Dynamo machine. Types and work. Application and features. Dynamo flashlight from a stepper motor What does a dynamo machine consist of
The channel Igor Kruch presented to your attention a new homemade product, which the author of the video made a long time ago, but all the time it was not filmed and posted on YouTube. Finally homemade big dynamo. The creation, which took about a month of work, was slowly, thought out, everything was done, qualitatively, conscientiously.
Look at the selection of hand generators and neodymium magnets at this Chinese store.
It is made from what was available: the engine, belt and tensioner from an inkjet printer. In addition: a toggle switch, a lithium-ion battery 18650. A stiffener was added. A pulley is made from disks. At idle, it produces a voltage of up to 11 volts and a current of 1.5 Amperes. There is enough power for LED lights, a low-power amplifier, a smartphone. For a laptop, this do-it-yourself dynamo machine is not enough.
So, review. The wall and bottom are made of laminate, which was left over after the repair. The pulley for the belt is made of optical discs, unnecessary, as you can see, they were drilled and twisted. The belt is large, long, yellow, from the old printer, just like the tensioner from the old printer, it was bigger. Sawed off the unnecessary part.
The generator remained the same, the handle was also bent, this is necessary so that it does not cling to the belt and tensioner. It was curved, and the position of the location of this handle has changed, so it is more convenient. In this case, the optimal gear ratio is achieved. Also, an innovation is a stiffening rib, because the walls of the laminate turned out to be too high, and it began to sway strongly, thanks to it everything is reliable, nothing staggers.
Electronics homemade generator with manual drive
It is worth saying the following. The generator, diode and capacitors remained exactly the same as in the previous dynamo. Also added one toggle switch and a battery pack. I added connectors, respectively, so that you can connect the load to it, conveniently through the connectors. On the left is a piece of sawn off laptop motherboard, a faulty motherboard. We got 3 USB ports for connecting power. A little to the right is a homemade scarf, a breadboard with 5 pins. Accordingly, 5 power consumers can be connected and 3 power consumers can be connected to 3 USB ports.
As a result, in total, in parallel together, 8 consumers can be powered from this dynamo at the same time, but so far only 2 consumers are in operation, I will also talk about them soon. The toggle switch is in front, and this is how the dynamo looks from below. Nothing special to look at: 4 rubber feet are glued to double-sided tape and 2 screws from the stiffener.
Note. The screws that twist the discs are with a countersunk head; the pulley has transverse notches (otherwise the belt slipped) and the “piece of iron” on which the pulley rotates is a core from the old speaker. Batteries are fastened to metal plates with neodymium magnets, which, thanks to the nickel coating, perfectly conduct current. The metal plates themselves are from the core of the transformer. There is grease between the pulley and the “piece of iron”, as well as between the pulley and the laminate.
A dynamo is a direct current generator that generates electrical voltage as a result of the rotation of a special drive mechanism. Such a device was widely used before the advent of alternators. Now dynamos are much less common. They are mainly used to power lighting equipment on, and also as part of the design of some types of hand-held, radio receivers, as well as portable ones for mobile phones, MP3 players and tablets.
How a dynamo works
The device consists of an inductor that, when rotated in a magnetic field, generates electrical energy. The resulting current can be transferred directly to the equipment or charged, which will feed consumers in the future. The principle of operation of the machine is explained by the physical law of Faraday. The efficiency of the device directly depends on the speed of rotation of the coil. The higher it is, the more voltage and current can be obtained.
To connect to the simplest dynamo, you can only use equipment that normally tolerates sudden surges in voltage parameters. First of all, these are LED lamps. To power more sensitive equipment, a special controller is provided in the design, which prevents the transfer of a critical charge that can harm. This is especially important if the car is designed to charge a mobile phone.
Dynamo machines for bicycles
The most efficient and functional solution for using a DC generator (bicycle generator) is to install it on a bicycle. Such a dynamo allows you to receive electricity while driving, as it is connected to the front or rear wheel. At night, without additional effort, you can illuminate the road ahead. This improves driving comfort and safety. In addition to the front light, the generator can also power the rear light.
