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Do-it-yourself high-voltage high-capacity capacitor. Low Inductance High Voltage Capacitor. We collect the ionistr with our own hands

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 you buy it in already ready-made will not be difficult, 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 convenient for 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 the with my own hands the 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 it is extremely important not to overdo it here, 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.

Requirements to reduce the size of radio components while increasing them technical specifications gave rise to a large number devices that are in widespread use 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 dry matter 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 there are different materials. 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 delimited by a material that would let through electricity, but did not miss the coal powder. 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 fit comfortably 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.

Good afternoon! Today I would like to show you how to make a Leyden jar, the simplest device in which you can store an electric charge.

Static electricity is just a lack or excess of electrons on the surface of an object.


One way to generate static electricity is the contact of two dissimilar objects. Many still remember the experiment with an ebonite stick from school. If you rub it with wool, then part of the electrons will run over to the stick and the wool will remain positively charged, and the stick, due to an excess of electrons, will be negatively charged and will be able to attract light objects.

In everyday life, such a situation occurs, for example, when combing hair with a comb. You can even hear the crackle of electrostatic discharges. By the way, did you know that such clicks have a voltage of several thousand volts? It turns out that with the help of an ordinary comb you can get just a huge voltage. Only now the charge that a comb can hold is very, very small. The charge from the comb can be accumulated elsewhere. For example, in the Leiden Bank. The Leyden jar is essentially the simplest capacitor (two conductors separated by an insulator.


Let's start manufacturing

materials
classical Leyden jar usually made from glass jar, but it has too thick walls, and the charge accumulates is not very large. Therefore we will use plastic jar with thin walls. As a conductor, we will use food foil, or foil from a chocolate bar.




Step 1
The jar needs to be covered with an even layer of foil about two-thirds in height, including the bottom itself. Avoid large wrinkles and tears.




Step 2
Now the same thing needs to be done from the inside, to the same height as the outer lining.


Step 3
In the center of the jar, attach a foil receiver that should touch the foil inside the jar. top must be taken out of the bank.


If you are too lazy to bother with gluing the inside of the can, then you can simply pour saline there exactly to the level to which the foil is pasted on the outside. (The receiver should touch the water with one end




So, now we have where to accumulate a charge from a comb. To do this, grasp the outer cover with one hand and run the loaded comb near the receiver with the other hand.


You can discharge the jar onto yourself by holding the lining with your hand and bringing your finger to the receiver. And you can also make such a cool spark gap from a piece of foil, which will give a more even and beautiful spark.


On a note: a breakdown of 1 mm of air requires a voltage of one thousand volts. By the way, air humidity critically affects the length of the spark (the drier it is in your apartment, the longer the spark will be).

How to make a capacitor?




An inventor lives in the soul of each of us, and therefore amateur radio is a fairly popular hobby. Self-manufacturing radio components - one of the most interesting components of this hobby. In this article we will talk about how to make a capacitor with your own hands at home.

materials

To make a capacitor, we need:

  • foil,
  • iron,
  • papyrus paper,
  • paraffin,
  • lighter.

The foil does not need additional preparation, but with the help of the last three components we have to make waxed paper.

Manufacturing

So, the materials are prepared, let's get to work:

  1. We heat the paraffin and carefully process the papyrus paper.
  2. We fold it into an "accordion", the width of each section of which is about 30 mm. The number of harmonica layers determines the capacitance of the capacitor, each layer corresponds to approximately 100 pF.
  3. In each section we put a piece of foil with an area of ​​​​30 by 45 mm.
  4. We fold the accordion and iron it with a warm iron.
  5. Everything, the capacitor is ready! The pieces of foil peeking out are the connecting contacts of our capacitor, through which it can be connected to the circuit.

We got the simplest household capacitor, while it is worth noting that the thicker and better the foil, the more high-voltage it will be. However, we draw your attention to the fact that it is better not to try to make a capacitor at home that can withstand more than 50 kV. "Amateur professionals" advise, if you want to get close to this value, use lamination bags as a dielectric, but you will need a laminator to heat them.

If you are planning to build a laser, an accelerating tube, an electromagnetic interference generator, or anything else of that kind, then sooner or later you will be faced with the need to use a low-inductance high voltage capacitor, capable of developing the Gigawatts of power you need.
In principle, you can try to get by using a purchased capacitor and something close to what you need is even commercially available. These are ceramic capacitors of the KVI-3, K15-4 type, a number of brands from Murata and TDK, and of course the beast Maxwell 37661 (the latter, however, is of an oil type)

The use of purchased capacitors, however, has its drawbacks.

