This element is rightfully considered to be super universal, since it can be simultaneously used in the manufacture and repair of a wide variety of devices. And even if it is not difficult to purchase it in a ready-made form, many amateur craftsmen are happy to experiment, trying or even successfully making a capacitor with their own hands. Everything that is needed to create a home-made capacitor is described in detail above and, in principle, there should not be any difficulties with any of the necessary elements, since they can be found on the farm or, at worst, on free sale. The only exception, perhaps, can be paraffin paper, which is usually made independently using materials such as paraffin, papyrus and a disposable lighter (alternatively, you can use any other safe source of an open flame).
So, in order to process the paper properly, you should carefully heat the paraffin with a fire and walk its softened part over the entire surface of the papyrus on both sides. After the work is completed, and the material has properly set, the resulting paraffin paper must be folded with an accordion (meaning transverse advancement). The technique is common, but it involves maintaining a certain step (every three centimeters) and in order to make the fold line as accurate as possible, it is advisable to outline the first strip with a simple pencil even before initialing. You can continue in the same vein, completely drawing out the entire sheet, or you can act, focusing solely on the first segment (as it suits you). As for the number of layers required, this indicator is determined solely by the capacity of the future product.
At this stage, the formed accordion should be put aside for a while in order to proceed with the preparation of rectangular pieces of foil, the dimensions of which should correspond in this case to the data 3 by 4.5 centimeters. These blanks are necessary to make the metal layer of the capacitor, therefore, at the end of the above work, the foil is inserted into all layers of the accordion, making sure that it fits evenly, after which they proceed to ironing the folded blank with a conventional iron. Paraffin and foil should do their job, providing a strong bond between themselves (other methods for soldering a capacitor at home are not practiced), after which the capacitor can be considered absolutely ready. As for the foil elements protruding beyond the former accordion, it should not give cause for concern, since they play the role of connecting contacts.
It is with the help of these small fragments that a self-made capacitor can be fully used by connecting it to an electrical circuit. Naturally, we are talking about a primitive device, and in order to somehow increase its performance, it is necessary to use a higher quality foil with a high density, although here it is extremely important not to overdo it, since there are certain limits on the voltage used for crafts for adults of this kind. So, for example, it is better not to experiment, trying to make a capacitor with your own hands that can accept too high a voltage (more than 50 Volts), although some "homemade" ones manage to get around this side of the issue by using lamination bags instead of standard dielectrics, as well as a laminator for safe soldering.
There are several other methods for making a homemade capacitor, and one of them involves working with a higher voltage. The famous technique "Glass" can be attributed to it, the name of which came from the improvised tool used - a faceted glass. This element is necessary for covering with foil from the inside and outside, and this should be done in such a way that the fragments of the material used do not touch each other. The design itself in an already "assembled" form necessarily provides for the presence of supplies, after which it can be considered completely ready for use for its intended purpose. At the same time, during its inclusion in the circuit, it is necessary to carefully observe all the necessary safety measures in order to avoid possible negative consequences.
Alternatively, you can try to make a more advanced design with your own hands, using such improvised means as glass plates of the same size, the same good old high-density foil and epoxy resins designed to securely connect the listed materials to each other. The undoubted advantage of such a home-made capacitor is that it is able to carry out better work, as they say, "without breakdown." However, as you know, a barrel of honey usually does not do without a fly in the ointment, and in this case it directly relates to one significant drawback of this invention, which lies in its more than impressive dimensions, which makes keeping such a "colossus" at home not very convenient and rational.
Fans of different high-voltage experiments often face the problem when it is necessary to use high-voltage capacitors. As a rule, such capacitors are very difficult to find, and if you succeed, you will have to pay a lot of money for them, which not everyone can afford. In addition, the policy of our site simply will not allow you to spend money on buying something that you can make yourself without leaving your home.
As you may have guessed, we decided to devote this material to the assembly of a high-voltage capacitor, which is also devoted to the author's video, which we invite you to watch before starting work.
What do we need:
- knife;
- what we will use as a dielectric;
- food foil;
- a device for measuring capacitance.
We note right away that the author of a home-made capacitor uses the most common self-adhesive wallpaper as a dielectric. As for the capacitance measuring device, its use is not necessary, since this device is intended only so that at the end you can find out what happened in the end. Everything is clear with the materials, you can start assembling a homemade capacitor.
