Homemade hand warmer with your own hands. Pocket Reactor - Homemade Catalytic Hand Warmer Step by step manufacturing plan
Hello to everyone. Fishermen, hunters, tourists, in general, to everyone who reads this article.
Today I will share my idea - how to make a hand warmer from a SIMPLE PENCIL.
Such a heating pad can give very good heating, with a relatively small consumption. (SPECIFICALLY what I got will be lower).
THIS ARTICLE IS NOT AN INSTRUCTION FOR ASSEMBLY OF HAND HEATERS, BUT ONLY A DEMONSTRATION OF MY IDEA, ITS IMPLEMENTATION AND WHAT IS GOING FROM IT. REMEMBER YOUR SAFETY IS IN YOUR HANDS.
As a basis for such a heating pad, I took the most ordinary graphite pencil (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, the wood is denser there, the heat transfer is better + -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 - I vibrated the length and the desired heating.
turned it to the desired diameter (cleaned off the paint, reduces heat dissipation) - made additional cuts.
Here such a thing came to light the neck itself (without a shell) - it heats very strongly - usually + 15C to the fact that it is 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. There is a lot of trouble, there is little sense. I decided to leave it in its native shell - I just grinded it off as much as possible and made cuts. ON THE 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 compress properly).
I tried two such options for connecting a wire to graphite.
I liked BOTH options (in my own way). If you know your a good option connections to graphite-write-it will be interesting.
After connecting the wire, everything was carefully packed with heat shrink.
It turned out here is such a heating pad from POVERBANK.
At the time of the creation of this article, she worked for more than 150 hours (an average of 3-6, depending on the power bank). The heating pad works clearly - the power banks are also 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 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 at a good ratio of + 45 + 50C OR + 30 + 35 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 strain)
The shell is also a matter of aesthetics and convenience - the main thing is that it would have good thermal conductivity.
Well, in principle, all dear readers, the heating pad works and warms.
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 our hands warm. So I decided to whip up a mini heating pad specifically for my precious hands. There are a lot of heating pads of this kind on the markets, but still I wanted to make my own.
On sale there are heating pads with a combustible mixture inside, these are long-term reserve hiking heaters based on the principle of catalytic combustion. There are also electric heaters with a built-in battery and a 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 underfloor heating, they are also wrapped around water pipes so that the water in the latter does not freeze. Well, in general, there are a lot of applications for such a heater.
The heater consists of two parts - a fibrous resistive material that actually heats up, and a heat-resistant flexible insulation.
Such heaters are powered by the mains, 10 meters of such a wire consumes about 160 watts when powered by a 220 volt mains. It was this material that I decided to use in my heating pad.
Selected by experience optimal power heating element, a nichrome heater was used for this. I wound the wire on the aluminum frame of the power bank and chose the length so that when powered by 12 and volts, the case would heat 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 desired length of the heater, but you need to take into account the fact that as it heats up, the resistance of the heater will increase, therefore the power will decrease, the length and resistance for my case are not so important, since everyone will calculate the heater individually depending on the supply voltage and heater length.
The heater will be powered by just one standard lithium can 18650 , but not directly, but through a boost converter, it is possible without it, but in order to get the desired power from 3.7 Volts, you need to shorten the length of the wire and connect several in parallel. In order to avoid a collective farm, I decided to use a converter, in which case the heater will be solid and will stretch along the entire length of the sleeve, thereby ensuring uniform heating.
In a heating pad, the battery must be protected, otherwise it may fail due to deep discharge.
Between the turns of the heater, he kept some distance, having received something like notches for the 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 input of the board and set 12 Volts at the output of the module by rotating the trimmer resistor. My case turned out to be too small and the converter board simply didn’t fit, but I didn’t want to change the case, in the end I decided to modify the inverter board with wire cutters, and that’s what happened.
The dimensions have decreased by two and a half times.
