“Ah, summer red, I would love you, if not for the heat, and dust, Yes mosquitoes, Yes flies”. And although the high poetry of the great poet little combined with the dry prosaic lines, technical articles, these words can be safely put as the epigraph to this material. To stop the change of seasons in nature is impossible, and every year we have a “happening” summer, and with it come the usual worries of relief and localization of negative emotions, invariably manifested in humans with the appearance of annoying flying insects — mosquitoes, flies and other midges. To protect yourself from them, in nature and even at home someone buys a mosquito net, others treat themselves and family members with special insect repelling creams and formulations. However, possessing the skills, you can build a simple circuit protection device against mosquitoes, operating by using of ultrasonic radiation. What is ultrasound?
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If you doubt the validity of a diode, transistor or want to determine their conductivity type, use one of the devices with which we introduce you in this article. The advantage of the devices is simplicity: they can even build a new ham. The basic design is based on schematics from the Bulgarian journal “Radio television electronics”.
Sometimes the output current in the power supply can be increased up to a critical value (due to the increase of power consumption, faulty connections or load devices), which will inevitably lead to the accident consequences of overload can be significant and even irreparable if you use a power supply without the security host (like today often make hams, making simple sources and buying cheap adapters) for Example will increase power consumption, can lead to failure of network transformer, it is possible to separate fire elements and odor.
The device is assembled on the proposed scheme allows to control the power consumed from the DC voltage source. Indication power led is a color display and sound. When using in-vehicle device control the power consumption of lighting devices and additional equipment replaces the voltmeter, connected in parallel with the battery.
The temperature of the soldering iron usually adjusted using Later. However, such devices are bulky, inconvenient for transportation. Significant benefits in this respect have electronic regulators. Thyristor controller — scheme presented in figure 1 — changes AC voltage at the electric soldering iron with power up to 50 watts 110 to 220 V.
Nine Eagles Galaxy Visitor 2 – a miniature copy of the legendary DJI Phantom quadrocopter, has no analogues in its class. The best engineers of the famous company proudly presented model, at small sizes has a number of features previously available only for the serious techniques of the professional level. The Galaxy Visitor 2 has functions such as hold the direction of flight, regardless of the spatial position and automatic return. Because of this quadcopter is not only simple and affordable for beginners – every pilot will appreciate the ability to save models with a complete loss of spatial orientation. Now at a great distance, You can easily capture footage! You like a spectacular night flights? An elaborate illuminated housing ensures excellent readability in the dark.
The proposed device is designed for “soft” on various radio and electrical household AC voltage of 220 V it is Known that the moment of switching devices containing a primary or secondary power circuits the capacitors of large capacity (high power audio amplifiers, switching power supplies and other devices), accompanied by a cast of current, which can reach tens of amperes.
In Amateur practice it is often required to provide an audible alarm, activated when the lighting of any object, the device responds to sudden illumination luminous flux working (photosensitive) surface of the photoresistor.
Probably you are familiar with simple electrical device for training “the steadiness of the hand” — a metal panel with a narrow winding slot, along which, without touching its edges, it is necessary to hold the pivot-pin. One careless touch probe to the edge and flashes the warning light. Such devices form the basis of the various attractions and special equipment. This principle is valid for our slot machine.