Such dynamos may have a built-in battery that first stores electricity and only then transfers it to consumers. This eliminates the pulsation of light. If there is no battery, then the brightness depends only on the speed of rotation of the wheel. When riding downhill, when the bike slows down a lot, the light becomes very dim and practically does not allow you to see the road ahead. Modern bicycle alternators generally produce 6V. This is due to the fact that they feed the LEDs, for which this is quite enough. The old dynamos known to Soviet-era cyclists produced 12V. This was due to the fact that they powered ordinary incandescent lamps that are found on motorcycles or cars.
For bicycles, various designs of dynamos are used. Among the most popular varieties are:
- Bottle.
- Sleeve.
- Chain.
- Contactless.
bottled
Such a dynamo got its name due to its similarity in shape with an ordinary glass bottle. Its design provides for a special wheel that is applied to the side of the bicycle wheel tread. As a result of friction, it turns, which leads to the generation of electricity. This option is very common due to the ease of installation and low cost. This design has a folding mechanism, thanks to which the generator can be applied to the wheel tire if necessary or removed during the daytime, when the light is not needed.
This design is not without drawbacks. First of all, it is very noisy, and besides that, it accelerates tire wear. With long-term use, a deep groove remains on the tire, worn out by the generator wheel. It also creates resistance to the movement of the revolutions of the bicycle wheel, which reduces the overrun. In wet weather, when the tires are wet, the wheel of the dynamo will slip and the efficiency of electricity generation will decrease.
Sleeve
Such a dynamo is mounted in a wheel. This design is very successful, since it practically does not create noise. In addition, it does not stop the rotation of the wheels, which maintains the accumulated driving speed. The sleeve machine has the disadvantage of high cost as well as installation complexity. Not all bikes can mount a miniature generator without the need for complex tricks and alterations.
Chain
Chain dynamos have a special sprocket inside, which, upon contact with the chain, begins to rotate the generator coil. This design is very flimsy and if it is poorly clamped, it can deviate and get into the spokes, as a result damaging the wheel and causing an emergency. A positive aspect of such dynamos is the presence of a USB port, which allows you to recharge your mobile phone from it.
Contactless
The most perfect is the non-contact dynamo. She's pretty expensive. There are no rubbing elements in it, so the generator does not create any sound at all. Often it has a built-in battery, which allows you to accumulate energy in advance, and maintain good lighting even when moving slowly uphill. Such a device is usually fixed on the axle of the front wheel. To ensure its operation, a rim of magnets is installed on the spokes, which rotates by changing the parameters of the magnetic field acting on the coil. Usually the bezel has 28 magnets with different poles. Due to the fact that an induction coil is used in such a dynamo, energy is generated even at a low speed, only 15 km per hour.
Flashlight with dynamo
Very common are hand-held flashlights with a built-in DC generator. To get light, you need to rotate a special folding handle, which is hidden in the body for convenience. Such devices are of two types. Some have a built-in battery, while others transfer the charge directly to the LEDs. When using the former, you can pre-charge the battery and use it for a certain time without applying physical impact on the generator. Such devices give a smooth, non-pulsing light, but are a little more expensive and have more weight. The simplest are flashlights without batteries, in which the dynamo immediately transfers the charge to the diodes. Such devices glow only when the handle is rotated. If you reduce the intensity of revolutions, then the brightness decreases. In addition, there is a constant pulsation of the glow, which causes eye fatigue.
Flashlights create a lot of noise when the generator is running, so when a person who uses such a device approaches, they are more likely to learn about it by sound than by the glow of a weak LED. For the operation of the dynamo, in addition to rotating the handle, a special lever may be provided, which must be pressed and released, like a sports expander for a brush. This is a less efficient design, but allows you to receive light using one hand.
