, for example, using a drill.
We take out magnifying lenses for a while, now they will not be needed. Glue the radiator plate on the back of the cap with superglue. Holes, grooves at the cap and radiator must match.
The contacts of the LED are tinned and soldered with copper wiring. We protect the contacts with heat shrink tubing, and warm them up with a lighter. We insert an LED with wiring from the front side of the cap.
Processing a flashlight body from a syringe
We unlock the piston with the handle at the syringe, we will no longer need them. Cut off the needle cone with a paint knife.We completely clean the end of the syringe, making holes in it for the LED contacts of the flashlight.
We fasten the cap of the lantern to the end surface of the syringe with any suitable glue, for example, with epoxy resin or liquid nails. Do not forget to place the LED contacts inside the syringe.
Connecting the Micro Charging Module and Battery
We attach terminals with contacts to the lithium battery, and insert it into the syringe body. We tighten the copper contacts to clamp them with the battery case.
The syringe has only a few centimeters of free space, not enough for the charging module. Therefore, it will have to be divided into two parts.
We draw a paint knife in the middle of the module board, and break it along the cut line. Using double tape, we connect both halves of the board together.
The open contacts of the module are tinned, and soldered with copper wiring.
Final assembly of the flashlight
We solder a resistor to the module board, and connect it to the micro button, isolating the contacts with heat shrink.
The remaining three contacts are soldered to the module according to its connection diagram. We connect the micro button last, checking the operation of the LED.
We make a flashlight on LEDs with our own hands
LED flashlight with 3V converter for LED 0.3-1.5V 0.3-1.5
VLEDflash light
Usually, a blue or white LED requires 3 - 3.5v to operate, this circuit allows you to power a blue or white LED with low voltage from a single AA battery.Normally, if you want to light up a blue or white LED you need to provide it with 3 - 3.5 V, like from a 3 V lithium coin cell.
Details:
Light-emitting diode
Ferrite ring (~10 mm diameter)
Winding wire (20 cm)
1kΩ resistor
N-P-N transistor
Battery
Parameters of the used transformer:
The winding going to the LED has ~45 turns wound with 0.25mm wire.
The winding going to the base of the transistor has ~30 turns of 0.1mm wire.
The base resistor in this case has a resistance of about 2K.
Instead of R1, it is desirable to put a tuning resistor, and achieve a current through the diode ~ 22mA, with a fresh battery, measure its resistance, then replacing it with a constant resistor of the received value.
The assembled circuit must work immediately.
There are only 2 reasons why the scheme will not work.
1. the ends of the winding are mixed up.
2. too few turns of the base winding.
Generation disappears, with the number of turns<15.
Put the pieces of wire together and wind around the ring.
Connect the two ends of different wires together.
The circuit can be placed inside a suitable enclosure.
The introduction of such a circuit into a flashlight operating from 3V significantly extends the duration of its operation from one set of batteries.
Variant of execution of a lamp from one battery 1,5v.
The transistor and resistance are placed inside the ferrite ring
White LED powered by a dead AAA battery
Upgrade option "flashlight - handle"
The excitation of the blocking generator shown in the diagram is achieved by a transformer connection at T1. The voltage pulses that occur in the right (according to the scheme) winding are added to the voltage of the power source and fed to the VD1 LED. Of course, it would be possible to exclude the capacitor and resistor in the base circuit of the transistor, but then VT1 and VD1 may fail when using branded batteries with low internal resistance. The resistor sets the operating mode of the transistor, and the capacitor passes the RF component.The circuit used a KT315 transistor (as the cheapest, but any other with a cutoff frequency of 200 MHz or more), an ultra-bright LED. For the manufacture of a transformer, a ferrite ring is required (approximate size 10x6x3 and a permeability of about 1000 HH). The wire diameter is about 0.2-0.3 mm. Two coils of 20 turns each are wound on the ring.
If there is no ring, then a cylinder similar in volume and material can be used. You just have to wind 60-100 turns for each of the coils.
Important point : you need to wind the coils in different directions.
Flashlight photos:
the switch is located in the "fountain pen" button, and the gray metal cylinder conducts current.
We make a cylinder according to the size of the battery.
It can be made from paper, or a piece of any rigid tube can be used.
We make holes along the edges of the cylinder, wrap it with tinned wire, pass the ends of the wire into the holes. We fix both ends, but leave a piece of conductor at one of the ends: so that you can connect the converter to the spiral.
A ferrite ring would not fit into a lantern, so a cylinder of similar material was used.
Cylinder from an inductor from an old TV.
The first coil is about 60 turns.
Then the second, winds in the opposite direction again 60 or so. The threads are held together with glue.
We assemble the converter:
Everything is located inside our case: We unsolder the transistor, the resistor capacitor, solder the spiral on the cylinder, and the coil. The current in the coil windings must go in different directions! That is, if you wound all the windings in one direction, then swap the conclusions of one of them, otherwise generation will not occur.