Let's take measurements of power and operating time. We supply a voltage of 3.7 volts to the input of the inverter, simulating a battery, we 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 2200mAh battery, it will last a little more than an hour continuous operation of the heating pad, and if this is not enough, you can take a 3400 mAh battery.
A heat-resistant adhesive tape is wound on the aluminum case of the power bank, in principle it is not needed, it was originally used to insulate 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 truncated converter board, I had to lengthen the case, since I completely forgot that at the beginning I planned to shove a USB charging system here.
The heater is turned on with a non-latching button.
The button is located right under the thumb, which is convenient, no matter which hand you have the heating pad in. The button is not involved here with ease, since the heating pad will mainly be in your pocket, there is no guarantee that you will not leave it on, but there will be no such problems with the button, let it go and everything turned off.
The charging circuit is based on TP4056, nothing new. This fee also had to be reduced.
Well, now turn on the heating pad and measure the temperature.
I think the result is excellent, if you hold the heating pad in your hand, part of the heat will be removed by your very hand. and if it is too hot, then the temperature can be reduced by reducing the output voltage of the inverter, it was not in vain that I made a hole for adjustment.
Hello my little craft lovers!
Today I will tell you how to make at home SALT HEATER.
Yes, yes, I'm not mistaken. Exactly salt heater, which is sold in pharmacies and which was 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 necessary for its manufacture is at our place. You don’t need to buy anything special, well, if only the container itself. I myself am thinking of using packages for saline solution used in droppers as a container.
So let's get started.
I warn you right away, I am not a chemist, even very far away, so if real chemists notice any inaccuracies in my descriptions, please correct me. The whole point of what we're going to do is get sodium acetate. And for this we need the usual 9% vinegar and ordinary soda.
Some smart guys thought that for 200 ml of 9% vinegar you need one and a half teaspoons of soda. I tried by eye. I took vinegar and slowly sprinkled soda on it until the bubbling process stopped (I don’t know if oxygen or hydrogen is released there). In general, the meaning of this process is that a reaction occurs in which a salt of acetic acid is obtained - sodium acetate and water in which it is dissolved, well, the gas that burbulite. In general, when the reaction has passed, pour the mixture into a saucepan and put it on gas in order to evaporate the excess water in the solution, that is, to make the solution more saturated.
This must be continued until white crystals begin 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 you 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 from 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 heaters.
It remains only to return our frozen acetate to a liquid state again. We put the jar in a water bath and watch how the acetate begins to dissolve in boiling water.
And now some points.
If we recall a purchased heating pad, then crystallization there began either when the stick was broken, or when the plate was pressed. Here you can do the same. As I imagine it all in the end - I take a soft container for a saline solution, pour the solution into it, throw a small plastic stick and close it tightly. Now you can break the stick and the same process will go as in a conventional heating pad.
I will say right away, in order to achieve what I got, I carried out this experiment three times until I completely smoked the process itself. Key Features- do not overdo it with soda, do not burn the solution when evaporating. If the solution solidifies at room temperature, then it is highly saturated and should be diluted with a very small amount hot water. Well, that's all I've learned from my experience.
As a result, we will get heating pads of any size and in any quantity. By the way, I think it is 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 with your heating projects!
Baking soda (sodium bicarbonate) reacts very readily with acetic acid, forming a salt (sodium acetate) and weak carbonic acid, which immediately dissociates into carbon dioxide and water. All components and reaction products are completely harmless, and the mixture saturated with gas actively foams, making pies more magnificent and forcing schoolchildren 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 finds the widest application 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 heaters". This substance melts at a temperature of about 58 ° C and dissolves easily in water, and if then the excess moisture is evaporated from it and cooled, a supersaturated solution can be obtained, waiting only for 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 worth heating the mixture (for example, in a water bath), the acetate will dissolve again in the remaining water, and the “heater” can be reused.
