Do not throw away your used batteries, they may still serve you. A new alkaline battery has a voltage of 1.5 volts, which decreases as it is used. Eventually the voltage becomes too low for most devices to operate. However, the remaining 15% of the charge can be “pulled” out of the battery using a special technique called the “Joule thief”. This is quite enough to light the white LED of the flashlight, which we will try to make.
The Joule Thief circuit increases the battery's depleting voltage, but does so in rapid bursts. As a result, we will see a constant glow, although in reality the LED will turn on and off quickly.
So what we need:
Required Tools
- soldering iron;
- wire stripper;
- scissors;
- Double-sided tape.
Necessary materials
- battery holder with contacts;
- 10mm super bright white LED;
- a piece of wire from an old network cable;
- toroidal transformer core (2 cm);
- button;
- resistor 1 kOhm;
- round breadboard (diameter 2-3 cm);
- transistor 2N2222 NPN or similar;
- used AAA, AA, C or D alkaline battery.
Let's start building the lantern:
1. Prepare the battery holder
Our battery holder model has a negative (with spring contact and black wire) and positive (red wire) contacts. Pass the wires through the holes in the housing so that they come out as shown in the figure. Pay attention to how the negative wire runs from the side of the spring contact.
2. Attach a button
We take double-sided tape and attach the button to the battery holder from the negative contact side.
3. Solder the button
We cut the negative wire of the battery holder near the button, strip the ends of the wires and solder them to the button contacts.
4. Insert the LED
Take the PCB and insert the LED into the center so that its legs go through the board.
5. Bend and solder the LED legs
Bend the ends of the LED as shown in the picture and solder them to the vias on the board.
6. Install the transistor
Look at the transistor packaging or search online to see which element legs correspond to the emitter, base, and collector. Install and solder it onto the breadboard above the LED so that the emitter of the transistor is connected to the upward-curved end of the LED, and the collector to the side-curved end (see figure).
7. Install resistor
Install a resistor on the board directly below the LED. Connect one leg of the resistor to the base of the transistor, and bend the second leg and move it to the side.
8. Prepare the battery holder wires
Shorten the wires coming from the battery holder so that they protrude 3-4 cm from the case. Then strip and tin their ends.
9. Attach the development board to the battery holder
Pass the wires obtained in the previous step through the breadboard as shown in the figure. Please note that the positive wire should go to the right side of the LED, and the negative wire to the left.
10. Solder the battery holder wires
Bend and solder the black wire to the LED leg, bent to the side (see photo).
11. Insert wires
Cut two 50cm wires, strip and tin them on one side. Connect the wires to the breadboard. One - to the red wire from the battery (passing through the via hole). The second one goes to the collector of the transistor.
12. Solder the toroid wires
Solder the wires from the previous step. They will be needed to hold the core of the toroidal transformer.
13. Pass the wires through the core
Pass the free ends of the wire through the core. Place the core against the breadboard so that the LED and other components are inside it.
14. Wrap the core with wires
Use the wire coming from the collector of the transistor to “stitch” the toroid to the breadboard. To do this, pass the wire through the vias until you go around a full circle.
Many things that we often simply do not notice around us turn out to be in demand and very useful at a certain moment. One of these things is a regular flashlight. After all, if the lighting on the street or the electricity in the apartment is turned off, having a flashlight on hand will always correct the situation. This thing can be useful both on a camping trip or fishing, and in the garden.
Today there are a large number of different flashlights on sale, from small pocket flashlights to floodlights for illuminating large areas that are powered by solar energy. In any hardware store you can choose a lantern for your needs and according to your capabilities. In some cases, if it is not possible to purchase a ready-made lantern, you can make it yourself from scrap materials. This can save not only money, but also time when using a flashlight is urgently needed. Read on to learn how to make a simple lantern with your own hands.
LED flashlights have more advantages than conventional incandescent flashlights. Firstly, they last much longer, and secondly, they consume less energy. This means that the battery in the flashlight will last longer. Making a mini flashlight using a bright LED is quite simple. For this you will need:
- "Pocket" for batteries. An ideal option would be a battery pocket on an old motherboard.
