Homemade hand warmer with your own hands. Pocket Reactor - Homemade Catalytic Hand Warmer Step by Step Manufacturing Plan
Hello everyone. Fishermen, hunters, tourists, in general, everyone who reads this article.
Today I will share my idea - how you can make a hand warmer from a SIMPLE PENCIL.
Such a heating pad can provide very good heating, with a relatively low consumption. (SPECIFICALLY, what I got will be lower).
THIS ARTICLE IS NOT A INSTRUCTIONS FOR ASSEMBLING HAND WARMERS, BUT ONLY A DEMONSTRATION OF MY IDEA, ITS IMPLEMENTATION AND WHAT HAS GOT FROM THIS. REMEMBER YOUR SAFETY IS IN YOUR HANDS.
I took the most ordinary graphite pencil as a basis for such a heating pad (here you can experiment a little with the length and thickness of the rod).
The most common one came up for 8-15 rubles in wooden clothes (it can be more expensive, there is a denser wood, better heat transfer + -3-5 degrees difference) with the same consumption.
As it turned out, plastic (ECO) -that bend-are not suitable because they do not conduct current.
Now I decided on a pencil-vibrated the length and the required heating.
grinded it to the desired diameter (cleaned off the paint - reduces the heat dissipation) - made additional cuts.
Here it was revealed that the neck itself (without a shell) - heats up very strongly, usually + 15C to the fact that in the shell, but without it it becomes very vulnerable (brittle).
I tried different variants protection of the rod .. from simple heat shrinkage to various tubes. Moroki is a little useless. I decided to leave it in its native shell, I just grinded it off as much as possible and made cuts. ON PHOTO pencils with different shells (loose and hard wood).
The next step was to connect the USB WIRE - (it was not so simple here - do not solder .. do not squeeze properly).
I tried two of these options for connecting the wire to graphite.
I liked BOTH options (in my own way). If you know your a good option connection to graphite-write-it will be interesting.
After connecting the wire, everything was neatly packed with heat shrinkage.
The result is such a hot-water bottle from POVERBANK.
At the time of this article's creation, it worked for more than 150 hours (on average, 3-6 hours, depending on the power bank). The heating pad works clearly-the POWER BANKS are still intact.
The heating pad that is in the photo and in the video heats up to 70C AT 0.7-0.8A - to be honest, this is a lot for the hands (even at an ambient temperature of 0-2C, it gave out 50 + 55C, too much for me (but this is a test version)
The maximum that I managed to squeeze out with a good ratio of + 45 + 50C OR + 30 + 35 was measured at 0-2 (for me the most comfortable temperature). THIS is at 5V-0.5-0.6A.
The length of the wire is already a matter of convenience (the main thing is more powerful, so that it would pull such a strap)
The shell is also a matter of aesthetics and convenience, the main thing is that it has good thermal conductivity.
Well, in principle, all dear readers, the heating pad works and heats up.
Winter came imperceptibly, I felt it when on the way to the store my hands were very cold. Of course I know about gloves, but they do not warm, but only keep the warmth of our hands. So I decided to whip up a mini heating pad especially for my precious hands. There are a lot of hot water bottles of this kind in the markets, but still he wanted to make his own.
On sale there are heating pads with a combustible mixture inside, these are camping heating pads with a long reserve on the principle of catalytic combustion. There are also electric heating pads with a built-in battery and heating element.
A long time ago I bought several power banks with a metal case, and a heating pad was assembled on the basis of this case.
My heating pad will be electric.
On aliexpress, I bought an infrared heating element used as a heater for a warm floor; they also wrap water pipes with it so that the water in the latter does not freeze. Well, in general, such a heater has a lot of applications.
The heater consists of two parts - a fiber resistive material that is actually heated, and a heat-resistant flexible insulation.
Such heaters are powered from the mains, 10 meters of such a wire consumes about 160 watts when powered from a 220 volt network. It was this material that I decided to use in my heating pad.
