Transistor clock. Scheme, description. Homemade electric pendulum Scheme of a magnetic pendulum for an electronic wall clock
The work is based on the properties of an electromagnet huge amount devices and machines. 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 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 flat board hardwood. 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 top part vertical pillar 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 its side part to the breaker. At the same time electrical circuit will close 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's another one side 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.
Electric swing - good gift 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 of course it is 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’s better to choose a neodymium one, there are plenty of them now, although a regular one will do just fine.
The coil is wound with double wire, each with a cross-section of approximately 0.25-0.3, about 1500 turns, i.e. 2 are taken in parallel copper wires and wind on a reel. 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.
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 school years out of pure enthusiasm based on a scheme 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 soon 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.
The main element of a conventional mechanical watch is a pendulum or balance, which is driven by a weight or spring. Such watches require regular and frequent winding, which creates certain inconveniences.
Many designers worked for a long time on the problem of creating a watch without weights and springs, and as a result, electromechanical watches appeared. In them, the pendulum is driven by an electromagnet, which is powered by a source electric current. When the pendulum approaches the equilibrium position (Fig. 1), the contacts associated with it close and current flows through the electromagnet winding. A soft iron anchor is attached to the pendulum, which is attracted by a stationary electromagnet.
Rice. 1. The device of electric contact clocks.
Electromechanical watches consume battery energy very economically and have good accuracy. But they also have a weak point - the contacts that close the electromagnet circuit. After all, in just one year they have to close millions of times, so after a while electric clocks begin to work inaccurately. And if the watch is very small, for example a wristwatch, then the miniature contacts in them work even more unreliably. With the advent of transistors, it became possible to create contactless electric watches.
Scheme electric contactless watch on a transistor is shown in Fig. 2. A permanent magnet is attached to the pendulum, and when it moves, an emf is induced in the turns of the stationary coil. One of the coil windings is connected between the base and emitter of the transistor, the second is connected to the collector circuit.
Rice. 2. Electrical diagram clock on a transistor.
The center of the pendulum (magnet) intersects the axis of the coil in the equilibrium position. When the pendulum oscillates, an emf is induced in coil L1, the shape of which is illustrated by curve 1 (Fig. 3). In this figure, the curves drawn with a solid line represent diagrams of voltages and currents that arise when the pendulum moves from left to right, and with a dotted line - from right to left. The ends of the winding of coil L1 are connected so that when the pendulum approaches the equilibrium position, a voltage negative relative to the emitter appears at the base of the transistor. It occurs when the magnet approaches the coil, due to an increase in the magnetic flux crossing its turns. At the equilibrium position, the magnetic flux through the coil reaches its maximum. At this moment the tension becomes equal to zero. Then the magnetic flux begins to decrease and the emf changes sign to the opposite. When the magnet moves far from the coil, the voltage at its ends almost disappears. During the second half-cycle, the picture repeats: when the magnet approaches the coil, such an emf is induced in winding L1 that the voltage at the base is negative. Under the influence of this voltage pulse, a current flows in the base circuit (curve 2) and the transistor is unlocked (Fig. 3).
Fig.3. Diagrams of voltage, current and energy of the pendulum for the clock circuit shown in Fig. 2.
A is the amplitude of oscillations of the pendulum,
O - equilibrium position.
The direction of the turns of coil L2, connected to the collector circuit, is such that when the collector current passes through it (curve 3), the magnet is attracted to the coil. His movement accelerates.
The oscillation frequency of a pendulum, as in a conventional clock, is almost entirely determined by its physical parameters: length and mass distribution. The mass of the pendulum is mainly determined by the magnet and its mounting parts. The pointer mechanism is connected to the pendulum with the dial, and the clock is ready.
Clock design. Any pendulum clock or “walker” is quite suitable for making transistor clocks. In them it is only necessary to redo the trigger device and, of course, remove the spring or weight; their functions will be performed by the battery.
In ordinary watches, the escapement device that sets the pendulum in motion has the form shown in Fig. 4, a. It must be redone as shown in Fig. 4, b. A rocker arm 2 is soldered onto the axis 1, on which the shackle 3 is freely suspended. When the pendulum moves to the left, the shackle slides along the beveled side of the tooth of the ratchet wheel 4 and, under the influence of its gravity, jumps off its top into the gap between the teeth. When the pendulum moves to the right, the shackle rests on the steep side of the tooth and turns the ratchet wheel to the left by one tooth. To fix the position of the wheel and prevent it from turning to the right, a pawl petal 5 lies on top of it with one edge. The second edge of the petal rotates freely around axis 6. When the ratchet wheel rotates to the left, the petal slides along the beveled edges of the teeth and, jumping off their tops, rests into the steep edges of the teeth.
Rice. 4. Device trigger mechanism regular watch(es).
The device of a clock mechanism on a transistor for conversion oscillatory motion pendulum into rotational movement of the arrows (b).