- Battery (a regular tablet will be enough).
- A small button to turn on the flashlight.
- Super bright LED.
- Soldering iron, solder, glue, glue gun.
Work order:
- First you need to remove the battery pocket from the old motherboard. This is not a very difficult task for those who have ever held a soldering iron in their hand. Desoldering must be done carefully so as not to damage the contacts.
- Next, you need to solder the button to the positive pole of the pocket, and one LED leg is soldered to it. Its second leg is soldered to the negative pole. Thus, a simple electrical circuit is assembled that will close when the button is pressed. After assembling the circuit, you need to install the battery and check its functionality. If the LED lights up when the button is pressed, then assembly is completed correctly. To prevent the flashlight from breaking during operation and to prevent moisture from getting on the electrical solders, its top, except for the button, can be filled with hot glue.
- After the glue has cooled and hardened, the flashlight can be used.
Such a simple and cheap device is guaranteed to help in an emergency situation. All the parts necessary for its production can be easily found at home or bought on the radio market. Its undoubted advantage is its small overall dimensions. It is almost invisible in your pocket and does not take up much space in the glove compartment of your car.
Lantern made from a used gas-discharge lamp and lighter
Gas discharge lamps have become widespread and popular due to their efficiency. For the same luminous flux as a conventional incandescent lamp, the “housekeeper” spends almost 4 times less electricity. The most common reason for the failure of such a lamp is a breakdown of the controller board, which is located between the lamp itself and the base. In this case, the lamp itself can also be used to make a flashlight.
For this you will need:
- Old gas discharge lamp.
- Unnecessary electric lighter.
- Glue, hacksaw for metal.
Work order:
- The first step is to separate the lamp base from its body. To do this, use a hacksaw for metal. Then the lamp body is carefully opened and the controller is removed from it. When removing the controller, the wires that connect it to the bulb must not be torn off; they are carefully bitten off using wire cutters.
- Then the tip of the old electric lighter is sawed off. The lower part of the llama body is placed on its handle and glued with hot glue. Next, the lighter wires are connected to the lamp wires, after which its bulb is screwed to the body.
The result is a rather nice looking pen light that is battery powered at the press of a button. This product shines quite brightly, however, it produces scattered rather than focused light. With such a lantern it will be convenient to illuminate dark areas of the garage. If you install a button with a lock on it, the product can be used as a candle in the event of a lack of electricity.
When making a flashlight from a gas-discharge lamp, you must remember that the lower its power, the brighter it will shine. The fact is that the battery energy may not be enough for the normal glow of a large amount of mercury vapor, so a lamp of less power is preferable in this case.
DIY street lamp
It often happens that in an undeveloped area it is necessary to provide lighting for the area. This problem is especially important for those who are just starting to build a house in an “open field”.
To make a simple lantern for the garden with your own hands, you will need a few available materials:
- 2 liter jar with a screw-on sealed lid.
- Standard light bulb socket (E27 base).
- A piece of double insulated copper wire.
- A small piece of wire for making a hanger. You can use a decorative chain, then the lantern will look better in the garden.
- Electrician's tools, electrical tape (you can use heat shrink tubing).
Work order:
- First, a hole is carefully made in the lid for attaching the cartridge. To do this, you need to disassemble the cartridge and mark the diameter of the hole for the cartridge thread. After this, you need to cut a hole using a knife or scissors.
- Next, take the wire and solder it to the lamp base. The connection must be strong so that the wire does not tear away from the socket under the influence of wind.
- Then the cartridge is screwed to the lid of the jar. Now, if you close the jar, the light bulb will be reliably protected inside from moisture or mechanical impact. The wire is connected to the network through a switch.
- Next, you need to make a ring by which the lantern will be suspended. You can use copper wire for this. A small chain is attached to the ring, using which the new lantern is hung in the right place.