It turned out the following:
We insert everything inward, and use nuts as side plugs and contacts.
We solder the coil leads to one of the nuts, and the VT1 emitter to the other. Glue. we mark the conclusions: where we will have an output from the coils, we put “-”, where the output from the transistor with the coil we put “+” (so that everything is like in a battery).
Now you should make a "lamp diode".
Attention: on the base should be minus the LED.
Assembly:
As is clear from the figure, the converter is a "substitute" for the second battery. But unlike it, it has three points of contact: with the plus of the battery, with the plus of the LED, and the common body (through the spiral).Its location in the battery compartment is specific: it must be in contact with the positive of the LED.
Modern flashlightwith the mode of operation of the LED powered by constant stabilized current.
The current stabilizer circuit works as follows:
When power is applied to the circuit, transistors T1 and T2 are locked, T3 is open, because an unlocking voltage is applied to its gate through resistor R3. Due to the presence of an inductor L1 in the LED circuit, the current increases smoothly. As the current in the LED circuit increases, the voltage drop across the R5-R4 chain increases, as soon as it reaches about 0.4V, transistor T2 opens, followed by T1, which in turn closes the current switch T3. The increase in current stops, a self-induction current arises in the inductor, which begins to flow through the diode D1 through the LED and the chain of resistors R5-R4. As soon as the current decreases below a certain threshold, transistors T1 and T2 will close, T3 will open, which will lead to a new cycle of energy accumulation in the inductor. In normal mode, the oscillatory process occurs at a frequency of the order of tens of kilohertz.
About details:
Instead of the IRF510 transistor, you can use the IRF530, or any n-channel field-effect key transistor for a current of more than 3A and a voltage of more than 30 V.
Diode D1 must necessarily be with a Schottky barrier for a current of more than 1A, if you put an ordinary even high-frequency type KD212, the efficiency will drop to 75-80%.
The inductor is homemade, it is wound with a wire no thinner than 0.6 mm, better with a bundle of several thinner wires. About 20-30 turns of wire on the B16-B18 armor core are required with a non-magnetic gap of 0.1-0.2 mm or close to 2000NM ferrite. If possible, the thickness of the non-magnetic gap is selected experimentally according to the maximum efficiency of the device. Good results can be obtained with ferrites from imported inductors installed in switching power supplies, as well as in energy-saving lamps. Such cores have the form of a thread spool, do not require a frame and a non-magnetic gap. Coils on toroidal cores made of pressed iron powder, which can be found in computer power supplies (they are wound with output filter inductors), work very well. The non-magnetic gap in such cores is evenly distributed in volume due to the production technology.
The same stabilizer circuit can also be used in conjunction with other batteries and batteries of galvanic cells with a voltage of 9 or 12 volts without any change in the circuit or cell ratings. The higher the supply voltage, the less current the flashlight will consume from the source, its efficiency will remain unchanged. The stabilization current is set by resistors R4 and R5.
If necessary, the current can be increased up to 1A without the use of heat sinks on the parts, only by selecting the resistance of the setting resistors.
The charger for the battery can be left "native" or assembled according to any of the known schemes, or even use an external one to reduce the weight of the flashlight.
LED flashlight from calculator B3-30
The converter is based on the B3-30 calculator circuit, in the switching power supply of which a transformer with a thickness of only 5 mm is used, which has two windings. Using a pulse transformer from an old calculator made it possible to create an economical LED flashlight.
The result is a very simple circuit.
The voltage converter is made according to the scheme of a single-cycle generator with inductive feedback on a transistor VT1 and a transformer T1. The impulse voltage from the windings 1-2 (according to the B3-30 calculator circuit diagram) is rectified by the VD1 diode and fed to the super-bright HL1 LED. Capacitor C3 filter. The design is based on a Chinese-made flashlight designed to install two AA batteries. The transducer is mounted on a printed circuit board made of one-sided foil-coated fiberglass with a thickness of 1.5 mmfig.2sizes that replace one battery and inserted into the flashlight instead of it. A contact made of double-sided foil fiberglass with a diameter of 15 mm is soldered to the end of the board marked with a “+” sign, both sides are connected by a jumper and soldered.After installing all the parts on the board, the “+” end contact and the T1 transformer are filled with hot glue to increase strength. The layout of the lantern is shown infig.3and in a particular case depends on the type of lamp used. In my case, no modification of the lamp was required, the reflector has a contact ring, to which the negative output of the printed circuit board is soldered, and the board itself is attached to the reflector with hot glue. The printed circuit board assembly with the reflector is inserted instead of one battery and clamped with a cover.
