For a child, and with good assembly, you can develop the idea into, for example, an office souvenir.
The basis of the toy is a simple overhead circuit (although it is of course better to do it on a board), consisting of a transistor, a diode and a specially wound coil hidden in the bottom. The “seat” of the swing is a magnet, it is better to choose a neodymium one, there are plenty of them now, although a regular one will do just fine.
The reel is winding double wire each with a cross-section of approximately 0.25-0.3, about 1500 turns, i.e. 2 copper wires are taken in parallel and wound onto a coil. The diagram shows that the end of the first wire is connected to the beginning of the second. I chose the shape of the coil for logical reasons: oval, because a magnet passing over it will interact better along the length of the larger diagonal of the ellipse. I didn't use the core, so you can experiment with it. It is better to wind it carefully, turn to turn, but it is not necessary.
A direct conduction transistor, you can take MP39...42, any diode, a regular 1.5 volt battery. For convenience, it is better to make a switch.
I apologize for the makeshift assembly, but I did it in my school years out of sheer enthusiasm using a diagram from my father’s old notebook with diagrams, so it’s not really known where it came from, and I just wanted to see how it works as quickly as possible.
It starts up simply, turn on the device and push the magnet, after a couple of seconds you will notice how intensely the pendulum begins to oscillate. The system will work better if it can create resonance, i.e. equality of the operating frequencies of the circuit and the natural frequency of the pendulum, which is calculated by the formula. Here this is achieved by adjusting all the parameters of the pendulum. It is better to secure the connecting rod on 2 bearings, and not on 1, like mine.
Newton's Cradle.
Hello. The other day I decided to make something interesting and educational for my son; my attention focused on Newton’s pendulum or, as some also call it, Newton’s cradle (and sometimes even Newton’s balls).
He is mechanical system, which was invented by an English actor in 1967, his name was Simon Prebble.
You, of course, saw this pendulum in the physics classroom; the teacher, using its example, explains to children how energy of different types is converted into each other, for example, potential energy into kinetic energy and vice versa.
Tools I used:
1) Pliers.
2) Hammer.
3) Beard.
4) File.
5) Soldering iron.
6) Wire cutters.
7) Tweezers.
The only materials I needed to make the pendulum were:
1) Bearing.
2) Rosin.
3) Solder.
4) Copper wire (thin).
5) Thick copper wire (four square millimeters).
6) Threads.
7) Glue.
To begin with, I would like to talk a little about how I removed the balls from the bearing. It’s just that one friend told me how he and his friend pulled them out not entirely safely, one might even say not at all safe method and almost lost their eyes. He said that he placed the bearing on a hard surface, hit the cage with a hammer and the balls scattered (two balls were lost). I didn't take that risk and started disassembling it.
First I removed the seals.
Then, resting the bead on the separator (where the rivets are), with a slight movement of a hammer, I riveted and bent the separator to the other side in several places and dismantled it with pliers.
Next, having grouped all the balls, I used pliers to move the inner ring towards the outer ring.
With such simple manipulations I was able to easily pull out the balls without harming myself or others. Moreover, not a single ball left my field of vision.
Next, I used a file to clean the area where I would solder the ring.
I gave this place a good rinse with rosin.
I found a piece of small cross-section stranded wire in the bins. I pulled out one vein with pliers.
And he made rings out of it.
I soldered the rings onto the ball. I tried to keep it as straight as possible.
As they say, the first ball is lumpy. I overexposed the soldering iron tip to the ball, and it darkened (received a thermal burn: wink:).
To ensure that the rings were at least a little similar to each other, I checked them against the already prepared ones. Then he did the same manipulations with the remaining balls.
As a result, I ended up with seven not very beautiful (rosin-stained) Cheburashkas, and one of them became Negroid.
After processing with felt with goy paste. (Even the African American began to shine). As I realized during the tests, I should not have placed the balls on the magnet; they became magnetized and had to be demagnetized. I did this using a frameless magnetic coil taken from a non-working old TV. Information for those who want to demagnetize these coils is only available on old-style TVs with a cathode ray tube; otherwise, almost any frameless coil is suitable. And one more detail, the voltage supplied to the coil must be variable.
Then there is a long and painful process of threading the thread through the rings.
Having cleared the insulation from a wire with a cross-section of four square millimeters, I began to make the frame of the future pendulum.
