Radio, about which we tell, collected under the scheme direct gain works in long ranges (2000 — 740 m or 150 — 400 kHz) and medium (200 — 550 m or 520 — 1600 kHz) waves. Despite its relative simplicity, it has a sensitivity sufficient for admission to the internal magnetic antenna stations, remote distance up to 250 — 300 km With outdoor antenna reception range even more.VARIABLE RESISTORS WITH TAPS
often need Amateurs with a passion for designing low-frequency amplifiers. But in the sale they are not always. The solution? To make a simple potentiometer with taps. For this it is necessary to remove the cover and remove the axle with the slider. Then with an awl to puncture the plastic covering the hole in Read more…
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
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 recent years, and became noticeable interference in a household outlet, requiring protection home electronic equipment TVs, home audio, computers. These impairments lead to “tearing” of the image on the screens, heard the clicks and POPs from the speakers, “sboyat” digital devices. It is especially annoying when this happens while recording any programs.
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).
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.