The voltage converter uses small parts. Resistors of the MLT-0.125 type, capacitors C1 and C3 are imported, up to 5 mm high. Diode VD1 type 1N5817 with a Schottky barrier, in its absence, you can use any rectifier diode that is suitable for the parameters, preferably germanium due to the lower voltage drop across it. A properly assembled converter does not need to be adjusted if the transformer windings are not reversed, otherwise swap them. In the absence of the above transformer, you can make it yourself. Winding is carried out on a ferrite ring of size K10 * 6 * 3 with a magnetic permeability of 1000-2000. Both windings are wound with PEV2 wire with a diameter of 0.31 to 0.44 mm. The primary winding has 6 turns, the secondary 10 turns. After installing such a transformer on the board and checking its performance, it should be fixed on it with hot glue.Flashlight tests with an AA battery are presented in Table 1.
The test used the cheapest AA battery costing only 3 rubles. The initial voltage under load was 1.28 V. At the output of the converter, the voltage measured on a superbright LED was 2.83 V. The brand of the LED is unknown, the diameter is 10 mm. The total current consumption is 14 mA. The total operating time of the flashlight was 20 hours of continuous operation.
When the voltage on the battery drops below 1V, the brightness drops noticeably.
| Time, h | V batteries, V | V conversion, V |
| 0 | 1,28 | 2,83 |
| 2 | 1,22 | 2,83 |
| 4 | 1,21 | 2,83 |
| 6 | 1,20 | 2,83 |
| 8 | 1,18 | 2,83 |
| 10 | 1,18 | 2.83 |
| 12 | 1,16 | 2.82 |
| 14 | 1,12 | 2.81 |
| 16 | 1,11 | 2.81 |
| 18 | 1,11 | 2.81 |
| 20 | 1,10 | 2.80 |
Homemade flashlight with LEDs
The basis is a flashlight "VARTA" powered by two AA batteries:
Since diodes have a highly non-linear IV characteristic, it is necessary to equip the flashlight with a circuit for operating on LEDs, which will provide a constant brightness of the glow as the battery is discharged and will remain operational at the lowest possible supply voltage.
The heart of the voltage regulator is the MAX756 micropower DC/DC boost converter.
According to the declared characteristics, it works when the input voltage drops to 0.7V.
Switching scheme - typical:
Mounting is carried out in a hinged way.Electrolytic capacitors - tantalum CHIP. They have a low series resistance, which improves efficiency somewhat. Schottky diode - SM5818. Chokes had to be connected in parallel, because. there was no suitable value. Capacitor C2 - K10-17b. LEDs - superbright white L-53PWC "Kingbright".
As you can see in the figure, the whole circuit easily fit into the empty space of the light emitting node.
The output voltage of the stabilizer in this switching circuit is 3.3V. Since the voltage drop across the diodes in the nominal current range (15-30mA) is about 3.1V, the extra 200mV had to be extinguished by a resistor connected in series with the output.
In addition, a small series resistor improves load linearity and circuit stability. This is due to the fact that the diode has a negative TCR, and when it is heated, its direct voltage drop decreases, which leads to a sharp increase in current through the diode, when it is powered from a voltage source. It was not necessary to equalize the currents through the diodes connected in parallel - no difference in brightness was observed by eye. Moreover, the diodes were of the same type and taken from the same box.
Now about the design of the light emitter. As you can see in the photos, the LEDs in the circuit are not soldered tightly, but are a removable part of the structure.
The native light bulb is gutted, and 4 cuts are made in the flange from 4 sides (one was already there). 4 LEDs are arranged symmetrically in a circle. The positive leads (according to the diagram) are soldered to the base near the cuts, and the negative leads are inserted from the inside into the central hole of the base, cut off and also soldered. "Lamp diode", inserted in place of a conventional incandescent light bulb.Testing:
The stabilization of the output voltage (3.3V) continued until the supply voltage dropped to ~1.2V. The load current in this case was about 100mA (~ 25mA per diode). Then the output voltage began to gradually decrease. The circuit has switched to a different mode of operation, in which it no longer stabilizes, but outputs everything it can. In this mode, it worked up to a supply voltage of 0.5V! The output voltage at the same time dropped to 2.7V, and the current from 100mA to 8mA.
A little about efficiency.
The efficiency of the circuit is about 63% with fresh batteries. The fact is that the miniature chokes used in the circuit have an extremely high ohmic resistance - about 1.5 ohmThe solution is a µ-permalloy ring with a permeability of about 50.
40 turns of PEV-0.25 wire, in one layer - it turned out about 80 μG. The active resistance is about 0.2 Ohm, and the saturation current, according to calculations, is more than 3A. We change the output and input electrolyte to 100 microfarads, although without prejudice to efficiency it can be reduced to 47 microfarads.
Scheme of the LED lampon DC/DC converter from Analog Device - ADP1110.
Standard typical connection diagram of ADP1110.