Empirically picked up optimal power heating element, for this a nichrome heater was used. I wound the wire on the aluminum frame of the power bank and selected the length so that when powered from 12 and volts, the case heats up to 50 degrees in a maximum of 20-30 seconds, as a result, I found out that this requires a heater with a power of about 6 watts.
Knowing some initial data and Ohm's law, you can easily calculate the required length of the heater, but you need to take into account that as the heater heats up, the resistance of the heater will increase, therefore the power will decrease, the length and resistance are not so important for my case, since everyone will calculate the heater individually depending on supply voltage and heater length.
The heater will be powered by just one standard lithium can 18650 , but not directly, but through a step-up converter, it is possible without it, but in order to get the required power from 3.7 Volts, you need to shorten the wire length and connect several in parallel. To avoid the collective farm, I decided to use the converter, in this case, the heater will be solid and will stretch along the entire length of the sleeve, thereby ensuring uniform heating.
In the heating pad, the battery must be protected, otherwise it may fail due to a deep discharge.
I kept some distance between the turns of the heater, having received something like grooves for fingers, so that the heating pad fits perfectly in the hand.
A cheap MT3608 scarf is ideal as a boost converter, we supply 3.7 Volts to the board input and turn the trimmer resistor at the module output to 12 Volts. My case turned out to be too small and the converter board simply did not fit, but did not want to change the case, in the end I decided to modify the inverter shawl with wire cutters, and that's what happened.
The size has decreased by two and a half times.
We will make measurements of power and operating time. We supply a voltage of 3.7 volts to the input of the inverter, simulating a battery, connect a heater and a wattmeter to the output of the inverter.
The consumption from the battery is slightly less than two amperes, of which about 100mA is consumed by the wattmeter itself, which is a little more than 7 watts at the input, and at the output we have 4.5-5 watts, the efficiency is about 70%. Naturally, without an inverter, there would be less losses. But even with all this, a 2200mAh battery is enough for a little more than an hour continuous operation of the heating pad, and if this is not enough, you can take a 3400mA / h battery.
Heat-resistant scotch tape is wound on the aluminum case of the power bank, in principle it is not needed, initially it was used for thermal insulation of the case. This is necessary so that the battery does not overheat, but later tests showed that most of the heat will be directly transferred to the hand, and the temperature inside the case is not critical.
Despite the stripped-down converter board, I had to lengthen the case, since I completely forgot that at the beginning I planned to shove the charging system here from the USB.
The heater is turned on with a button without fixing.
The button is located directly under the thumb, it is convenient, no matter which hand you have a heating pad in. The button here is not easy to use, since the heating pad will mostly be in your pocket, there is no guarantee that you will not leave it on, and there will be no such problems with the button, let go and everything turned off.
The charging circuit is based on TP4056, nothing new. This fee also had to be reduced.
Well, now we turn on the heating pad and measure the temperature.
I think the result is excellent, if you hold the heating pad in your hand, some of the heat will be removed by the hand itself. and if it is too hot, the temperature can be reduced by decreasing the output voltage of the inverter, it is not for nothing that I made a hole for adjustment.
Hello, my little art lovers!
Today I will tell you how to make at home SALT HEATER.
Yes, yes, I was not mistaken. Exactly salt heating pad, which is sold in pharmacies and which is described in this article nepropadu.ru/blog/equipment/978.html
I was always interested in the process of how this heating pad works, until I took this issue seriously. And it turns out that everything that is needed to make it is in our home. You don't need to buy anything specifically, if only the container itself. I myself am thinking of using the bags for the saline solution used in droppers as a container.
So let's get started.
I warn you right away that I am not a chemist, even very far away, so if real chemists notice any inaccuracies in my descriptions, please correct them. The whole point of what we're going to do is get sodium acetate. And for this we need the usual 9% vinegar and regular soda.
Some smart guys thought that one and a half teaspoons of soda were needed for 200 ml of 9% vinegar. I tried it by eye. I took vinegar and slowly sprinkled soda on it until the boiling process stopped (I don't know what oxygen or hydrogen is released there). In general, the meaning of this process is that a reaction occurs in which an acetic acid salt is obtained - sodium acetate and water in which it is dissolved, well, the gas that is boerbulite. In general, when the reaction has passed, we pour the mixture into a saucepan and put it on gas, in order to evaporate excess water in the solution, that is, to make the solution more saturated.