At first I made a frame like in the bottom photo, but it was ineffective, it turned out to be too low (there was not enough acceleration) and it took part of the energy of the balls (the antennae holding the balls swayed).
And it was decided to make a stronger and slightly higher structure.
I tied the threads, making several turns. This is done so that when adjusting the location of the balls by turning the thread, it does not spin back under the weight of the balls tied to it. From the beginning I simply tied the threads to one side of the resulting frame.
Then (while adjusting) he tied it to another beam.
And in the end, I adjusted the balls (by twisting the thread onto the beam) so that they lined up in one row as accurately as possible, because this also greatly depends on how long it will click. After fine-tuning, I applied over the threads tied to the beam a small amount of glue, thereby securing them from scrolling and moving along the beam.
The operation of a huge number of devices and machines is based on the properties of the electromagnet. Most pendulums in modern electric clocks are also driven by an electromagnet. Let's try to understand the reasons that make the electric pendulum swing tirelessly, and we'll make a small model of it ourselves.
For this we will need: a homemade electromagnet, the same as we made when making an electric bell, tin, one or two batteries or a step-down transformer.
The pendulum is cut out of tin according to the pattern shown in Figure 1. The internal hole is knocked out with a chisel along the lines of the drawing, hitting its handle with a hammer. To do this, the tin with the drawing printed on it is placed on a flat hardwood board. Then, having cleaned the sharp burrs of the hole with a file, cut out the entire pendulum figure with ordinary scissors along the outer contour. After this, sand all the edges again with a fine file, and roll the bottom strip - the tongue - into a small tube. When folded, it will serve as the usual weighted end of a pendulum. In the upper part of the figurine, drill or punch a small hole with a steel awl, the edges of which must be carefully sanded with fine sandpaper. This small hole is used to put the pendulum on. a thick steel needle or a piece of knitting needle hammered into the upper part of the vertical post C (Fig. 2).
The pendulum must be hung on a needle so that its lower part, rolled into a tube, is located just above the ends of the protruding poles of the magnet, almost touching them, but
when swinging, it would not touch the protruding ends of the core.
To avoid friction of the pendulum on a wooden stand, place a small piece of copper tube with well-polished edges on the axis. Two copper nails must be installed on the sides of the upper protrusion of the pendulum. They will keep the pendulum from swinging too far.
Electric current is supplied from a battery or transformer (4 - 6 volts), according to the diagram shown in Figure 2. All wire connections must be well cleaned and soldered.
In Figure 2 you see a thin, elastic wire-breaker P. The breaker ensures continuous swinging of the pendulum. The first swing of the pendulum should be made with a slight movement of the finger, bringing it side part to the breaker. In this case, the electrical circuit will be closed through one of the upper pins, the current will run through the winding of the electromagnet, and its core will instantly attract the lower weighted end of the armature. As soon as the lower part of the pendulum is pulled down, the chain opens and the pendulum moves to the opposite side. Here the other side of the pendulum will again encounter a breaker, which will cause the magnet to pull the pendulum down.
The pendulum will swing in this way until you disconnect the entire model from the current source - a transformer or battery.
A very interesting model of an electric pendulum can be made in the form of a swing, and on the seat you can attach a Pinocchio figurine cut out of paper or cork. The little man - the children's favorite hero - will fly up and fall down in the most mysterious way.
Other original views hours. The clocks proposed in this manual, although also electronic, use the oscillatory motion of a pendulum to keep time. This is the so-called free pendulum clock.
The accuracy of such a clock depends on the design of its pendulum, on minimizing the influence of temperature, on the method of supplying energy that supports the oscillatory motion of the pendulum and receiving energy from the pendulum. In a classic mechanical watch, this is done by a gripping mechanism and a set of gears.
For the accuracy of the clock to be as good as possible, the pendulum must oscillate absolutely freely, unencumbered by mechanisms. And energy is transferred in very small portions at the moment when the pendulum is in the lower position and only in the case when the amplitude of the pendulum’s oscillations decreases below permissible value. Transferring energy in too large doses causes an increase in the amplitude of vibrations, which leads to a decrease in accuracy. The amplitude of the pendulum's oscillations should not exceed several degrees.
Schematic diagram of the clock
The basis of a pendulum clock is a structure with a bearing with a neodymium magnet attached to the end. An induction coil is located at the base. As a result of the movement of the pendulum directly above the coil, a voltage is induced in the coil, which is transmitted to the PIC12F683 microprocessor, which analyzes the induced voltage and at the right moment supplies the coil with a voltage pulse that maintains the movement of the pendulum.
