Broadcasting prefix to the tape recorder. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Broadcasting prefix to the tape recorder. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / radio reception

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If you have a tape recorder or player, you can receive broadcast radio stations in the MW range by connecting an RF prefix to their amplifier, the circuit of which is shown in the figure.

Radio broadcaster for tape recorder

A feature of the device is high sensitivity, achieved through the use of positive feedback (circuit L3C4), and a kind of inclusion of transistors in the RF amplification stage. The choice of the optimal feedback value is made by selecting the number of turns of the coil L3 and changing the capacitance of the tuning capacitor C4. The operation mode of transistors (T2 in the OE circuit and T1 in the OK circuit), having a common load and series power supply (resistor R3), improves the amplifying capabilities of the cascade. The sensitivity is approximately 1 mV/m over the entire received frequency range.

The antenna coil L1 has winding data for the MW range of a pocket receiver (50 turns of PELSHO 0,1 wire). Coil L2 - 2..4 turns.

The LF output stage on the T3 transistor makes it possible to connect the prefix to any LF input stage. The current consumed by the device is about 1 mA.

In the console, you can use almost any high-frequency transistors, for example, P403 or GT309V in the first stage and low-frequency transistors such as MP40 in the output stage. The selection of their modes should be made by changing the resistance of the resistors R1, R2 and R6. As a diode D1, it is possible to use a diode of the D9V type.

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In a dream, the brain sees something new 24.08.2015

Our sleep is divided into slow and fast phases, and fast is also called REM sleep, where REM - rapid eyes movement, rapid eye movements. It is usually said that at this moment we are dreaming, and the eyes move along with the pictures that are rushing through the sleeping brain. However, there was no direct evidence of this - until today.

Neurobiologists from Tel Aviv University, the University of California at Los Angeles and the University of Wisconsin Madison involved 19 patients with epilepsy who were about to undergo surgery. Before removing the part of the nervous tissue that causes seizures, the patient was injected with electrodes, which were supposed to indicate where, from which neurons the epileptic seizure begins. Usually in such cases, some fundamental research is carried out in parallel with the medical procedure, because this is a unique opportunity to look into the living human brain.

Itzhak Fried and colleagues tracked the activity of individual nerve cells in the middle temporal cortex, where the transition between visual perception and memory occurs. The local neurons react both to a new picture and to what we already know (for example, to photos of friends or places we have visited), and, in the second case, it is not even necessary to look at the photo, just close your eyes and see something familiar , stored in memory, "mind's eye". The nature of neuronal activity in both cases is different. The work of nerve cells was recorded when a person was sleeping, when he woke up and lay in a dark room (and did not see anything), and when he watched some kind of video and communicated with people. In a separate test, a volunteer was asked to fix their eyes on something in order to understand how neurons behave when their eyes are fixed.

And it turned out that during REM sleep, neurons work as if the brain saw something new - as if we, awake, went into a place completely unfamiliar to us. In sleep, nerve cells fired exactly after the next eye movement, so it can be argued with great reason that the work of the eyes and the work of neurons are really connected with each other. The results of the experiments are described in an article in Nature Communications.

These data, in a sense, contradict the point of view according to which unconscious work is done in the sleeping brain with images that fell into memory while we were awake. To reiterate, neurons work just as they do in reality, and "see" not something familiar that might come from memory, but something new. But here, however, there are too many ambiguities and pitfalls to draw global conclusions.

First, what does "new" and "old" mean? Maybe a combination of old images gives a new visual sensation? If the cells really react to something new, then where does it come from, with their eyes closed? And, finally, and most importantly, although we believe that rapid eye movements in a dream indicate a dream, there is no strict evidence for this. That is, we do not know why the eyes move, whether this is a reaction to dreams.

According to some assumptions, dreams generally refer to the moment when we are just falling asleep or when we wake up, and they represent signals reaching the half-asleep brain from the outside. It remains to be hoped that further research will help us understand what happens to consciousness during the transition from wakefulness to sleep and vice versa.

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