This converter chip, according to the manufacturer's specifications, is available in 8 versions:
| Model | Output voltage |
| ADP1110AN | Adjustable |
| ADP1110AR | Adjustable |
| ADP1110AN-3.3 | 3.3V |
| ADP1110AR-3.3 | 3.3V |
| ADP1110AN-5 | 5V |
| ADP1110AR-5 | 5V |
| ADP1110AN-12 | 12V |
| ADP1110AR-12 | 12V |
Microcircuits with indices "N" and "R" differ only in the type of package: R is more compact.
If you bought a chip with an index of -3.3, you can skip the next paragraph and go to the "Details" item.
If not, I present to your attention another scheme:
It adds two parts to get the required 3.3 volts output to power the LEDs.
The circuit can be improved by taking into account that the LEDs need a current source, not a voltage source, to operate. Changes in the circuit so that it would give out 60mA (20 for each diode), and the diodes will automatically set the voltage to us, the same 3.3-3.9V.
resistor R1 is used to measure the current. The converter is designed in such a way that when the voltage at the FB (Feed Back) pin exceeds 0.22V, it will finish increasing the voltage and current, which means that the value of the resistance R1 is easy to calculate R1 = 0.22V / In, in our case 3.6Ω. Such a circuit helps to stabilize the current, and automatically select the required voltage. Unfortunately, voltage will drop across this resistance, which will lead to a decrease in efficiency, however, practice has shown that it is less than the excess that we chose in the first case. I measured the output voltage and it was 3.4 - 3.6V. The parameters of the diodes in such an inclusion should also be as similar as possible, otherwise the total current of 60mA was not distributed equally between them, and again we will get different luminosity.
Details
1. A choke will fit any 20 to 100 microhenry with a small (less than 0.4 ohm) resistance. The diagram indicates 47 μH. You can make it yourself - wind about 40 turns of PEV-0.25 wire on a µ-permalloy ring with a permeability of about 50, size 10x4x5.
2. Schottky diode. 1N5818, 1N5819, 1N4148 or equivalent. Analog Device DOES NOT RECOMMEND the use of the 1N4001
3. Capacitors. 47-100 microfarads at 6-10 volts. It is recommended to use tantalum.
4. Resistors. A power of 0.125 watts with a resistance of 2 ohms, possibly 300 kΩ and 2.2 kΩ.
5. LEDs. L-53PWC - 4 pieces.
Voltage converter for powering a white LED DFL-OSPW5111P with a brightness of 30 cd at a current of 80 mA and a radiation pattern width of about 12°.
The current consumed from a battery with a voltage of 2.41V is 143mA; in this case, a current of about 70 mA flows through the LED at a voltage of 4.17 V on it. The converter operates at a frequency of 13 kHz, the electrical efficiency is about 0.85.
Transformer T1 is wound on an annular magnetic circuit of size K10x6x3 made of ferrite 2000NM.
The primary and secondary windings of the transformer are wound simultaneously (i.e., in four wires).
The primary winding contains - 2x41 turns of wire PEV-2 0.19,
The secondary winding contains - 2x44 turns of wire PEV-2 0.16.
After winding, the winding leads are connected in accordance with the diagram.
Transistors KT529A of the p-n-p structure can be replaced with KT530A of the n-p-n structure, in this case it is necessary to change the polarity of connecting the GB1 battery and the HL1 LED.
Details are placed on the reflector using hanging mounting. Pay attention to the fact that the contact of the parts with the tin plate of the flashlight, which supplies the “minus” of the GB1 battery, is excluded. The transistors are fastened together with a thin brass clamp, which provides the necessary heat removal, and then glued to the reflector. The LED is placed instead of the incandescent lamp so that it protrudes 0.5 ... 1 mm from the socket for its installation. This improves heat dissipation from the LED and simplifies its installation.
When you first turn on the battery power is supplied through a resistor with a resistance of 18 ... 24 ohms so as not to damage the transistors if the terminals of the transformer T1 are connected incorrectly. If the LED does not shine, it is necessary to swap the extreme terminals of the primary or secondary winding of the transformer. If this does not lead to success, check the serviceability of all elements and the correct installation.
Voltage converter for powering an industrial design LED lamp.
Voltage converter for powering the LED lamp
The circuit is taken from the Zetex manual for the use of ZXSC310 microcircuits.ZXSC310- LED driver chip.
FMMT 617 or FMMT 618.
Schottky diode- almost any brand.
Capacitors C1 = 2.2uF and C2 = 10uFfor surface mounting, 2.2 uF is the value recommended by the manufacturer, and C2 can be set from about 1 to 10 uF
Inductor 68 microhenries at 0.4 A
The inductance and resistor are installed on one side of the board (where there is no print), all other parts are on the other. The only trick is making a 150 milliohm resistor. It can be made from 0.1 mm iron wire, which can be obtained by unwinding the cable. The wire should be annealed on a lighter, carefully wiped with a fine sandpaper, tinned the ends and soldered a piece about 3 cm long into the holes on the board. Further, in the process of tuning, it is necessary, by measuring the current through the diodes, to move the wire, while heating the place of its soldering to the board with a soldering iron.Thus, something like a rheostat is obtained. Having achieved a current of 20 mA, the soldering iron is removed, and an unnecessary piece of wire is cut off. The author came out with a length of about 1 cm.