- When the magnet at the end of the pendulum approaches the coil, the induced voltage in the coil is negative,
- when it passes over the middle of the coil, the voltage has a zero value,
- when it moves away - a positive value.
The amplitude of the pulses induced in the coil depends on the speed of movement of the magnet above the coil, and, consequently, on the amplitude of the pendulum’s oscillations. By measuring the voltage after a strictly defined time of passing the equilibrium point through the pendulum, it is possible to estimate what the amplitude of the oscillations is, and therefore whether an impulse should be provided to the oscillation stimulator or not. The higher the quality factor of the system, the less often it will be necessary to create this impulse.
To display the time, a quartz clock mechanism is used, powered by a 1.5 V battery. In it, we remove the plate with the quartz resonator and the circuit, using only the mechanism itself. We connect the motor-coil leads to the microcontroller ports. The MK generates a pulse every second in turn at one or the second output of the coil.
In total, several different clocks were made with different pendulum lengths. The largest was a pendulum with a length of 1000 mm, where the half-period of oscillation was exactly 1 second. There were also oscillation half-periods of 1/3 second (110 mm) and 1/4 second (60 mm). Thus, the impulse for the stepper motor was generated, respectively, for the first, third or fourth passage of the pendulum over the equilibrium point.
The clock is powered lithium-ion battery type 18650, they will last for several months of work. The processor uses an LM385-1.2 stabilizer, which produces a voltage of 1.2 volts. When the processor detects that the battery voltage has dropped below 3.28 V, it alarms every two seconds. The timer can also work with a battery that is down to 2 V, but such a deep discharge should be avoided due to the possibility of battery damage.
The induction coil must have several thousand turns. In this watch, 2000-3000 turns of 0.12 wire were wound. The coils have no core and are wound on a frame with a diameter of 6 mm. The pendulum rod must be made of a material with the lowest possible coefficient of thermal expansion; a carbon fiber rod is a good choice. The length of the pendulum should be selected so as to obtain the required period of oscillation. It is necessary to take into account the possibility of fine-tuning the oscillation period, which is served by an additional weight placed on the pendulum - a brass nut, the rotation of which changes the distribution of mass on the pendulum.
Attention: ferromagnetic materials such as steel nails and screws should not be located near the magnet at the end of the pendulum. Also be careful with brass and copper elements. A magnet moving in their immediate vicinity excites eddy currents in them, which slow down the movement of the magnet. Therefore, the base of the watch should be made of wood, plastic, laminate, marble, etc.
The electronic circuit contains only a processor in a stand, a zener diode through a 100 kohm resistor and connectors for a battery, coil and stepper motor. The circuit was assembled on a small printed circuit board, cut from a universal plate. Hex files containing processor firmware - .
Some houses have them - a large antique clock in a polished mahogany cabinet, with a pendulum and two large shiny weights on chains. There is something mysterious hidden in such watches - through them, it’s as if time itself speaks to us about the past, the present, and the future...
I dreamed of a clock with a pendulum for a very long time, but somehow I didn’t get one as an inheritance from my second cousins, and in thrift stores they asked for the kind of money for which one could buy a quite decent car like a VAZ.
But one day in a store I came across an ordinary digital wall clock - and with exactly the dial that I had seen in my dreams. Without thinking twice, I bought them - they were not expensive at all. I bought it because they instantly appeared in my thoughts - the watch that I had dreamed of for so long and which differed from electronic ones only in a cabinet with a glazed door and a regularly swinging pendulum. But I’ll try to make the cabinet and pendulum myself!
The watch case came from an old bookshelf - I sawed it lengthwise into two unequal parts, and the smaller one, 120 mm wide, became the base of the cabinet. Well, from the boards left after this operation, I cut out blanks for the door and glued them together epoxy resin and glazed it. By the way, the W-shaped one is quite suitable for fastening the glass. plastic profile- this is usually used for installing “engines” in cabinets and bookshelves, however, it did a good job of replacing glazing beads when glazing the door.
The greatest difficulty was caused by the reproduction of the pendulum mechanism. Of course, it would be possible to design a real pendulum that would set the accuracy of an electronic clock, but there was no reason to create such a complex device, and I developed a much simpler electromechanical device that completely imitates the movements of a pendulum.