- For better insulation, the part of the cartridge that goes outside should be insulated. This can be done using electrical tape or polyethylene.
You can use steel baby food cans as a lantern by making thin holes in them using a nail or an awl. Many designers resort to this method to create a garland from similar cans, embossing interesting designs on them. This product looks simply amazing. However, it is worth noting that such a lantern cannot be used in conditions of high humidity, since if water gets on the lamp it can simply burst.
DIY solar lantern
Solar-powered lanterns have become quite popular in places where there are problems with connecting to the power grid. Thanks to the energy of the sun during the day, such a flashlight charges the battery located inside, which, when it gets dark, supplies energy to the LEDs that illuminate the area.
Making such a lantern for the garden with your own hands is quite difficult, because for a normal glow you need to solder a small circuit, and for this you need to have certain knowledge in electronics. Therefore, if you do not have the skills to assemble electrical circuits, it is better to buy such a flashlight in a store.
If you have such experience, you can make a small solar cell lamp yourself. For this you will need:
- Bright LED 3V, power 1 W.
- 3.7V battery and box for it.
- Solar cell voltage 5.5V, current 90 mA.
- Resistors with a resistance of 10 Ohm and 50 Kom.
- Transistor IRF 7832
- Diode.
- Housing for lamp. You can use a small plastic container.
Work order:
- First of all, one hole is made on the sides and in the lid of the container. Mounting bolts are installed on the sides, and an LED is mounted in the cover, which is secured with sealant. A small hole is made in the bottom of the box into which the wire from the solar cell is inserted.
- Next, the electrical circuit is assembled. All connections are carefully soldered and insulated with heat shrink tubing.
- The entire assembled circuit is placed in a box. All holes and the lid are sealed with sealant to prevent moisture from entering the structure.
Due to the bright LED, such a flashlight can illuminate a fairly large area. Thanks to the photocell, the device will turn on at a time when the intensity of natural light decreases. The role of the photocell will be performed by a solar battery, which is controlled by a transistor. When the current from it stops flowing into the network, the transistor will turn on power from the battery and supply it to the LED. When the solar battery is turned on, the transistor will direct energy not to the LED, but to the battery.
It is necessary to hang the lantern in such a way that the sun's rays hit its surface as much as possible. Such a flashlight, if used correctly, can last more than seven years.
To service and repair it, it is enough to remove the sealant layer and disassemble the structure. After repairing or replacing the battery, the case is reassembled and sealed. The low cost and ease of assembly of this design allows you to easily make several portable flashlights that will illuminate the area exactly where it is needed.
DIY solar lantern: video
Surely many of you from the physics course remember or have heard that you can get a little electricity from ordinary potatoes, and not only from them.
What is needed for this, and is it possible to light a low-power flashlight, an LED clock powered by 1-2V round batteries, or make a radio work in this way? Yes and no, let's take a closer look.
Where does electricity come from in potatoes?
To understand that voltage from potatoes is not a fiction, but a very real thing, just stick sharp probes from a multimeter into one single potato and you will immediately see several millivolts on the screen. 
If you complicate the design a little, for example, insert a copper electrode or a bronze coin into the tuber on one side, and something aluminum or galvanized on the other side, then the voltage level will increase significantly. 
Potato juice contains dissolved salts and acids, which are essentially a natural electrolyte.
By the way, you can use lemons, oranges, and apples for this with equal success. Thus, all these products can power not only people, but also electrical appliances. 
Inside such fruits and vegetables, due to oxidation, electrons will leak from the immersed anode (galvanized contact). And they will be attracted to another contact - copper.
However, do not be confused, electricity here is not generated directly from potatoes. It is well produced precisely thanks to chemical processes between three elements:
- zinc
- copper
- acid
And it is the zinc contact that serves as a consumable. All electrons flow away from it. Under certain conditions, even earthen soil can produce electricity. The main condition is its acidity. 
You stick two sticks (of course, made of zinc and copper) into the ground and measure the voltage. Sometimes the potential difference reaches 0.2V. With moist soil the result improves. 