Flashlight on power source
Rice. 3.A flashlight on a current source, with automatic current equalization in the LEDs, so that the LEDs can be with any spread of parameters (the VD2 LED sets the current that the transistors VT2, VT3 repeat, so the currents in the branches will be the same)
Transistors, of course, should also be the same, but the spread of their parameters is not so critical, so you can take either discrete transistors, or if you can find three integrated transistors in one package, their parameters are as close as possible. Play with the placement of the LEDs, you need to choose a pair of LED-transistor so that the output voltage is minimal, this will increase the efficiency.
The introduction of transistors evened out the brightness, but they have resistance and voltage drops on them, which forces the converter to increase the output level to 4V, to reduce the voltage drop across the transistors, you can propose a circuit in Fig. 4, this is a modified current mirror, instead of the reference voltage Ube = 0.7V in the circuit in Fig. 3, you can use the 0.22V source built into the converter, and maintain it in the VT1 collector using an op-amp, also built into the converter.
Rice. 4.Flashlight on a power source, with automatic current equalization in the LEDs, and with improved efficiency
Because the output of the opamp is of the “open collector” type; it must be “pulled up” to the power supply, which makes the resistor R2. Resistors R3, R4 act as a voltage divider at point V2 by 2, so the opamp will maintain a voltage of 0.22 * 2 = 0.44V at point V2, which is 0.3V less than in the previous case. It is impossible to take a divider even less in order to lower the voltage at point V2. the bipolar transistor has a resistance Rke and during operation, the voltage Uke will drop on it, so that the transistor works correctly V2-V1 must be greater than Uke, for our case 0.22V is enough. However, bipolar transistors can be replaced with field-effect transistors, in which the drain-to-source resistance is much less, this will make it possible to reduce the divider, so that the difference V2-V1 is completely insignificant.
Throttle.The inductor must be taken with a minimum resistance, special attention should be paid to the maximum allowable current, it should be of the order of 400 -1000 mA.
The rating doesn't matter as much as the maximum current, so Analog Devices recommends something between 33 and 180uH. In this case, theoretically, if you do not pay attention to the dimensions, then the larger the inductance, the better in all respects. However, in practice this is not entirely true, because. we have a non-ideal coil, it has active resistance and is not linear, in addition, the key transistor at low voltages will no longer give out 1.5A. Therefore, it is better to try several coils of different types, designs and different ratings in order to choose a coil with the highest efficiency and the smallest minimum input voltage, i.e. the coil with which the flashlight will glow for as long as possible.
Capacitors.C1 can be anything. C2 is better to take tantalum because. it has a small resistance, which increases the efficiency.
Schottky diode.Any for current up to 1A, preferably with minimal resistance and minimal voltage drop.
Transistors.Any with collector current up to 30 mA, coefficient current amplification of the order of 80 with a frequency of up to 100 MHz, KT318 is suitable.
LEDs.You can white NSPW500BS with a glow of 8000mCd from Power Light Systems.
Voltage transformerADP1110, or its replacement ADP1073, to use it, the circuit in Fig. 3 will need to be changed, take a 760μG inductor, and R1 = 0.212 / 60mA = 3.5Ω.
Lantern on ADP3000-ADJ
Parameters:
Power supply 2.8 - 10 V, efficiency approx. 75%, two brightness modes - full and half.
The current through the diodes is 27 mA, in half brightness mode - 13 mA.
In order to obtain high efficiency, it is desirable to use chip components in the circuit.
A properly assembled circuit does not need to be configured.
The disadvantage of the circuit is the high (1.25V) voltage at the FB input (pin 8).
Currently, DC / DC converters with an FB voltage of about 0.3V are being produced, in particular, by Maxim, on which it is realistic to achieve an efficiency above 85%.
Scheme of a lantern on Kr1446PN1.
Resistors R1 and R2 - current sensor. Operational amplifier U2B - amplifies the voltage taken from the current sensor. The gain = R4 / R3 + 1 and is approximately 19. The gain is required so that when the current through the resistors R1 and R2 is 60 mA, the output voltage opens the transistor Q1. By changing these resistors, you can set other stabilization current values.