After briefly reviewing the theory, let's move on to practical exercises. Of course, a “salt heating pad” can be bought at almost any pharmacy, and ready-made sodium acetate can be bought at the first suitable chemical reagent store. But why? All the ingredients you need can be found in your own kitchen.
Take a suitable container (a saucepan is fine) and pour in the vinegar. Keep in mind that as a result, the volume will decrease somewhere by an order of magnitude - we had to prepare the acetate solution in several batches.
Carefully add the baking soda, don't rush, letting each new batch react, otherwise you really have to get acquainted with the "chemical volcano". For every 500 ml of a 9% vinegar solution, we used 4-5 teaspoons of baking soda.
We got an acetate solution, from which it remains to evaporate the excess water. Put the pan on low heat and make sure that the liquid boils slowly until small crystals of acetate begin to appear on the walls. The solution then turns 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 ribbon, from the ruler bracelet, and cut out a circle from it, which, when pressed, bends either in one direction or the other with a click. So that such a “button” does not damage the heating pad, it was tightened with electrical tape.
Warming "volcano"
We poured the supersaturated 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 inside 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 transferring the acetate to a liquid form.
The article "Home-made heat, do-it-yourself chemical heating pad" was published in the journal "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. Kitten, wrapping up a dressing gown forgotten by someone. That if you shoot something on the street, then your fingers will most likely turn into icicles, with which you won’t even be able to turn on the camera. And then the idea to make an electric hand warmer. And now the AlexGyver channel will show you how to implement this wonderful 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, it's cheap. But by the time he arrives, winter will most likely be over. But, you can take a risk. We buy nichrome wire with a diameter of 0.3 mm. Still choose the length manually. The case of the nichrome device is a syringe with a volume of 20 ml, suitable for a battery.
We take a screw with an M3 thread and two nuts. At the bottom 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.
On 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 has hardened. This is for the tightness of the hand warmer. Sprinkle the rest of the glue baking soda. The glue instantly hardens and will no longer pose a danger to the fingers. Ready! Received a fairly reliable hermetic connection. As you might guess, this is the first contact for the battery.
We take the plunger of the syringe and cut off part of it directly into the recess. We remove burrs. For the second contact - an unfolded paper clip, but a thick one is better copper wire. To a wire or a paper clip, we wind or solder a flexible stranded wire. With a thin drill a through hole in the piston and with force we insert the second contact of the hand heater into it. For tightness, fill with superglue, pull it down so that it sticks better and approve with soda. Same for the rubber band. We give the protruding wire the shape of a flat squiggle.
Empirically, we determine the desired length of nichrome. This is a 50 cm long segment folded in half. Resistance suitable for us nichrome wire, about 7-8 ohms. The longer, the less heat. The shorter, the stronger it is. 4-5 ohms is enough to warm your hands, even in the most severe frost. You can try to start up in three rows, increasing the heating area. In this homemade product, you can safely experiment.
We bend the nichrome in half and fasten the top of the syringe to another nut. In two rows. Neat, beautiful and symmetrical. And we fix the intermediate result with adhesive tape. It is unlikely that it will be possible to wind evenly from the first time, but from the second it is already accurate. We make a slot and fix the remains in it, twist. Cover the entire body with a layer of adhesive tape to protect the wiring.
We clean the wire coming from the second contact by about 1 cm. And we twist it securely with a protruding nichrome twist. Stick it 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 warms up to a pleasant temperature of 40 degrees. If there is little such heating on the street, then the length of nichrome can be reduced, or another turn can be added in parallel.
"Wait, wait!" you say. "But what about the button? She doesn't bounce, does she? Using such a device is inconvenient, it will turn on and just not turn off. Insert spring? It's hard to find the right one. But, remember, I talked about tightness? Let's use her. Let's take a native needle from a syringe and cut it off almost to its entire length. Fold over the remaining end. Our goal is to round the needle so that the hand warmer does not let air through. You can even drop superglue into it, neatly just a drop. Now, bent the nose tighter ...
If you like hiking in winter, you will love the review.