This is the so-called earth battery.
Assembling a battery from potatoes
So, here's what you need to assemble a more or less capacitive battery:
Several pieces, since one will not be of much use.
The larger the cross-section, the better.
The nails will play the main role in generating electricity for the flashlight.
- galvanized - this is the negative contact (anode)
- copper-plated - this is a plus (cathode)
If you use simple nails instead of galvanized ones, you will lose up to 40-50% in voltage. But as an option, it will still work.
The same applies to using aluminum wire instead of nails. At the same time, increasing the distance between the electrodes in one potato does not play a special role.
Take copper wires (mono core) with a cross section of 1.5-2.5 mm2, 10-15 cm long. You strip them of insulation and tie them to a nail. 
It is best, of course, to solder, then the voltage loss will be much less. 
One copper nail on one side of the wire, and a galvanized nail on the other. 
In this case, different nails are stuck into each tuber, from different pairs of wires. That is, you must have one zinc contact and one copper contact plugged into each potato. 
Different tubers are connected to each other only through nails made of different materials - copper + zinc - copper + zinc, etc.
Voltage measurements
Let's say you have three potatoes, and you connected them together in the manner described above. To find out what voltage you get, use a multimeter. 
Switch it to the DC voltage measurement mode and connect the measuring probes to the conductors of the outermost potatoes, i.e. to the initial positive contact (copper) and the final negative contact (zinc).
Even with three medium-sized potatoes you can get almost 1.5 Volts.
If you reduce all transition resistances to the maximum, and for this:
- apply soldering to the contacts
then only 4 potatoes can produce up to 12 volts! 
If your cheap flashlight is powered by three AA batteries, then you will need about 5 volts to light it successfully. That is, when using conventional wires, you need at least three times more potatoes.
To do this, by the way, it is not necessary to look for additional tubers; it is enough to cut the existing ones into several parts with a knife. Then do the same procedure with the wires and studs. 
Insert one galvanized and one copper nail in succession into each cut tuber. As a result, it is quite possible to obtain a constant voltage of more than 5.5V.
Is it theoretically possible to get 5 volts from one single potato and at the same time ensure that the entire assembly is no larger in size than a AA battery? It is possible and very easy.
Cut small pieces of the core from the potato and place them between flat electrodes, such as coins made of different metals (bronze, zinc, aluminum). 
As a result, you should end up with something like a sandwich. Even one piece of such an assembly can produce up to 0.5V!
And if you put several of them together, then the required value of up to 5V can easily be obtained at the output. 
Current strength
It would seem that everything is achieved, the goal is achieved, and all that remains is to find a way to connect the wiring to the power contacts of the flashlight or LEDs. 
However, having gone through this procedure and assembled a rather weak structure from several potatoes, you will be very disappointed with the final result. 
Low-power LEDs will of course glow, after all, you still received voltage. However, the brightness level of their glow will be catastrophically dim. Why is this happening?
Because, unfortunately, such a galvanic element produces a negligibly low current. It will be so small that not even all multimeters can measure it.
Someone will think that since there is not enough current, they need to add more potatoes and everything will work out. Here's a video experiment using 400s! potatoes and connecting them to a 110-volt LED light bulb.
Of course, a significant increase in tubers will increase the operating voltage.
When tens or hundreds of potatoes are connected in series, the voltage will increase, but the most important thing will not be there - sufficient capacity to increase the current.
And this whole design will not be rationally suitable.
A practical way with boiled potatoes
But still, is there a simple way to increase the power of such a battery and reduce its size? Yes, I have. 
For example, if you use boiled rather than raw potatoes for this purpose, then the power of such a source of electricity increases several times!
To assemble a convenient compact design, use the case from an old C (R14) or D (R20) battery. 
Remove all contents inside (of course, except for the graphite rod). 
Instead of filling, fill the entire space with boiled potatoes. 
Then reassemble the battery structure in reverse order. 
The zinc part of the body of the old battery plays a significant role here.