First of all, we cut off two pieces from self-adhesive wallpaper. You need about half a meter, but it is desirable that one strip is slightly longer than the other.
The resulting sheet of foil mode is exactly two parts in length.
The next thing we put on a flat surface is one piece of wallpaper, on which we carefully place one piece of food foil. The foil must be laid so that a gap of about a centimeter is obtained along three edges. On the fourth side, the foil will stick out, which is quite normal at this stage.
Put the second sheet of wallpaper on top.
We put a second sheet of foil on it. Only this time we make it so that the foil protrudes from the side opposite to the previous step. That is, if the author has the first piece protruding from below, then this time it should protrude from above. Separately, it should be noted that the sheets of foil should not touch each other.
Now we remove the substrate from one edge and glue our capacitor.
If you are an avid radio amateur and love to build radios, then you might have noticed that suppliers of electronic components have somewhat reduced the range of tuning capacitors of variable capacitance. There was a time when almost every radio receiver had at least one tuning capacitor, but now with the advent of the varicap and frequency synthesizer, such an antenna circuit tuning capacitor is a rarity. They're still being made, but they're not cheap, and they won't show up in your component box as quickly as they used to.
Fortunately, the variable capacitor is a remarkably simple device. And you can make it yourself, at least a capacitor with a capacity of several tens of picofarads is assembled from improvised materials.
To assemble a homemade capacitor, you will need a bolt, a couple of nuts, a piece of coated copper wire (length 30 cm, caliber AWG22, i.e. 0.64 mm diameter) and a small piece of textolite.
First, screw the nuts onto the bolt and apply tin to one of the faces of each nut, then solder this bolt with nuts to a piece of copper textolite, as shown in the figures below.
It is desirable to take a bolt with a length of 16 mm. If one was not at hand, then you can take a longer one, but you will have to cut it to length. Now wrap the edge of the bolt with copper wire. Make 12 rings, after the twelfth turn, cut off the excess ends of the wire, leaving about 12-15 mm on each side.
The figure below shows the penultimate step. At this stage, you need to make a small plastic gasket and place it between the nuts. This is necessary to securely fix the structure when the bolt is rotated during the setting of such a homemade capacitor. A piece of such plastic can be from anything and any type of plastic. In this case, a piece of plastic pipe was used.
The final step is simply to bend the outer end of the coil wire towards the inner end, then cut off the excess. Next, take a knife or other blade and remove the enamel from the end of the wire. In the end, take the cut piece of wire, strip it all and solder it to a piece of textolite between two nuts. Make sure that both ends of the coil are about 12-15 mm long. Now you can connect your homemade variable tuning capacitor with these ends to your radio.
The electrical capacitance of the globe, as is known from the course of physics, is approximately 700 microfarads. An ordinary capacitor of such a capacity can be compared in weight and volume with a brick. But there are capacitors with the electrical capacity of the globe, equal in size to a grain of sand - supercapacitors.
Such devices appeared relatively recently, about twenty years ago. They are called differently: ionistors, ionixes or simply supercapacitors.
Do not think that they are available only to some high-flying aerospace firms. Today you can buy a coin-sized ionistor in the store with a capacity of one farad, which is 1500 times the capacity of the globe and close to the capacity of the largest planet in the solar system - Jupiter.
Any capacitor stores energy. To understand how large or small the energy stored in the ionistor is, it is important to compare it with something. Here is a somewhat unusual, but visual way.
The energy of an ordinary capacitor is enough for it to jump about a meter and a half. A tiny ionistor of type 58-9V, having a mass of 0.5 g, charged with a voltage of 1 V, could jump to a height of 293 m!
Sometimes it is thought that ionistors can replace any battery. Journalists depicted the world of the future with silent electric vehicles powered by supercapacitors. But so far this is far from it. An ionistor weighing one kg is capable of accumulating 3000 J of energy, and the worst lead battery - 86,400 J - 28 times more. However, when delivering high power in a short time, the battery quickly deteriorates, and it is only half discharged. The ionistor, on the other hand, repeatedly and without any harm to itself gives off any power, if only the connecting wires could withstand them. In addition, the ionistor can be charged in seconds, and the battery usually takes hours to do this.
