Under the new rules of the road in the sake of safety, drivers of vehicles (especially when driving outside the city) should include the day of the lights But turn them off after a stop often forget If Parking is prolonged, the battery is badly discharged In chains prevent such troubles offer a simple device, which signals that the headlights were left on while the engine is stopped, and also indicates the inclusion of the turn signal Device contains a sound generator transistors (VT1, VT2) and a threshold of the relay (K1, VD1).
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To calibrate, to establish or verify the performance of the radio equipment in the frequency range of 1-75 MHz allows this device. His scheme (Fig. 1) comprises a generator-the”type” with capacitive connection is made to the transistor V1. The oscillator frequency and its harmonics determine the replacement of quartz resonators B1, connected via connectors X1—X3.
In the fourth issue of the journal for the year 1978, published schemes of electric locks with a “secret”. They all work well, but they, in my opinion, there is one drawback: the locks can not be powered from a DC source. I propose a scheme for electronic lock, the key to which is the resistor. Here’s how it works. When the terminals X1 and x2 (see diagram) connect the resistor R2, transistor V1, the base voltage goes negative, opens and relay K1 is triggered.
Chandelier, sconce or a floor lamp in every house. They often burn on several lamps. Do I need it? Not always. And here is the owner of such a lamp becomes involuntary “waster” of electricity. But only because turning off “unnecessary” lights are not available. However, you can add a third wire. But in flats with concealed electrical wiring immediately raises a problem: where to spend it. And that’s where the master comes home… diode.
What is the kit-the fan does not dream to collect small-sized power source? But here everything depends on the power transformer: it-largely determines the dimensions of the power supply. If you try to make a transformer with a minimum size of, for example, with a magnetic core Ш12Х12, provided that the voltage of 220 V, the number of turns of the primary winding will be approximately 7600.
In most of our schools calls still include the old — fashioned way of push-button attendant or watchman. But this process is not difficult to automate. Proposed device designed for this purpose and may be made in the school radio. The block diagram of the device of the machine shown in figure 1. Electronic digital clock serves at a specified time in the actuator control signals. The actuator enables and disables the programming device, which, in turn, in accordance with the schedule of calls includes internal buzzer and external powerful school bell, feeding him the voltage is 220 V.
At first glance, the school gym is the same as thousands of others. But this is only at first glance… Observant person will note here something unusual. On boards and panels, attached to walls, installed button. Hanging above the light Board. The gym class begins with warm-up, and then the class is divided into groups. Students in one group with a small running start then jump at a time, hand hitting the button. While the scoreboard lights up every time the figure is estimation.
The Internet caught the eye diagram of the automatic charger Ni-Cd batteries developed by Yuri Bashkatov. Assembled the circuit on the breadboard — not working. Modeled it on the computer using the program Work Bench. The result is what is shown in the diagram. The device operates as follows. The transistor VT1 (p-n-p) is open if at its base there is a negative potential, which may appear when the VT2 transistor (NPN) open — this, in turn, occurs if the potential at its base is installed with the variable resistor R4 will be 0.3 — 0.4 V higher than on its emitter.
Aquarists usually determine the turbidity of the water in the aquarium, visual manner (“eye”), and beginners don’t change it until then, until it is radiating the smell. However, with the help of an electronic device, which is easy to collect a couple of free evenings, you can control the suitability of water in the tank for future use, with high precision, eliminating the notorious “human factor”. Will benefit from this approach all people and their Pets in the aquarium.