Radio receiver with dynamo
On the market you can find a radio that is equipped with a handle to generate energy. To listen to the broadcast of the radio station a little, you must first work with a dynamo and thereby charge the built-in battery. It is worth noting that this is an inefficient device that creates a lot of noise. It will not be possible to listen to music and rotate the handle at the same time, since the speaker will not be able to shout out the rattle of the generator. The only positive aspect of the radio is the creation of a load on the muscles. It acts more as a hand trainer than a full-fledged FM receiver. For this reason, many manufacturers provide for the possibility of recharging the battery built into the device from the mains. Sometimes a place may be provided in the case for installing ordinary AA batteries.
Mobile phone charger with dynamo
For outdoor enthusiasts or residents of remote areas where power supply problems are observed, a charger with a built-in DC generator will be a useful device. Externally, it is a small box with a folding handle, which, when rotated, generates an electric current of suitable parameters to power a mobile phone or other portable device. To do this, the case provides a USB port, with which you can connect the charging cable of your smartphone.
Typically, such devices have a built-in rechargeable battery, which allows you to first accumulate a charge on it, and only then transfer it to your phone, like from a power bank. Typically, a dynamo is capable of producing about 600 mAh per hour at maximum handle speed. This is a rather modest figure, so you can’t count on a full-fledged full charge with a smartphone. It will take hours of continuous operation of the handle to replenish the full capacity of the battery. Despite this, the device can help out in a difficult situation, because to make an urgent call when the phone is completely discharged, it is enough to work on the dynamo for 5-6 minutes.
Typically, manufacturers mount a solar battery on the body of such devices. Thanks to this, by placing the dynamo charger in an open area where daylight falls on it, you can gradually replenish the charge of the built-in battery without having to turn the knob. Unfortunately, a small area of the solar battery produces a flow of electricity of about 40 mAh, which is naturally very small. When deciding to purchase such a device, it must be taken into account that it is very noisy, so it will not be the best alternative to recharge a smartphone for fishermen or hunters.
If you are interested in a pedal generator to power equipment, then see the series of articles on assembling from a car dynamo and a bicycle.
The electrical circuit for powering the rear flasher is quite simple. It contains only three bright red LEDs and a 4700nF capacitor. The capacitor is used only to stabilize the voltage on one of the LEDs. The remaining two LEDs flicker during the passage of the magnets near the winding. If you want all three LEDs to flicker, you can remove the capacitor. If several LEDs are connected in parallel, the flicker-free LED will remain lit even when stopped.
In the second part of the tutorial, we will create a power circuit for five bright white headlight LEDs using two coils. This circuit is completely independent of the first rear light circuit.
- Headlight with five white LEDs
- with three red LEDs and a 4700nF capacitor
- Coil of the second circuit feeding the headlight
- Coil of the first circuit feeding the rear light
- hard drive magnet
- Relay winding
If you want to improve the schemes, then on the site you can find more advanced ones on the topic:, various types, etc.
Diagram of a rear light with a dynamo.
- old relay
- Coil contacts
- fixing screw
In order not to waste time assembling the coil with your own hands, it is better to try to find some old relay. I got the panel in the figure above from an old mini-ATS. The second picture shows a coil from a disassembled relay.
The coil resistance should be between 100 and 200 ohms. The resistance of the coil shown in the figure is 200 ohms. The greater the resistance of the coil, the more energy is generated, but at the same time the efficiency decreases due to the increase in losses in the coil.
- Stainless steel
Next, you will need to get the neodymium magnets from the hard drive. My rear wheel dynamo uses three of these magnets, but you can use many more if you can mount them securely.
- Three pulses per wheel revolution as three magnets are used
- Coil model with voltage pre-recorded from a real coil
- The main circuit of their three red bright LEDs and a 4700 nF capacitor
- Resistor used to measure currents in the simulation
- Capacitor charging, initial state 2.2 V
- LED current 3
- Coil voltage
- Capacitor current
On an oscilloscope, you can monitor the voltage generated by the coil. The recorded signal can be imported into the circuit simulator and try to simulate your project.
In the simulation, unfortunately, I did not manage to achieve constant conductivity for LED 3, despite the fact that in the real circuit I did it. Perhaps this happened due to the lack of inductors in the coil model.