This determines the scope of the ionistor. It is good as a power source for devices that consume high power for a short time, but quite often: electronic equipment, flashlights, car starters, electric jackhammers. The ionistor can also have military applications as a power source for electromagnetic weapons. And in combination with a small power plant, the ionistor allows you to create cars with electric wheels and fuel consumption of 1-2 liters per 100 km.
Ionistors for a wide variety of capacities and operating voltages are on sale, but they are expensive. So if you have time and interest, you can try to make an ionistor yourself. But before giving specific advice, a little theory.
From electrochemistry it is known: when a metal is immersed in water, a so-called double electric layer is formed on its surface, consisting of opposite electric charges - ions and electrons. Between them there are forces of mutual attraction, but the charges cannot approach each other. This is hindered by the attractive forces of water and metal molecules. At its core, the electrical double layer is nothing more than a capacitor. The charges concentrated on its surface act as plates. The distance between them is very small. And, as you know, the capacitance of a capacitor increases with a decrease in the distance between its plates. Therefore, for example, the capacitance of an ordinary steel spoke immersed in water reaches several mF.
In essence, an ionistor consists of two electrodes with a very large area immersed in the electrolyte, on the surface of which, under the action of an applied voltage, a double electric layer is formed. True, using ordinary flat plates, it would be possible to obtain a capacitance of only a few tens of mF. To obtain large capacitances inherent in ionistors, they use electrodes made of porous materials having a large pore surface with small external dimensions.
For this role, spongy metals from titanium to platinum were tried at one time. However, incomparably the best was ... ordinary activated carbon. This is charcoal, which after special treatment becomes porous. The surface area of the pores of 1 cm3 of such coal reaches thousands of square meters, and the capacitance of the electrical double layer on them is ten farads!
Self-made ionistor Figure 1 shows the design of the ionistor. It consists of two metal plates tightly pressed against the "stuffing" of activated carbon. Coal is stacked in two layers, between which a thin separating layer of a substance that does not conduct electrons is laid. All this is impregnated with electrolyte.
When the ionistor is charged in one half of it, a double electric layer is formed on the pores of the coal with electrons on the surface, in the other half - with positive ions. After charging, ions and electrons begin to flow towards each other. When they meet, neutral metal atoms are formed, and the accumulated charge decreases and may eventually disappear altogether.
To prevent this, a separating layer is introduced between the layers of activated carbon. It can be made up of various thin plastic films, paper, and even cotton.
In amateur ionistors, the electrolyte is a 25% sodium chloride solution or a 27% KOH solution. (At lower concentrations, a layer of negative ions will not form on the positive electrode.)
Copper plates with wires pre-soldered to them are used as electrodes. Their working surfaces should be cleaned of oxides. In this case, it is advisable to use a coarse-grained skin that leaves scratches. These scratches will improve the adhesion of the coal to the copper. For good adhesion, the plates must be degreased. The degreasing of the plates is carried out in two stages. First, they are washed with soap, and then rubbed with toothpowder and washed off with a stream of water. After that, you should not touch them with your fingers.
Activated charcoal, bought at a pharmacy, is ground in a mortar and mixed with electrolyte until a thick paste is obtained, which is smeared with carefully defatted plates.
During the first test, the plates with a paper gasket are placed one on top of the other, after which we will try to charge it. But there is a subtlety here. At a voltage of more than 1 V, the release of gases H2, O2 begins. They destroy carbon electrodes and do not allow our device to work in the ionistor capacitor mode.
Therefore, we must charge it from a source with a voltage of no higher than 1 V. (This is the voltage for each pair of plates that is recommended for the operation of industrial ionistors.)
Details for the curious
At a voltage of more than 1.2 V, the ionistor turns into a gas battery. This is an interesting device, also consisting of activated carbon and two electrodes. But structurally, it is made differently (see Fig. 2). Usually, two carbon rods are taken from an old galvanic cell and gauze bags of activated carbon are tied around them. KOH solution is used as electrolyte. (Salt solution should not be used, as chlorine is released when it decomposes.)