In principle, an operational amplifier can be omitted. It’s just that instead of R1 and R2 one 10 Ohm resistor is placed, from it the signal through the 1kOhm resistor is fed to the base of the transistor and that’s it. But. This will lead to a decrease in efficiency. On a 10 ohm resistor at a current of 60 mA, 0.6 volts - 36 mW is wasted in vain. In the case of using an operational amplifier, the losses will be:
on a 0.5 Ohm resistor at a current of 60 mA = 1.8 mW + the consumption of the op-amp itself is 0.02 mA, let at 4 Volts = 0.08 mW
= 1.88 mW - significantly less than 36 mW.
About components.
In place of KR1446UD2, any low-power op-amp with a low minimum supply voltage can work, OP193FS would be better, but it is quite expensive. Transistor in SOT23 package. The polar capacitor is smaller - type SS at 10 Volts. Inductance CW68 100uH for 710mA. Although the cutoff current of the converter is 1 A, it works normally. It has the best efficiency. I selected the LEDs for the most identical voltage drop at a current of 20 mA. Assembled a flashlight in a case for two AA batteries. I shortened the place for the batteries to fit the size of AAA batteries, and in the freed space I assembled this circuit by surface mounting. A case for three AA batteries will work well. You will need to install only two, and place the scheme in place of the third.
The efficiency of the resulting device.
Input U I P Output U I P Efficiency
Volt mA mW Volt mA mW %
3.03 90 273 3.53 62 219 80
1.78 180 320 3.53 62 219 68
1.28 290 371 3.53 62 219 59
Replacing the light bulb of the flashlight “Zhuchok” with a module from the companyLuxionLumiledLXHL-NW 98.
We get a dazzlingly bright flashlight, with a very light press (compared to a light bulb).
Modification scheme and module parameters.
StepUP DC-DC converters ADP1110 from Analog devices.
Power supply: 1 or 2 batteries 1.5V operability is maintained up to Uin.=0.9V
Consumption:
*with open switch S1 = 300mA
*with switch closed S1 = 110mA
LED electronic flashlight
Powered by just one AA or AAA AA battery on a microcircuit (KR1446PN1), which is a complete analogue of the MAX756 (MAX731) microcircuit and has almost identical characteristics.
The flashlight is taken as a basis, in which two AA batteries (accumulators) are used as a power source.
The converter board is placed in the lantern instead of the second battery. On one end of the board, a tinned sheet contact is soldered to power the circuit, and on the other, an LED. A circle of the same tin is put on the conclusions of the LED. The diameter of the circle should be slightly larger than the diameter of the reflector base (by 0.2-0.5 mm), into which the cartridge is inserted. One of the terminals of the diode (negative) is soldered to the mug, the second (positive) passes through and is insulated with a piece of PVC or fluoroplastic tubing. The purpose of the circle is twofold. It provides the structure with the necessary rigidity and at the same time serves to close the negative contact of the circuit. A lamp with a cartridge is removed from the lantern in advance and a circuit with an LED is placed instead. Before installation on the board, the LED leads are shortened in such a way as to ensure a tight, play-free fit “in place”. Typically, the length of the leads (excluding soldering to the board) is equal to the length of the protruding part of the fully screwed lamp base.
The connection diagram of the board and the battery is shown in fig. 9.2.
Next, the lantern is assembled and its performance is checked. If the circuit is assembled correctly, then no settings are required.
The design uses standard installation elements: capacitors of the K50-35 type, EC-24 chokes with an inductance of 18-22 μH, LEDs with a brightness of 5-10 cd with a diameter of 5 or 10 mm. Of course, it is also possible to use other LEDs with a supply voltage of 2.4-5 V. The circuit has a sufficient power reserve and allows you to power even LEDs with a brightness of up to 25 cd!
On some test results of this design.
The lantern modified in this way worked with a “fresh” battery without interruption, in the switched on state, for more than 20 hours! For comparison, the same flashlight in the "standard" configuration (that is, with a lamp and two "fresh" batteries from the same batch) worked for only 4 hours.
And one more important point. If rechargeable batteries are used in this design, it is easy to monitor the state of their discharge level. The fact is that the converter on the KR1446PN1 chip starts stably at an input voltage of 0.8-0.9 V. And the glow of the LEDs is consistently bright until the voltage on the battery has reached this critical threshold. The lamp will still burn at this voltage, of course, but it is hardly possible to speak of it as a real light source.
Rice. 9.2Figure 9.3
The printed circuit board of the device is shown in fig. 9.3, and the location of the elements - in fig. 9.4.
Turning the flashlight on and off with one button
The circuit is assembled on a CD4013 D-trigger chip and an IRF630 field effect transistor in the "off" mode. the current consumption of the circuit is practically 0. For stable operation of the D-flip-flop, a filter resistor and a capacitor are connected to the input of the microcircuit, their function is to eliminate contact bounce. It is better not to connect unused microcircuit pins anywhere. The microcircuit operates from 2 to 12 volts; any powerful field-effect transistor can be used as a power switch, because. the drain-source resistance of the field-effect transistor is negligible and does not load the output of the microcircuit.