Note that the circuit is not symmetrical as the energy generated by the coil is concentrated on the positive values. The distribution of energy depends on the design of the magnet and the coil used.
- The original system with batteries that are no longer needed
- Fastening
We will need a cheap LED taillight in which our new system will be installed.
Diagram of a headlight powered by a dynamo.
- "Waterproof" plastic shell
- Original flickering circuitry with five bright green LEDs
- Reflective plastic
The headlight circuit is completely independent from the first part of the project. It consists of two relay windings and a headlight.
- Dual power switch from an old computer
- Source schema
- Assembled Circuit
This is a power supply circuit for five bright LEDs using two coils. They do not generate energy at the same time. If they are connected in series, one coil will absorb some of the energy of the other coil. This does not happen in this scheme.
To flicker all the LEDs, capacitors are not specifically used here. The only place you can put a capacitor is in parallel with LED 3, since it never receives a negative voltage. As a result, you will have one non-flickering LED and four flickering ones.
The coil resistance should be in the range of 100 - 200 ohms, but my circuit uses two 600 ohm coils and everything works great for me.
- Coil 200 ohm from the first part of the instructions
- Coil 600 ohm from the second part of the instructions
A dynamo machine, or an electric current generator, is a device that converts other states of energy into electrical energy: thermal, mechanical, chemical. Bicycle alternators powering headlights and taillights remain popular to this day.
The principle of operation of the electric current generator
The dynamo generates electrical energy thanks to the principle of electromagnetic induction. Typically, such a device converts mechanical influences directly into electrical impulses. It consists of a rotor (open wire winding) and a stator, in which the poles of the magnet are located. The rotor, without stopping the movement, rotates all the time in a force magnetic field, which inevitably leads to the appearance of a current in the winding.
The dynamo machine presents the following diagram of its device. A rotating conductor, or rotor, crosses the magnetic field and generates a current in it. The ends of the rotor are brought to the ring (collector), through them and the pressure brushes, the current moves to the electrical network.
Electric current in a dynamo
The resulting current in the conductor will have the greatest value provided that the rotor is perpendicular to the magnetic lines. The more the conductor turns, the less current will be. And vice versa. That is, the process of rotation of the conductor in a magnetic field forces the generated electric current to change direction twice in one revolution of the rotor. Due to this property, this kind of current began to be called variable.
A dynamo for generating direct current is built on the same principle as for alternating current. The difference can be seen only in the details, when the ends of the metal wire are not fixed to the rings, but connected to the half rings. Such half-rings are necessarily isolated from each other, which, when the conductor rotates, makes it possible to contact with the brush one half-ring alternately, then the other. This means that the generated current will flow into the brushes exclusively in one direction, in a word, the current will be constant.
How to build a dynamo
Do-it-yourself dynamo is assembled quickly. The basis for the future generator will be a wooden board with a thickness of about 30 mm and an area of 150 by 200 mm. The housing is attached to it with two screws so that the electromagnets are located horizontally, one against the other. Then, through the bearing attached to the housing, the armature axis is threaded, which is fixed in place between the electromagnets. Brushes are threaded from the inside of the bearing rack, the second end of the armature axis is inserted. At this end, a collector is fixed.
Before attaching the bearing frame to the base, the armature must be leveled so that its rotation between the electromagnets does not interfere with them. The brushes should be located across the solenoids of the electromagnets and fixed on the bearing. A small pulley is attached to the free end of the rotor.
The electrical installation of the device consists in connecting the ends of the windings for electromagnets with brushes. Also, pieces of flexible wire are connected to them to communicate the device with an external circuit.
Generator and bike
The dynamo for a bicycle demonstrates its power depending on the speed of rotation. For example,
insufficiently fast rotation or stopping of the bicycle stops powering the lamp or other device. But at high speed, light bulbs can burn out ahead of their useful life.
There are several types of bicycle electric generators:
The sleeve type is built into the wheel hub. Structurally, it consists of a static core on the axis and a circulating multi-pole magnet in the form of a ring. Their cost is greater, it is offset by silent operation and efficiency.
