To radio sounded good on the UHF band, it should be adjusted to exactly take the radio. Will help you with this indicator fine adjustment circuit of which offers Bulgarian journal “Radio Television Electronics”.
That fuse in the radio, will alert you to the simple automatic device, scheme of which was published the magazine “Radio Fernsehen Elektronik” (Germany). While a fuse F1 (see figure), the voltage between the emitter and base of transistor V1 is equal to zero and a semiconductor device is closed. Once the fuse will burn immediately on the basis of V1, a voltage is applied, opening the transistor and the led B1, included in the collector circuit will light, indicating an “accident”.
The creation of remote electronic devices control various actuators were promising direction in the radio even during my “pioneer” childhood in the 1980-ies. Then, under the guidance of mentors, we enthusiastically gathered such equipment using discrete components. She usually had a range of 5 — 6 m and it barely fits in the box size 300х300х150 mm. If it was possible to assemble at least a fortnight instrument remote control model boats or aircraft with a transmission range of teams at 20 — 30 m, it was considered from us (10 to 12-year-olds) with great success.
Motorists made electronic blocks of ignition, as a rule, according to the classical scheme consisting of a high voltage source, a storage capacitor and a thyristor key. However, such devices have several drawbacks. The first of them is low efficiency. Since the charge storage capacity can be likened to the charging of the capacitor through a resistor, the efficiency of the charging circuit does not exceed 50%. So, about half consumed by the power Converter will be allocated in the form of heat” on the transistors. So they need more heat sinks.
Beginner ham radio production of “solid” light and music installation on the thyristors — it is difficult to implement. The scheme is simple SMU, not containing thyristors, offers the magazine “Funkamater” (GDR). The device can be connected as a mono and stereo; for that purpose, two identical input stage transistors V5, V6 (see diagram). They are connected with a three-band crossover.
Recently Russia adopted a law allowing drivers to get behind the wheel of a car with a small residual content of alcohol in the blood. Knowing how topical this subject in Russia, I think it is important to highlight some technical aspects of control (and self control) persons who consumed alcohol. Of course, the objective of this study is not in dispute is that the law or the causes of the problem. Below we consider the technical issues on breath alcoholic couples. But first, let’s look at the history and production technology of industrial sensors of various vapor and impurities in the air. In many European countries (Germany, Finland, Poland and others) a few years ago appeared in the free sale breathalyzer, or so-called “alcohol vapor detectors” (Roadtest).
Conventional Bicycle bell has a number of disadvantages: inconvenient to work with, rattles while driving even on a flat road makes a sharp, unpleasant sound.
Every radio Amateur knows that without a source of constant and alternating stresses of different magnitudes in practical work is not enough. He needed to establish radiocontrole, repair equipment, charge batteries, test the motors and relays, to conduct physical experiments. All this is possible to do with a universal power supply, which we offer to the readers.
In this case doctors usually recommend to warm up the area of nose and the bridge of the nose with bags of hot sand or a medical reflector. But here’s the problem: the bag has to hold hands and to periodically change the sand cooled and the heat from the reflector heats not only the nose but the whole face, and even the light from the lamp is blinding. Heating pads, too uncomfortable — too big. But perhaps the most significant drawback of all mentioned devices is the inability to smoothly adjust the heating temperature.
It is used in teaching music in rhythmic gymnastics, in experiments in physics etc. a Metronome, a scheme which offers Bulgarian journal “Radio Television Electronics” (see Fig.), gives not only audio but also visual signals. With the help of variable resistors R1, R2 their frequency change in the range of 40 to 200 cycles / min. which corresponds to the musical pace from “grave” to “Prestissimo”.