This should be continued until white crystals began to settle on the walls of the pan, but I waited even longer until a film began to appear on the remaining liquid. Then I poured the remaining liquid into a jar and put it in the refrigerator to cool.
By the way, there is still a lot of pure evaporated acetate in the pan, which I would advise to collect and put in a separate jar. It can still be useful to us for the preparation of other solutions.
Now that our solution has cooled down, we can check how everything works. We take a couple of crystals from those that we scraped off the saucepan and throw them into our solution. This is where our miracle will happen - the solution will begin to solidify, as it were, and at the same time release heat, that is, everything that we observe in ordinary salt heating pads.
It remains only to return our frozen acetate back to a liquid state. We put the jar in a water bath and watch how the acetate begins to dissolve in boiling water.
And now some points.
If you recall a purchased heating pad, then crystallization there began either when the stick was broken, or when the plate was pressed. You can do the same here. As I imagine it all in the end - I take a soft container for a saline solution, pour the solution into it, throw in a small plastic stick and close it tightly. Now you can break the stick and the same process will go as in a regular heating pad.
I will say right away that in order to achieve what I got, I carried out this experiment three times until I fully enjoyed the process itself. Key features - do not overdo it with soda, do not burn the solution during evaporation. If the solution solidifies at room temperature, then it is highly saturated and should be diluted with sooooo little hot water. Well, that's all I have learned from my experiences.
As a result, we will receive heating pads of any size and in any quantity. By the way, I think it's convenient to use these when drying shoes.
That's all for today. If you have any questions, ask what I know, I'll tell you.
Good luck in heating construction!
Baking soda (sodium bicarbonate) readily reacts with acetic acid to form salt (sodium acetate) and weak carbon dioxide, which immediately dissociates into carbon dioxide and water. All components and reaction products are completely harmless, and the gas-saturated mixture actively foams, making the pies more magnificent and forcing the students to point fingers in surprise.
CH 3 COOH + NaHCO 3 → CH 3 COONa + H 2 CO 3 H 2 CO 3 → H 2 O + CO 2
Sodium acetate is widely used not only as food additive (E262), but also in the chemical industry - when dyeing fabrics, vulcanizing rubber, etc. - and, of course, as part of warming "salt warmers". This substance melts at a temperature of about 58 ° C and easily dissolves in water, and if you then evaporate excess moisture from it and cool it, you can get a supersaturated solution, waiting for only a slight "push" in order to instantly crystallize.
This exothermic process is accompanied by the release of a large amount of energy - from 264 to 289 kJ / kg. Unlike the production of sodium acetate, this is not a chemical reaction, but a physical process, a phase transition, and it is completely reversible. It is necessary to heat the mixture (for example, in a water bath), the acetate will again dissolve in the remaining water, and the "heating pad" can be reused.
Having briefly familiarized ourselves with the theory, let's move on to practical exercises. Of course, you can buy a “saline heating pad” at almost any pharmacy, and ready-made sodium acetate - at the first suitable chemical store. But why? All the ingredients you need can be found in your own kitchen.
Take a suitable container (a saucepan will work fine) and add food vinegar. Keep in mind that as a result, the volume will decrease by about an order of magnitude - we had to prepare the acetate solution in several batches.
Add baking soda carefully, do not rush, letting each new portion react, otherwise you will really have to get acquainted with the "chemical volcano". For every 500 ml of 9% vinegar solution, we used 4-5 teaspoons of baking soda.
We got an acetate solution, from which it was left to evaporate the excess water. Place the pot on low heat and let the liquid simmer until fine crystals of acetate start to appear on the sides. At the same time, the solution becomes yellowish and decreases in volume by almost 90% - this can take an hour or more.
While our solution was evaporating, we made an activator for the heating pad: we took out the base, a curved metal tape from the ruler bracelet, and cut out a circle from it, which, when pressed, bends in one direction or the other with a click. To prevent such a "button" from damaging the heating pad, it was tightened with electrical tape.