The bottle type is the most popular. Similar to the shape of a bottle, the device is equipped with a small wheel, which is driven by friction on the sidewall of the rubber tire of the wheel.
The bottom bracket generator is installed next to the bottom bracket shell, below the frame stays. The movement of the spring-loaded roller is carried out due to friction against the tire tread. It should be mentioned that the bottom bracket and bottle dynamos stop working when exposed to wet conditions.
A generator that allows you to get electrical energy due to rotation (mechanical energy) is called a dynamo. The direct current generated by it, due to its qualities, is not used in everyday life as often as the alternating one. All power plants are equipped with giant alternators (alternators). Despite this, the dynamo remains a relevant device that serves well in some electrical fields, for example, when charging batteries. Therefore, a small generator, assembled with your own hands, will always find a use for itself.
Who invented the dynamo and how does it work?
In 1831, the English physicist Faraday discovered an unusual electromagnetic phenomenon. In a copper wire, during rotation between the magnetic poles, an electromagnetic field arose. It was it that excited the movement of electrons along the conductor. On the basis of research, the physicist formulated the law of electromagnetic induction. The conductor was a copper wire wound on a metal rod with a magnetic property. When the magnetic particles in the rod were arranged in accordance with the poles, it turned into a magnet and attracted metal objects to itself. A coil or a permanent magnet can be used to magnetize the rod. The effect will occur with a strong rotation of one electromagnet around another.
In the same year, a device for converting electrical energy into mechanical energy appeared. The first electric motors resembled steam engines: only electromagnets were installed instead of cylinders, metal anchors instead of pistons.
In 1834, Russian academician Boris Jacobi created the first electric motor with a rotating armature. After 4 years, the academician used an improved electric motor on the world's first motor boat. The world's first alternating current generator was built by Pavel Yablochkov. And truly revolutionary was the invention of another Russian scientist M. Dolivo-Dovolsky - a three-phase current generator.
DIY dynamo, its elements
In order to build a dynamo, you will need such basic elements as a body, a rotating armature, a collector, a brush holder, brushes, copper wire with insulation.
Consider the preparation of each element separately.
Dynamo device |
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| There are different options for making the case. A tin can, a piece of pipe (diameter 100 mm) is suitable for it. First, you need to cut the bottom of the can and make the case heavier. To do this, on the inside or outside of the can, we wrap a strip of iron of the same width very tightly in several rows. Then we rivet or solder the strip to the body. Secondly, we make cores for electromagnets and shoes for them from tin or iron. We take strips of tin along the width of the hull, bend them, put them on top of each other, fasten them with iron wire and solder them along the sides. We attach the cores to the holes in the housing located opposite each other. Using screws, we screw the body to the block (wooden or metal). In the case we make two bearing strips (brass or thick tin, size 110x20 mm) and a stand (80x20 mm) for fixing the anchor. We solder the strips with a cross, in the center we make a hole along the diameter of the axis. The same hole in the rack 10 mm from the end. Copper tubes (10-15 mm with a diameter of 8 mm) can be soldered into the bearing holes. We solder the first bearing to the body with the ends of the strips, after which the system will bend outward. |
| It is necessary to make the anchor carefully, since it largely depends on how the dynamo will work. You can assemble an anchor from tin plates. The thickness of all plates must be equal to the thickness of the body (50 mm), and special precision is required in their manufacture. About 120 circles (46 mm in diameter) will have to be cut out of iron. We divide each circle into eight sectors using a compass, make markings through the center of the circle, in the center of the circles we draw two circles with a diameter of 8 and 38 mm. At the intersection of the large circle with the lines of the sectors, we draw more circles of 8 mm each. On all round plates, where the circles were drawn, we drill eight holes of 8 mm each with accuracy. We tightly fasten the plates with nuts and put them on the axle, we should get an anchor with round longitudinal grooves. Sharp corners in the grooves are rounded off with a file. |
Manufacture of the collector and brush holder
When assembling a dynamo, in particular the collector and brush holders, attention and accuracy are required.
