Usually automatic device switch on and off the Christmas tree lights in leaps and bounds, without changing the brightness. But the electronic switch scheme is presented in figure — does not have this drawback. The basis of his work is based on the principle of beats that occur between the frequencies of the mains and generator. The latter is a multivibrator transistors T1, T2. It generates rectangular pulses with a frequency of (100 ± Δ) Hz (100 Hz is the fundamental frequency of the multivibrator, And the frequency of the beating, which switch lamp garland which is in the range of 0.1—8 Hz). Adjustment of the burning time of the lamps is variable resistor R6 “Smoothly” and R7 “Rough”.
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We offer a simple pocket radio with low voltage power from the supercapacitor. The receiver is fully on transistors, because the low voltage does not allow to use the existing chips (e.g., 174ХА10). Receiver of direct amplification, which provides sufficient volume to broadcast stations in the medium waveband and working in a range of supply voltages from 2 to 0.9 V.
The proposed device allows you to charge any rechargeable batteries with voltage from 1.2 to 15 V and a nominal capacity of from 0.05 to 20 A·h and can be widely used in radio, car owners and even users of electronic equipment. The device is a charger (current stabilizer), which uses a pulse-frequency regulation, which eliminates the need for bulky heat sink from the control transistor.
In the “M-K” appear frequently describe designs that use integrated circuits. The production of these modern elements are so expanded that their widespread introduction in household equipment and in the development of ham radio now is no surprise. However, there still exists an opinion that “communication” is with chips only available to experienced hams. Meanwhile, in the chips can be used to create simple devices to collect that it is easy even for those who make their first steps in Amateur radio.
Small disk batteries are widely used in electronic equipment and in ham radio construction. But to charge them is not easy. Then stir and pure design features: the differences in the size of the disk batteries, no special conclusions for reliable connection to the external circuit and connectors between the individual elements in the batteries. In addition, it is necessary to control the magnitude of charging voltage and current using electrical appliances.
CHARGING AND RECOVERY DEVICE’S BATTERY. The battery in the car is one of the most important elements. Despite the constant efforts of manufacturers to improve the reliability and durability of the batteries after 3 — 4 years they still come into disrepair, aided by a constant undercharge when riding in urban environments the cost of the battery remains high, so to extend the term of its service makes sense at least once in the summer season to carry out remedial exercises.
The light on the dash must have heard many. A pistol or shotgun just like the real thing, the rings of a target with a ten in the middle. Yes, but “bullets” are not the same. Pulled the trigger and the target affects short flash of light. And the brighter dalnoboynie weapon. The light beam of the flash lamp to “shoot” at a target even from a distance of 25 m. This corresponds to one of the distances sports bullet shooting.
Fluorescent light (LDS) are widely used today in various industries and in everyday life. Unfortunately, the durability of LDS is extremely low. Their weak spot — helix required for the ignition of the phosphor inside the lamp at the time of inclusion. Two of them — from both ends of the lamp, and if even one of them burn out, to include LDS with the standard circuit (containing inductor, capacitor and starter) is impossible. In such a situation it is necessary to change the blown bulb with a new one. Therefore, where there are a large number of lamps (for example, in manufacturing plants, apartment buildings, stairwells and other similar cases), during the years of operation goes down and accumulates a lot of LDS with blown spirals.
This switch Christmas garlands periodically includes four groups of lamps. The switching frequency can be changed within wide limits by the variable resistor R5 (see diagram).
Simple dual-band receiver of direct amplification on a hybrid chip К237ХА2 can collect even a novice hobbyist. Moreover, the sensitivity and selectivity it even higher than the equivalent discrete components. And to make it easy.