The total area of the inner walls turns out to be much larger than just sticking cloves into raw potatoes.
Hence the greater power and efficiency.
One such power source will easily produce almost 1.5 volts, just like a small AA battery. 
But the most important thing for us is not volts, but milliamps. So, such a “cooked” modernization is capable of providing a current of up to 80 mA. 
These batteries can power a receiver or an electronic LED clock. 
Moreover, the entire assembly will work not for seconds, but for several minutes (up to ten). More batteries and potatoes, more battery life.
In the 21st century, it is difficult to surprise society with a simple flashlight. The device has become a part of life so reliably that it is difficult to imagine how life would be without it. Every thing breaks, breaks and stops working at the wrong time. We offer a couple of ways to make your own flashlight from what you have on hand.
The advantage of things made by hand is the cost, because everything is available on the farm.
Video training “How to make a flashlight with your own hands”
Low power flashlight
During physics lessons, the teacher showed how to make a mini-flashlight from a small light bulb, a AA battery and a piece of wire. To begin with, the wire is wound along the top edge around the lamp thread, the rest of the wire is wrapped with the long end down. The battery is connected with a wire to the light bulb so that the pole marked “+” and the base of the light bulb are connected. Do not forget that for reliable operation of the device you need to work on closing the circuit. To do this, near the free pole of the battery with the value “-” you need to make a couple of turns of wire.
To make the flashlight work, you will have to work hard on the correct placement of the wire with the light bulb at the end. The light range of such a device is short; there is no point in using it outdoors. The increase in power is achieved by adding a second battery and an aluminum reflector to the circuit.
LED flashlights
The device operating on LEDs is manufactured in two versions:
- Single diode. To create it you will need a Chinese lighter with a weak light. The Chinese are not known for their reliable products, so the LED provided by the manufacturer will have to be replaced with a bright white one. The light beam easily illuminates the next three meters and will become an indispensable thing for those who like to walk along the street in the dark.
- The second method is more complicated and involves the use of a battery, diode and resistor. The button is closed with the battery in the “-” pole, and the positive pole is closed with the lighter body. All that remains is to solder the resistor with a soldering iron exactly as in the diagram. To increase the power of the flashlight, you will have to install a resistor, otherwise the diode will not provide the required amount of light and will soon burn out.
Using this principle, you can make a powerful flashlight, but to do this you need to stock up on a significant number of LEDs, find the body of a non-working halogen lamp and a glue gun. There are hundreds of LED layout diagrams on the Internet, choose the one that suits you and transfer it to an aluminum sheet. Use a nail to pierce holes in the plate of such a size that the LEDs fit through them. For reliability, small parts are secured with superglue. A little secret: you need to place small light bulbs with the cathode towards the anode, so as not to create problems for yourself during soldering.
The LEDs should not be connected in groups of 4, after which a resistor is soldered in. As a result, positive poles are collected on the LED side, and negative poles are collected on the resistor side. The LED legs on each side are soldered together, and a copper wire is attached to the common poles. A disk with diodes is mounted into the reflector from the body of the halogen lamp and generously coated with glue. After complete drying, the wire of the positive pole is cut and attached to the battery; the same manipulations are carried out with the negative pole. Such a flashlight will serve the family for many years, and there will be no problems with its operation at all.
A flashlight is a necessary thing when traveling to nature or to the countryside. At night, on a personal plot or near a tent, only it will create a ray of light in the dark kingdom. But even in a city apartment, sometimes you just can’t do without it. As a rule, it is difficult to get something small that has rolled under a bed or sofa without a flashlight. And although nowadays there are devices that are multifunctional and can be a source of light, some of our readers will probably want to know how to make a flashlight with their own hands. How to make a small device from scrap items will be discussed below.
Classic shape
The most convenient design, which in principle has remained unchanged for flashlights for many years, is the design containing:
- cylindrical body with batteries of the same shape;
- reflector with a light bulb at one end of the housing;
- removable cover at the other end of the housing.