The assembled mechanism of a watch made from ordinary “walkers” is shown in Fig. 5. The rocker arm, earring and petal-dog in this watch are made of tin. Any magnet can be used. Its volume should not be less than 3-4 cm 3, since it must hold a load of 100-200 g. The described design uses a ring magnet from a loudspeaker with a diameter of 35 mm. To adjust the movement of the watch, the magnet must be mounted so that it can move up and down. If the clock is in a hurry, then the pendulum (magnet) must be lowered.
Fig.5. Assembled watch mechanism.
Any alloy transistors, for example, type P13-P15, can operate in the clock generator (Fig. 2). The operation of the generator does not depend on the current gain of the transistor. Diode D1 can be used type D7B-D7Zh. Instead of a diode, you can use the emitter or collector junction of a germanium alloy transistor, from which the emitter or collector lead has come off. If the generator (Fig. 2) uses a transistor with n-p-n conductivity, then the polarity of the battery and diode D1 should be reversed.
The electromagnet coil can be wound on a plastic or paper frame with an internal diameter of 20, an external diameter of 48 and a width of 8 mm. You need to wind the coil in two wires until it is full. Wire diameter - 0.09-0.15 mm. After winding, it is necessary to check whether there are short circuits between the resulting two windings. The beginning of one winding is connected to the end of the other and the emitter terminal of the transistor is connected to this point.
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Oddly enough, even in such a huge repository of information as the Runet, you will not soon find serious information on how to do it yourself. Undoubtedly, the simple design of this device will immediately catch your eye. But you will have to look for serious information, an explanation of the principles of its operation. If you typed the phrase “how to make a magnetic motor with your own hands” into a search engine and came across this article, you may have been somewhat lucky. Next - about the features of the work of this device and an example of its simplest model.
The power of such an engine directly depends on the magnetic mass - the stronger the magnet, the more powerful the engine will be. However, this rule is relative. One example can be given - a giant magnet with a volume of cubic meter. Its weight is from 8 to 12 tons. It itself creates a huge force field, so even approaching it is dangerous. By the way, in real life such a phenomenon is practically impossible. Such a magnet is capable of tying the rails of the train that will transport it into a knot, crumpling the car and firmly sticking to it. So what does this example show? On the one hand, the greater the magnetic mass, the better. However, up to a certain limit. Too much magnet mass is a reduction Engine efficiency and additional problems.
When drawing up a device diagram, there are several points to consider. First, the element that is used as the moving part cannot slip through the magnetic field. The driving force arises due to the unevenness of the field - no driving forces in a constant field. Devices operating under the influence of the above phenomenon are ineffective. This must be taken into account if you want an engine permanent magnets with your own hands. The power of such a device depends on a number of reasons. First of all - from closure magnetic field on the working gap, without a magnetic core the efficiency of the design will be very low. Due to the fact that the “free inventors” of the engine often do not take these rules into account, they, as a rule, either fail or their creation works unsatisfactorily. The most important thing in the manufacture of such a device is to correctly determine the driving moment.
Now let’s talk directly about how to make a magnetic motor with your own hands. The reader will be presented with its simplest model. You will need a small magnet made from a rare earth alloy that will main detail designs. The smaller it is, the better. There should be a small hole in this magnet.
By the way, after this experiment the magnet will completely lose its properties, so use one that you won’t mind losing. You will also need wire - thick steel and thin copper. You will also have to choose the right size candle. Use wire to make a base for a swing-pendulum in the shape of an inverted letter P (the base for it should not be wooden). Hang a magnet on it. To do this, you need to thread a thin copper wire.
Hang a regular magnet on the side inside the structure, weaker, so that the small one is drawn towards it, but so that the angle of deflection of the pendulum is small, not enough for the small magnet to touch the large one on the side, but sufficient for the flame of the candle that you place under it to he was not touched when he assumed a vertical position. Be careful when handling the latter. So, you must place the candle in such a way that it is under the small magnet at the moment when it begins to be attracted to the large one.
Fire demagnetizes it, and at the same time it loses its properties, and due to this, the pendulum takes a strictly vertical position. When the small magnet cools, it begins to be drawn towards the large one again. This cycle of pendulum oscillations will not stop until the candle burns out or until it is removed.
To make a more “serious” magnetic motor with your own hands, it is worth studying the diagrams and selecting the parts necessary for this. But it is equally important to know what makes such a device work. Making an engine with your own hands is not so difficult; almost anyone can do it.
Some houses have them - a large antique clock in a polished closet. red wood, 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 electronic 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 reproduction 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. In the pendulum rod, respectively, two cylindrical holes with a diameter of 2 mm are drilled. 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 fastening 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 — return spring centering screw; 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 dead center the pendulum begins to move in the opposite direction, the contactor touches the contact blade of the second commutator and turns on the power supply circuit of the electromagnet.
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 a choke from an old 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 DC 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, fixed in bench 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 body and is held in 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 the current 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 of the 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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