  1. They are expensive.
  2. They are inaccessible (the Internet, of course, has connected people, but dragging parts from the other end the globe somewhat annoying)
  3. Well, and most importantly, of course: they still will not provide the record parameters you require. (When it comes to a discharge in tens and even a few nanoseconds to power a nitrogen laser or obtain a beam of runaway electrons from a non-evacuated accelerating tube, not a single Maxwell can help you)

According to this guide, we will learn how to make a homemade low-inductance high-voltage
capacitor on the example of a board intended for use as a driver
lamp dye laser. However, the principle is general and with its
using you will be able to build capacitors in particular (but not limited to)
even to power nitrogen lasers.

I. RESOURCES


II. ASSEMBLY

When designing a device that requires a low inductance power supply, one should think about the design as a whole, and not separately about capacitors, separately about (for example) a laser head, etc. Otherwise, current-carrying bars will negate all the advantages of a low-inductance capacitor design. Usually capacitors are organic integral part such devices, and that is why the dye laser driver board will serve as an example.
Blessed is that do-it-yourselfer around whom sheets of fiberglass and plexiglass are lying around. I have to use store-bought kitchen cutting boards.
Take a piece of plastic and cut it to the size of the future circuit.

The idea of ​​the scheme is primitive. These are two capacitors, storage and sharpening, connected through a spark gap according to a circuit with resonant charging. We will not deal with the operation of the circuit in detail here, our task here is to focus on assembling capacitors.

Having decided on the dimensions of future capacitors, cut pieces of an aluminum corner according to the dimensions of future contactors. Carefully process the corners in accordance with all the rules of high-voltage technology (round off all corners and blunt all points).

Fix the leads of future capacitors on the resulting "printed circuit board".

Mount those parts of the circuit that, if not assembled now, may later interfere with the assembly of the capacitors. In our case, these are connecting buses and a spark gap.

note that the low inductance when installing the arrester is sacrificed for ease of adjustment. In this case, this is justified, since the intrinsic inductance of the (long and thin) lamp is noticeably greater than the inductance of the arrester circuit, and besides, the lamp, according to all the laws of a black body, will not shine faster than sigma * T ^ 4, no matter how fast chain there was no food. You can shorten only the front, but not the entire impulse. On the other hand, when designing, for example, a nitrogen laser, you will no longer mount a spark gap so freely.

The next step is to cut the foil and possibly the laminate packages (unless the size of the capacitor calls for a full package format, as is the case for the storage capacitor on the board in question.)

Although the lamination is ideally airtight and edge flashing must be avoided, it is not recommended to make beads (dimension d in the figure) less than 5 mm for every 10 kV of operating voltage.
Edges of 15 mm in size for every 10 kV of voltage provide more or less stable operation even without sealing.
The size of the pins (size D in the figure) should be chosen equal to the expected thickness of the foot of the future capacitor with some margin. The corners of the foil, of course, should be rounded.
Let's start with the peak capacitor. This is how the blanks and the finished, laminated lining look like:

For the peak capacitor, a 200 µm thick laminate was taken, since a voltage surge of 30 kV is expected here due to "resonant" charging. Laminate the required number of covers (in our case, 20 pcs.). Fold them in a pile (pins alternately in different directions). At the resulting stack, bend the leads (if necessary, cut off the excess foil), place the stack in the nest formed by the angle contactors on the board and press the top cover.

Fetishists will fix the top cover with neat bolts, but you can simply tape it with tape. The peak capacitor is ready.

The assembly of a storage capacitor is no fundamentally different.
Less scissor work as full A4 size is used. The laminate here is 100 µm thick because the plan is to use a charging voltage of 12 kV.
In the same way, we collect in a pile, bend the conclusions and press the lid:

A kitchen board with a cut handle looks, of course, malicious, but does not violate functionality. I hope that you will have fewer problems with resources. And one more thing: if you decide to use pieces of wood as a base and cover, they will have to be seriously prepared. The first is to dry thoroughly (preferably at elevated temperature). And the second - hermetically lacquered. Urethane or vinyl varnish.
The point here is not electrical strength and not leaks. The fact is that when the humidity changes, the pieces of wood will bend. Firstly, this will disrupt the quality of the contact and lengthen the discharge time of the capacitors. Secondly, if, as here, a laser is supposed to be mounted on top of this board, it will also be bent with all the ensuing consequences.