And this design can be obtained using unnecessary household items. If you make a lantern with your own hands, you will, of course, not have the beauty of shapes like an industrial design. But it will be functional and you will get a lot of positive emotions from a working homemade product.
So, the main problem, which at first glance is difficult to solve, is the reflector. But it just seems complicated. In fact, we are surrounded by many objects that can become preparations for a whole range of reflectors of different sizes. These are ordinary plastic bottles. Their inner surface near the neck is very close in shape to that of a reflector made at the factory. And the lid seems to be created for mounting an LED in it, which is the best light source today. It is brighter and more economical than a miniature light bulb.
Making a reflector
The fact that you may not be able to find a tube of suitable dimensions for making a body is not a problem. It can be glued together from individual parts. For example, from unnecessary disposable ballpoint pens. To spring the contacts, you can use a spiral, which is used for binding pages, and the contacts can be made from thin sheet metal, the raw material for which will be a tin can. Therefore, we start by choosing a plastic bottle of the desired size and selecting the remaining elements. The smaller the bottle, the stiffer and stronger the reflector will be. The easiest way to fasten parts during assembly is using construction sealant.
So, let's start making a flashlight with our own hands. Using a sharp knife, cut off the neck and parabolic part of the body from the bottle and trim the edges with scissors.
For effective reflection, we use foil in which chocolate bars are wrapped. If its size is not enough, you can cut a larger piece from a roll of foil intended for baking products. To keep the foil on the surface, apply a thin layer of sealant. Then we press and level the foil over it. If she wrinkles, it doesn't matter. The main thing is that there are no swellings and that it follows the shape of the base.
We press the foil with our fingers and, smoothing out the unevenness, form the most even surface possible. Using scissors, trim the edges of the foil flush with the plastic base. Along the contour of the neck we make a cutout with a knife for the LED, which will subsequently be installed in this place on the socket.
We make it from the bottom of a bottle cap, cutting off the threaded edges with a sharp knife and, if necessary, trimming them with scissors. Then, using an awl or the tip of a knife to make two holes in the socket, we thread the legs of the LED through them, pressing its base against it. To correctly install the LED lamp in the center of the cover, you must select the correct distance between the holes according to the location of the legs in the base of the LED.
We bend the LED leads to the sides until they touch the edges of the socket. We attach the conductors to them by twisting. If the twisting turns out to be unreliable due to the properties of the wire cores or for other reasons, soldering is used. After attaching the wires, the leads are folded along the socket. It is recommended to check the performance of the received part using the batteries used in the flashlight.
Then we cut out a contact pad for the battery from a sheet of tin, which rests on the socket with the LED. By twisting or soldering we connect the pad - terminal with a shorter wire. We attach the terminal to a spring, which in turn is attached to the socket. To fasten the elements we use sealant.
Then we glue the socket with the LED into the reflector.
Bottom and case with batteries
The part of the flashlight body opposite the reflector is also made from a part of a bottle with a neck. But only from the very neck with the lid. A terminal made of a sheet of tin is glued to its inner wall. A wire is also attached to it. This wire and the second wire from the LED will be used to control the flashlight. The terminal is in contact with the battery, being pressed by a cap that is screwed onto the neck.
Two main parts are ready. Now we need to make a case for the batteries. To do this, we use dry and therefore no longer needed felt-tip pens. We leave only the body, which we shorten in length and cut along the axis at the ends, making two protrusions for gluing. Before cutting, make marks with a marker, applying the body of the felt-tip pen to the parts to be glued.
Apply glue to the protrusions and glue them to the reflector and the back, respectively.
Then we cut out the switch parts from the tin sheet. We mount the wires to them and glue the parts to the body.
We insert batteries into the flashlight and use it. This, of course, is not a factory-made flashlight with a high-quality reflector and high beam. But it is made with your own hands, it is your own product, which gives good low-level lighting and gives great pleasure, and money cannot buy it. Now you have a clear idea of how easy it is to make a lantern yourself.
Ready flashlight and light from it