| The collector can be made from a tube (copper, brass) or assembled from plates. You will need a tube with a diameter of 20-25 mm and a length of 25-30 mm, which is sawn into 4 equal parts. Two two-millimeter holes are drilled in the plates. Then we cut out a cylinder (diameter 20-25 mm, length 25 mm) from fiber or ebonite, dry wood is also suitable. We make a hole in the center of the cylinder so that it can fit tightly on the anchor axis. We fix the plates to the cylinder with the help of small screws, each time leaving a space of 1-2 mm between them. You can use twisted wire and insulating tape. The screws must not touch the axis, otherwise there will be a short circuit. The gaps between the plates are filled with rosin. |
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| A brush holder with brushes is used to relieve stress in the collector. The brushes must extend and rotate around the armature axis in order to change the force and angle of pressure on the collector. We will make a 10 mm thick base from fiber, ebonite or paraffin wood. We drill three holes in it so that the bolts fit for the two extreme ones. We take copper bolts or 35 mm radio contacts. The bolts securing the brushes are screwed in with nuts for clamping. The hole in the center should be the same diameter as the copper tube used for the first bearing in the housing. Opposite the central hole in the end of the block, we drill a through hole and make a thread for the fixing screw. We take a screw (for wood - a screw) with a slot or edges on the head. We make a hole slightly smaller than the diameter of the screw, screw the screw. First, screw in 2-3 turns, then turn it out, repeating until it enters freely for three turns. Then, in the same way, we process the next pass with a screw. We make a bearing rack, at the upper end of which we drill a hole, insert a piece of copper tube and solder it. Brushes can be made in many ways, from copper, brass plates or carbon brushes. These can be plates 40-50 mm long with a cross section of 10-15 mm. At the end of the brush, we drill an oblong through hole 20 mm long for the bolts. Such a hole will allow you to change the pressure, bringing the brushes closer to the collector. Fasten the brushes with washers. To make the brushes tightly touch the collector, we sharpen their ends obliquely. |
Winding
For winding we will use copper wire with paper insulation with a cross section of 0.5-0.8 mm. It is necessary to purchase half a kilogram of wire, the thickness of which will affect the voltage and current strength. For example, when winding with a 0.5 mm wire, 25 volts will be generated at a current of 1 ampere, if you take a wire of 0.8 - 8 volts at a force of 3 amperes. Before starting work, we divide the wire into two parts. To wind the electromagnet, you will need 450 g of wire 0.5 and 60 g for the winding of the armature. If you bought a wire of 0.8, set aside 430 g for the electromagnet, and 70 g for the anchor.
Dynamo assembly
Do-it-yourself dynamo is assembled in several stages:
- For the base, we will prepare a board measuring 150x200 mm, 30 mm thick. Let's drill two holes from the edges of the ring of electromagnets.
- We fix the body to the base with two screws so that the electro-magnets are located on the same horizontal line opposite each other.
- To the sides of the case, so that it sits firmly, we put wooden blocks and screw them to the base.
- Then we pass the free end of the armature axis through the bearing on the housing. We insert it into place between the electromagnets.
- We put a brush holder with brushes on the bearing of the bearing rack from the inside and insert the end of the armature axis with the collector. A thick metal washer or wire ring must first be put on the collector.
- We set the anchor so that when it rotates between the electromagnets, it does not touch them and is at the same distance from them. The stand is attached to the base with two screws.
Dynamo adjustment
- We fix the brushes so that they lightly touch the collector and do not strongly slow down its rotation.
- We will check the correctness of the connections, the absence of breaks and short circuits. We connect a battery of 15-20 volts to the mechanism. If the motor is running, the armature is rotating quickly, which means that the dynamo is assembled correctly with your own hands.
- After checking, we connect the dynamo to the drive, for example, from a foot sewing machine. We connect a voltage from a 10 volt battery to the brushes to magnetize the electromagnets. After a minute, the battery should turn off, then we begin to quickly rotate the armature using the drive. We connect a voltmeter or a 12 volt lamp to the wires from the brushes. If everything is assembled correctly, the voltmeter will show voltage, and the light bulb will glow.