CD4013A in SO-14 package, analogue to K561TM2, 564TM2
Simple generator circuits.
Allow to feed the LED with ignition voltage 2-3V from 1-1.5V. Short pulses of increased potential open the p-n junction. The efficiency of course decreases, but this device allows you to "squeeze out" almost all of its resource from an autonomous power source.Wire 0.1 mm - 100-300 turns with a tap from the middle, wound on a toroidal ring.
Dimmable LED flashlight with beacon mode
The power supply of the microcircuit - a generator with an adjustable duty cycle (K561LE5 or 564LE5) that controls the electronic key, in the proposed device is carried out from a step-up voltage converter, which allows you to power the lamp from one galvanic cell 1.5.The converter is made on transistors VT1, VT2 according to the transformer oscillator circuit with positive current feedback.
The oscillator circuit with an adjustable duty cycle on the K561LE5 chip mentioned above has been slightly modified in order to improve the linearity of current regulation.
The minimum current consumption of the flashlight with six parallel-connected super-bright L-53MWC white LEDs from Kingbnght is 2.3 mA. The dependence of the current consumption on the number of LEDs is directly proportional.
The "Beacon" mode, when the LEDs flash brightly at a low frequency and then go out, is implemented by setting the brightness control to maximum and turning on the flashlight again. The desired frequency of light flashes is regulated by the selection of the capacitor C3.
The flashlight remains operational when the voltage drops to 1.1v, although the brightness decreases significantly
A field-effect transistor with an insulated gate KP501A (KR1014KT1V) was used as an electronic key. In terms of the control circuit, it is in good agreement with the K561LE5 microcircuit. The KP501A transistor has the following limiting parameters, the drain-source voltage is 240 V; gate-source voltage - 20 V. drain current - 0.18 A; power - 0.5 W
It is permissible to connect transistors in parallel, preferably from the same batch. Possible replacement - KP504 with any letter index. For field-effect transistors IRF540, the supply voltage of the DD1. generated by the converter must be increased to 10 V
In a lamp with six L-53MWC LEDs connected in parallel, the current consumption is approximately equal to 120 mA when the second transistor is connected in parallel to VT3 - 140 mA
Transformer T1 is wound on a ferrite ring 2000NM K10-6 "4.5. The windings are wound in two wires, and the end of the first winding is connected to the beginning of the second winding. The primary winding contains 2-10 turns, the secondary - 2 * 20 turns Wire diameter - 0.37 mm. brand - PEV-2. The inductor is wound on the same magnetic circuit without a gap with the same wire in one layer, the number of turns is 38. The inductance of the inductor is 860 μH
Converter circuit for LED from 0.4 to 3V- powered by one AAA battery. This flashlight increases the input voltage to the required voltage with a simple DC-DC converter.
The output voltage is approximately 7 watts (depending on the voltage of the installed LEDs).
Building the LED Head Lamp
As for the transformer in the DC-DC converter. You must make it yourself. The image shows how to assemble the transformer.
Another version of converters for LEDs _http://belza.cz/ledlight/ledm.htm
Flashlight on a lead-acid sealed battery with a charger.
Lead acid sealed batteries are currently the cheapest. The electrolyte in them is in the form of a gel, so the batteries allow operation in any spatial position and do not produce any harmful fumes. They are characterized by great durability, if you do not allow deep discharge. Theoretically, they are not afraid of overcharging, but this should not be abused. Batteries can be recharged at any time without waiting for them to be completely discharged.
Lead-acid sealed batteries are suitable for use in portable flashlights used in the household, in summer cottages, and in production.
Fig.1. Diagram of an electric lantern
The electrical circuit diagram of a flashlight with a charger for a 6-volt battery, which allows in a simple way to prevent deep discharge of the battery and thus increase its service life, is shown in the figure. It contains a factory-made or self-made transformer power supply and a charger-switching device mounted in the lamp housing.
In the author's version, a standard block designed to power modems is used as a transformer unit. The output AC voltage of the block is 12 or 15 V, the load current is 1 A. There are also such blocks with built-in rectifiers. They are also suitable for this purpose.
The alternating voltage from the transformer unit is supplied to the charging and switching device, which contains a plug for connecting the charger X2, a diode bridge VD1, a current stabilizer (DA1, R1, HL1), a GB battery, a toggle switch S1, an emergency power button S2, an incandescent lamp HL2. Each time the switch S1 is turned on, the battery voltage is supplied to the relay K1, its contacts K1.1 close, supplying current to the base of the transistor VT1. The transistor turns on by passing current through the lamp HL2. The lamp is turned off by switching the toggle switch S1 to its original position, in which the battery is disconnected from the winding of relay K1.