The pendulum is a rod made of a polished duralumin tube with a diameter of 12×1 mm, having a suspension point on a line dividing it in a ratio of 1:2. The suspension hinge is a steel bracket with two M5 set screws with conical ends screwed into it. Two cylindrical holes with a diameter of 2 mm are drilled in the pendulum rod, respectively. At the bottom of the pendulum, a decorative disk and a weight are attached - the first is made of a compact disc, and the second of a steel strip. If necessary, by decreasing or increasing the load, you can change the frequency of oscillations of the pendulum.
1—electronic watch; 2— cabinet body; 3—electromagnet; 4—pendulum anchor; 5—cabinet door; 6—jumper for attaching switches; 7—loop; 8—contact petal of the switch; 9—conductor; 10—pendulum hinge; 11—shelf for mounting an electronic clock and a pendulum; 12—pendulum rod; 13 — imitation of a clock weight; 14—imitation of a pendulum disk; 15—rear wall of the housing; 16—pendulum weight
1—contact petal (foil-coated textolite s2); 2 - connecting wire; 3 — switch housing (D16 sheet 1.5); 4—washer (polyethylene); 5 — centering screw return spring; 6—return spring; 7—return spring centering rod
A—the pendulum begins to move, while the contactor touches the contact blade of the first commutator, thereby turning on the power supply circuit of the electromagnet; B—when the armature approaches the axis of the electromagnet, the contact petal slides off the contactor—and the power supply circuit of the electromagnet is broken; B - after stopping at a dead point, the pendulum begins to move in the opposite direction, the contactor touches the contact blade of the second commutator and turns on the electromagnet power circuit.
The numbers on the diagram indicate:
1—electromagnet; 2—pendulum anchor; 3—conductor; 4—pendulum rod; 5—axis of pendulum swing; 6—switches
An anchor is fixed at the top of the pendulum rod - it will require a strip of soft (annealed) steel 4 mm thick. To attach it to the rod, a M12x0.5 mm thread is cut into the hole drilled in the anchor.
The “motor” of the pendulum is an electromagnet - it can be made from an output transformer or an inductor from an old one tube receiver or broadcast loudspeaker. You just need to sort through its core, consisting of the main W-shaped and closing rectangular plates, the latter should be removed (they will not be needed for the electromagnet), and a new core should be folded from the first in the form of a thick letter “W”. The winding will have to be rewound in accordance with the amount of current that the source can provide - for example, Charger For mobile phone. Practice has shown that when using a source direct current with a voltage of 5 V, a winding made of PE type wire with a diameter of 0.3 mm is quite suitable when wound in bulk until the frame is filled. By the way, it is most convenient to wind with the help of hand drill, secured in a table vise. The frame itself will have to be fixed on a threaded rod using two pairs of washers and nuts, and the rod in the drill chuck.
Unfortunately, it will not be possible to set the pendulum in motion using only one electromagnet - you will need two commutators that turn on the electromagnet only at those moments when the armature of the pendulum moves in its direction.
Each of the switches consists of a contact petal made of one-sided foil PCB. The petal is hinged in a duralumin housing and is held in a vertical position using a pair of springs.
The process of switching an electromagnet is shown in the diagram. When the armature moves towards the electromagnet, the contactor mounted on the pendulum rod touches the conductive side of the contact lobe of the first commutator, turning on the power to the electromagnet. The latter begins to attract the armature to itself, but when approaching the center of the electromagnet, the contact petal slides off the contactor, breaking the power circuit, and the pendulum continues to move by inertia. Next on the path of the contactor is the insulated side of the contact lobe of the second commutator, so the contactor will freely deflect it and continue moving until it stops at a dead center, and then swing towards the electromagnet, and halfway towards it the contactor will touch the conductive side of the contact lobe of the second commutator, thereby turning on electromagnet. Well, then the process will be repeated as long as the device is connected to a power source.
That's all, actually.
Assembling the pendulum mechanism is not difficult. The main thing here is to ensure a minimum gap between the armature and the electromagnet (about 0.5 mm) and adjust the position of the contact petals of the commutator relative to the contactor. To set the pendulum in motion, you just need to swing it.
The clock will be indistinguishable from real antique pendulum clocks if two “weights” are suspended on chains behind the glass door - the easiest way to make them is from scraps of duralumin pipes, which should be polished to a mirror shine.
In addition, the accuracy of the perception of a watch will be largely influenced by the care taken in finishing its case.
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