The energy intensity of the gas accumulator reaches 36,000 J/kg, or 10 Wh/kg. This is 10 times more than that of an ionistor, but 2.5 times less than that of a conventional lead battery. However, a gas accumulator is not just a battery, but a very peculiar fuel cell. When it is charged, gases are released on the electrodes - oxygen and hydrogen. They "settle" on the surface of activated carbon. When a load current appears, they are connected to form water and electric current. This process, however, without a catalyst is very slow. And, as it turned out, only platinum can be a catalyst ... Therefore, unlike an ionistor, a gas accumulator cannot give high currents.
However, the Moscow inventor A.G. Presnyakov (http://chemfiles.narod.r u/hit/gas_akk.htm) successfully used a gas accumulator to start a truck engine. Its solid weight - almost three times more than usual - in this case turned out to be tolerable. But the low cost and the absence of such harmful materials as acid and lead seemed extremely attractive.
A gas accumulator of the simplest design turned out to be prone to complete self-discharge in 4-6 hours. This put an end to the experiments. Who needs a car that can't be started after a night of parking?
And yet, “big technology” has not forgotten about gas batteries. Powerful, light and reliable, they are on some satellites. The process in them takes place under a pressure of about 100 atm, and spongy nickel is used as a gas absorber, which under such conditions works as a catalyst. The entire device is housed in an ultra-light carbon fiber balloon. The result was batteries with an energy capacity of almost 4 times higher than that of lead batteries. An electric car could travel about 600 km on them. But, unfortunately, while they are very expensive.
The requirement to reduce the size of radio components while increasing their technical characteristics caused the emergence of a large number of devices that are used everywhere today. This fully affected the capacitors. The so-called ionisters or supercapacitors are elements with a large capacity (the range of this indicator is quite wide from 0.01 to 30 farads) with a charging voltage of 3 to 30 volts. However, their size is very small. And since the subject of our conversation is a do-it-yourself ionistr, it is necessary first of all to deal with the element itself, that is, what it is.
Design features of the ionistr
In fact, this is an ordinary capacitor with a large capacitance. But ionistors have high resistance, because the element is based on an electrolyte. This is the first. The second is a small charging voltage. The thing is that in this supercapacitor, the plates are located very close to each other. This is precisely the reason for the reduced voltage, but it is for this reason that the capacitance of the capacitor increases.
Factory ionistry are made of different materials. Linings are usually made of foil, which delimits the dry substance of the separating action. For example, activated carbon (for large plates), metal oxides, polymeric substances that have high electrical conductivity.
We collect the ionistr with our own hands
Assembling an ionistr with your own hands is not the easiest thing, but you can still do it at home. There are several designs where different materials are present. We offer one of them. For this you will need:
- metal coffee jar (50 g);
- activated carbon, which is sold in pharmacies, can be replaced with crushed carbon electrodes;
- two circles of copper plate;
- cotton wool
The first step is to prepare the electrolyte. To do this, you first need to grind activated carbon into powder. Then make a saline solution, for which you need to add 25 g of salt to 100 g of water, and mix it all well. Further, activated carbon powder is gradually added to the solution. Its quantity determines the consistency of the electrolyte, it should be as dense as putty.
After that, the finished electrolyte is applied to copper circles (on one side). Please note that the thicker the electrolyte layer, the greater the capacity of the ionistr. And one more thing, the thickness of the applied electrolyte on two circles should be the same. So, the electrodes are ready, now they need to be demarcated with a material that would pass an electric current, but not let the coal powder through. For this, ordinary cotton wool is used, although there are many options here. The thickness of the cotton layer determines the diameter of the metal coffee jar, that is, this entire electrode structure should easily fit into it. Hence, in principle, it is necessary to select the dimensions of the electrodes themselves (copper circles).
It remains only to connect the electrodes themselves to the terminals. Everything, a do-it-yourself ionistr, and even at home, is ready. This design does not have a very large capacity - no higher than 0.3 farads, and the charging voltage is only one volt, but this is a real ionistr. 
Conclusion on the topic
What else can be said in addition about this element. If we compare it, for example, with a nickel-metal hydride type battery, then the ionistr can easily hold a supply of electricity up to 10% of the battery power. In addition, the voltage drop in it occurs linearly, and not abruptly. But the level of charge of the element depends on its technological purpose.