The allowable battery discharge voltage is selected at the level of 4.5 V. It is determined by the turn-on voltage of relay K1. You can change the allowable value of the discharge voltage using the resistor R2. With an increase in the value of the resistor, the allowable discharge voltage increases, and vice versa. If the battery voltage is below 4.5 V, then the relay will not turn on, therefore, voltage will not be applied to the base of the transistor VT1, which turns on the HL2 lamp. This means that the battery needs to be charged. At a voltage of 4.5 V, the illumination created by the flashlight is not bad. In case of emergency, you can turn on the flashlight at low voltage with the S2 button, provided that the S1 toggle switch is first turned on.
A constant voltage can also be applied to the input of the charging-switching device, without paying attention to the polarity of the connected devices.
To transfer the lamp to the charge mode, it is necessary to dock the X1 socket of the transformer unit with the X2 plug located on the lamp body, and then plug the plug (not shown in the figure) of the transformer unit into the 220 V network.
In the above embodiment, a 4.2 Ah battery is used. Therefore, it can be charged with a current of 0.42 A. The battery is charged with direct current. The current stabilizer contains only three parts: an integrated voltage regulator DA1 type KR142EN5A or imported 7805, an HL1 LED and a resistor R1. The LED, in addition to working in a current stabilizer, also performs the function of an indicator of the battery charge mode.
Setting up the electrical circuit of the flashlight is reduced to adjusting the current of the battery charge. The charging current (in amperes) is usually chosen ten times less than the numerical value of the battery capacity (in ampere-hours).
For tuning, it is best to assemble the current stabilizer circuit separately. Instead of a battery load, connect an ammeter for a current of 2 ... 5 A to the connection point of the cathode of the LED and resistor R1. By selecting resistor R1, set the calculated charge current using the ammeter.
Relay K1 - reed switch RES64, passport RS4.569.724. The HL2 lamp consumes a current of approximately 1A.
The KT829 transistor can be used with any letter index. These transistors are composite and have a high current gain of 750. This should be taken into account in case of replacement.
In the author's version, the DA1 chip is installed on a standard ribbed heatsink with dimensions of 40x50x30 mm. Resistor R1 consists of two 12W wirewound resistors connected in series.
Schemes:
REPAIR OF LED FLASHLIGHT
Part ratings (C, D, R)C = 1 uF. R1 = 470 kOhm. R2 = 22 kOhm.
1D, 2D - KD105A (admissible voltage 400V limit current 300 mA.)
Provides:
charging current = 65 - 70mA.
voltage = 3.6V.
LED Treiber PR4401 SOT23
Here you can see what the results of the experiment led to.
The circuit offered to your attention was used to power an LED flashlight, recharge a mobile phone from two metal hydrite batteries, when creating a microcontroller device, a radio microphone. In each case, the operation of the circuit was flawless. The list where you can use the MAX1674 can be continued for a long time.
The easiest way to get a more or less stable current through the LED is to connect it to the unregulated power circuit through a resistor. Keep in mind that the supply voltage must be at least twice the operating voltage of the LED. The current through the LED is calculated by the formula:
I led \u003d (Umax. supply - U working diode) : R1
This scheme is extremely simple and in many cases justified, but it should be used where there is no need to save electricity, and there are no high requirements for reliability.
More stable circuits - based on linear stabilizers:
As stabilizers, it is better to choose adjustable, or fixed voltage, but it should be as close as possible to the voltage on the LED or a string of LEDs connected in series.
Stabilizers like LM 317 are very suitable.
German text:
iel war es, mit nur einer NiCd-Zelle (AAA, 250mAh) eine der neuen ultrahellen LEDs mit 5600mCd zu betreiben. Diese LEDs benötigen 3,6V/20mA. Ich habe Ihre Schaltung zunächst unverändert übernommen, als Induktivität hatte ich allerdings nur eine mit 1,4mH zur Hand. Die Schaltung lief auf Anhieb! Allerdings ließ die Leuchtstärke doch noch zu wünschen übrig. Mehr zufällig stellte ich fest, dass die LED extrem heller wurde, wenn ich ein Spannungsmessgerät parallel zur LED schaltete!??? Tatsächlich waren es nur die Messschnüre, bzw. deren Kapazität, die den Effekt bewirkten. Mit einem Oszilloskop konnte ich dann feststellen, dass in dem Moment die Frequenz stark anstieg. Hm, also habe ich den 100nF-Condensator gegen einen 4.7nF Typ ausgetauscht und schon war die Helligkeit wie gewünscht. Anschließend habe ich dann nur noch durch Ausprobieren die beste Spule aus meiner Sammlung gesucht... Das beste Ergebnis hatte ich mit einem alten Sperrkreis für den 19KHz Pilotton (UKW), aus dem ich die Kreiskapazität entfernt habe. Und hier ist sie nun, die Mini-Taschenlampe:
Sources:
http://pro-radio.ru/
http://radiokot.ru/