Warming "volcano"
We poured the oversaturated acetate solution into a heating pad, putting our activator in it - but in principle, the reaction can be started without it. It is enough to throw in one of the crystals that remained on the walls of the dishes, and once spontaneous crystallization began with us simply from a sharp blow. The heat in such a heating pad can last up to several hours, and for reuse it is enough to heat it in a water bath, again converting the acetate into a liquid form.
The article "Homemade heat, a chemical heating pad with your own hands" was published in the magazine "Popular Mechanics" (
When the temperature outside drops below 20 degrees, and the "grandmother's soup" standing on the balcony turns into a hefty piece of ice. A cat, a robe forgotten by someone is wrapped up. That if you shoot something on the street, then your fingers will most likely turn into icicles, which even the camera cannot be turned on. And here's the idea to make an electric hand warmer. And now the AlexGyver channel will show you how to implement this great idea.
We need a power source for the heating pad, an 18650 battery. Take it from a laptop battery or buy it in a store, buy it from the Chinese, cheap. But by the time he arrives, winter will most likely be over. But, you can take a chance. We buy nichrome wire with a diameter of 0.3 mm. All the same, the length must be manually selected. The body of the nichrome device is a 20 ml syringe, suitable for a battery.
We take a screw with M3 thread and two nuts. In the lower part of the syringe, in the center, carefully drill a 3 mm hole with a drill, having previously marked it with an awl for convenience. With a large-diameter drill, carefully remove the burrs from the inside.
From the outside, we make the surface rough with sandpaper. Using a long screwdriver, insert the screw into the resulting hole and tighten the nut almost to the very end, leaving one thread. Gently pour superglue between the screw and the syringe body, and quickly tighten the nut until the glue is frozen. This is for the tightness of the hand warmer. Sprinkle the remaining glue baking soda... The glue hardens instantly and is no longer a danger to fingers. Done! We got a fairly reliable tight connection. As you might guess, this is the first contact for the battery.
We take the plunger of the syringe and cut part of it straight into the recess. We remove burrs. For the second contact - an unbent paper clip, but thick is better copper wire... We attach or solder a flexible stranded wire to a wire or paper clip. A through hole in the piston with a thin drill and with force we insert into it the second contact of the manual heating pad. For tightness, fill in with superglue, pull it down so that it sticks better and affirm with soda. The same from the side of the elastic. We give the protruding wire a flat squiggle shape.
We will empirically determine the required length of nichrome. This is a 50 cm long folded in half. Resistance suitable for us nichrome wire, about 7-8 ohms. The longer, the less heating. The shorter, the stronger it is. 4-5 Ohm is enough to warm your hands, even in the most severe frost. You can try to run in three rows, increasing the heating area. You can safely experiment in this homemade product.
We bend it in half with nichrome and attach the upper part of the syringe to another nut. In two rows. Neat, beautiful and symmetrical. And fix the intermediate result with tape. It is unlikely to be able to wind evenly the first time, but from the second it is definitely. We make a slot and fix the remains in it, twist it. Cover the entire case with a layer of tape to protect the wiring.
We strip the wire coming from the second contact by about 1 cm.And securely we twist it with a protruding twist of nichrome. Stick this with tape, and clamp the wire into the slot. The heater is almost ready.
We insert the battery into the piston, close the contacts and wait. After a few minutes, the heating pad heats up to a pleasant temperature of 40 degrees. If there is little such heating on the street, then the length of the nichrome can be reduced, or one more turn can be added in parallel.
"Wait, wait!" you say. “But what about the button? She's not springy, does she? It is inconvenient to use such a device, it will turn on and simply will not turn off. Insert the spring? " It's hard to find the right one. But do you remember talking about tightness? We will use it. Take the original needle from the syringe and cut it off almost to its full length. Bend the remaining tip. Our goal is to round the needle so that the hand frost warmer does not allow air to pass through. You can even drop superglue into it, neatly the very drop. Now, I bent my nose tighter ...
If you like hiking in winter, you will love the review.