- With the help of uniform rotation of the armature, it is necessary to slightly turn the brush holder in the direction of rotation of the armature, then the brushes will spark less and better relieve stress. We will experimentally adjust the installation of brushes.
Bicycle dynamo
A small generator for a bicycle is mounted on the side wall of the tire. It allows you to charge the batteries of mobile phones, receivers and other devices, lights the headlights. The bottle dynamo is also called the side dynamo. When driving, the tire drives the dynamo roller, which rotates the electric generator.
For a bicycle generator, you can take a dynamo hub, a dynamo carriage. A non-contact dynamo will also work. She will be able to charge the phone quite successfully.
- A bottle generator creates resistance while running and requires more effort to spin than a hub dynamo. Proper adjustment will help reduce drag.
- A bicycle bottle dynamo wears out the tire, unlike a hub dynamo.
- When wet, the roller of the dynamo bottle will probably slip over the tire, which will significantly reduce the amount of energy generated.
- A hub dynamo does not require good adhesion and sealing. They do not make noise, unlike dynamos.
Cycle dynamo operation
Careful setting of the dynamo is very important, taking into account the angle, height and pressure. To start, the bottle-type bicycle dynamo is moved and connected, and the hub dynamo is simply turned on manually or automatically.
The dynamo must be operated strictly according to the instructions.
- Before pedaling, check the voltmeter. It should show voltage (12-13).
- We select the low power mode, turn on the generator, the indicator light should light up.
- We pedal, gradually increasing the speed, until the generator turns on. The light went out, the value on the voltmeter is 13-14. Pedaling must be fast so that the circuit can maintain power.
- A bicycle dynamo works more efficiently at high power. For heavy loads, it is better to start the generator at low power, and after disconnecting the load, switch to high power.
Dynamo charger
In the field, a simple “twist”, a dynamo for charging the phone, will always come in handy. Chargers with a built-in battery are relevant. There are mechanical chargers that also do not take up much space. Many modern "twists" are equipped with flashlights.
These devices quite successfully charge mobile phones. For example, when turning the knob 2-3 revolutions per second, you can get a coefficient value from 0.65 to 2.5. I twisted it for a couple of minutes and you can talk on the phone from 2 to 5 minutes. It all depends on the model and conditions of reception. A hand-held dynamo will not be able to power a powerful smartphone with a large display. Mechanical charging will provide results in conjunction with a simple phone along with a hands-free headset.
Charging the dynamo machine will work effectively when the battery is completely discharged, but you can only increase the charge of the phone by twisting the handle up to 50%. When the battery is only half discharged, the spinner becomes a useless toy. If the instructions indicate the maximum charging current - 400 mA with a power of 2 W, then additional energy cannot be squeezed out even with a quick rotation of the handle.
Powerful do-it-yourself generator
A powerful electricity generator can be assembled using an old bicycle without eights on the rear wheel. A 28-inch wheel and a 52-tooth front sprocket will do, but other options are possible, such as a 26-inch and a 46-tooth sprocket. First of all, we remove unnecessary parts: the front wheel, tires, gear shift, brakes. We put the bike on the stand.
The generator must be self-contained with two large terminals and one small one. We connect two large terminals together, forming a plus, and a small one - with an indicator light. Connect the ground terminal to the housing (minus). We clean the generator, remove the cooling fan from it. We fix the generator on the bracket behind the seat, the spindle should be outside 10-12 cm from the rim. We select a belt, preferably a toothed one, with a circumference of approximately 82 inches. For 26-inch wheels, A78 belts will fit, and for 27-inch wheels, A80 belts.
To adjust the tension of the alternator, we use a spring-type tensioner. The belt does not need to be tightened too much, as the torque is quite low. We fix a voltmeter, a switch and a light bulb on the steering wheel. If there are children in the house, it is necessary to protect the moving parts of the mechanism in order to exclude the possibility of injury.