When bending the leads, do not forget to lay an additional layer of insulation. And then in fact: the plates are separated from each other by two dielectric layers, and the leads from the plates of opposite polarity are separated by only one.
Let's see what we got. Let's use a multimeter with a built-in capacitance meter.
Here is what the storage capacitor shows.

And here is what the peak capacitor shows.

That's all. Capacitors are ready, the topic of the guide is over.
However, I'm probably looking forward to trying them out. We complete the missing part of the circuit, install the lamp, connect it to the power source.
Here's what it looks like.

Here is an oscillogram of the current, taken with a small ring of wire directly connected to the oscilloscope and located near the circuit that feeds the lamp. True, instead of a lamp, the circuit was loaded on a shunt.

And here is an oscillogram of a lamp flash, taken with an FD-255 photodiode aimed at the nearest wall. Scattered light is enough. It's even more correct to say "more than."

You can scold badly turned out capacitors for a long time and look for the reason why the discharge lasts more than 5 μs ... In fact, the flash lamp dumps a bunch of megawatts and even the light scattered from the walls drives the photodiode into deep saturation. Let's take the photodiode away. Here is an oscillogram taken from 5 meters, when the photodiode does not look exactly at the light bulb, but slightly away from it.

The rise time is difficult to determine precisely due to interference, but it can be seen that it is on the order of 100 ns and is in good agreement with the duration of the current half-cycle.
The remaining tail in the light pulse is the glow of a slowly cooling plasma. The total duration is under 1 µs.
Will this be enough for a laser on a karasitel? This is a separate issue. In general, such an impulse is usually more than enough, but it all depends on the dye (how pure and good it is), on the cuvette, illuminator, resonator, etc. If I manage to get generation on one of the commercially available fluorescent markers, then there will be a separate guide on a homemade dye laser.

(PS) I had to add another 30 nF to the main storage capacitor and it really was enough. The pipe, the photo of which can be found right there in the "Photos" section, worked even better than from the two-maxwell GIN.

In general, a discharge time of 100 ns is by no means the limit for the described technology for creating capacitors. Here is a photo of a capacitor with which an air pumping nitrogen laser works stably in the superradiance mode:

Its discharge time is already beyond the capabilities of my oscilloscope, however, the fact that the nitrogen tank with this capacitor effectively generates already at 100 mm Hg. allows the discharge time to be estimated at 20 ns or less.

III. INSTEAD OF CONCLUSION. SECURITY

To say that such a capacitor is dangerous is to say nothing. An electric shock from such a container is as deadly as a KAMAZ flying at you at a speed of 160 km/h. Treat this capacitor with the same respect as a weapon or explosives. When working with such capacitors, use all possible safety measures and, in particular, remote switching on and off.
It is simply impossible to predict all dangerous situations and give recommendations on how not to get into them. Be careful and think with your head. Do you know when a sapper's career ends? When he stops being afraid. It is at the very moment when he becomes "on you" with explosives that he blows his head off.
On the other hand, millions of people drive on the roads with KAMAZ vehicles and thousands of sappers go to work and stay alive. As long as you are careful and think with your head, everything will be all right.

Tank capacitor

This type of capacitor got its name from the similarity of the shape of the plates with the T-shirt package.
The inductance of this capacitor is greater than that of the conder described above or the candy one, but it is quite suitable for use in CO2 or GIN. With difficulty it starts the dye and is not suitable for nitrogen.

The materials you will need are the same as in the guide above: mylar film (or lamination bags), aluminum foil and adhesive tape / electrical tape.

The diagram below shows the dimensions of the main gaps.


L - dielectric length
D - dielectric width
R is the outer radius of the capacitor

The gaps from the edges of the dielectric are 15mm. On the side where the contact strips of the plates come out, there is an indent of 50 mm. These offsets are made as small as possible for the maximum capacitance for a given L and D of the dielectric. Please note that these clearances are selected for 10kV. (I doubt it makes sense to make this type of capacitor for higher voltages, so I won't write formulas here to recalculate offsets and gaps for other voltages)

The distance between the leads of the plates is 30mm. This gap is also taken as the minimum possible for 10 kV. Increasing this gap will make the leads too narrow - increasing the inductance of the capacitor.

Manufacturing

The tank condenser is ready. You can install it with your laser, GIN or other high-voltage device.