Low voltage voltage regulators. Encyclopedia of radio electronics and electrical engineering
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The output voltage of the stabilizer, in which a bipolar silicon transistor is used as a reference voltage element ("Radio", 1972, No. 6. p. 18) is 1,0-1,3 V. Sometimes, it is necessary to have an even lower stabilized voltage. In this case, germanium transistors can be used in the mentioned two-terminal network instead of silicon ones (Fig. 1). The operation of such a two-terminal network was tested by Roznatovsky on five pairs of MP38 and MP39B transistors, the parameters of which were not previously measured. The smallest dynamic resistance of a two-terminal device with these transistors is achieved with the resistance of the resistor R1 in the range of 15-17 Ohms.
Ris.1
From the one shown in Fig. 2 of the average current-voltage characteristic of a two-terminal network, it can be seen that the voltage value Ust remains within 0,35-0,01 V when the current changes from 4 to 14 mA. that is, the dynamic resistance of a two-terminal network has a value of 1-2 ohms. The temperature stability of the voltage at the terminals of the two-terminal network under consideration is, of course, worse than that of the two-terminal device on silicon transistors.
Ris.2
It is possible to feed amplifiers and generators on tunnel diodes through a voltage regulator, the circuit of which is shown in fig. 3. By changing the resistance of the variable resistor R1, you can change the voltage at the base of the transistor T1 and thereby set the voltage at the output of the stabilizer Uout within 0,15-0,3 V at the load current Iout<50 mA. The output resistance of the proposed stabilizer is 0,3-0,6 Ohm, the stabilization coefficient is about 3,6 at the input voltage uin=4,5 V. As can be seen from the diagram, the output voltage uout corresponds to the voltage at the emitter junction of the transistor T2. When the load changes, the base mode of the transistor T2 changes, which leads to a change in the electrical conductivity of the collector-emitter section of this transistor and compensation of the perturbation.
Ris.3
On fig. 4 shows the adjusting characteristic of the stabilizer Uout (Iout) and the curve n (Iout), where n = Iout / Iin.
Ris.4
From this graph it can be seen that the stabilizer according to the scheme in Fig. 3 is highly economical. The input current of the stabilizer is only 0,5-1,5 mA more than the load current. When using P416 transistors in the stabilizer, a slightly higher output voltage is obtained (obviously, in this case, the polarity of switching on the input voltage source must be reversed, compared to that shown in Fig. 3).
Authors: A.Roznatovsky, L.Vsevolozhsky, Yu.Sivogin
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Our emotions are most easily identified by facial expressions and voice. However, there are as many faces and voices in the world as there are people, and how can we be sure that some kind of emotional grimace in different people expresses the same thing - for example, fear, or joy, or sadness?
In fact, there is no problem for you and me here, our psyche easily copes with the variety of features of someone else's appearance and easily singles out common emotional components in facial expressions. The same thing happens with the voice. However, if we set out to teach a robot to recognize emotions, then we will need clear criteria by which the machine could distinguish fear from joy, and joy from sadness in any of their intensity, with any shades and on any faces.
Researchers from the Islamic University of Technology in Bangladesh chose an original way to solve this problem: they focused not on facial expressions, but on the fingers. The emotion recognition program had to focus on how a person types on the keyboard. In the first part of the experiment, 25 volunteers aged 15 to 40 retyped a piece of text from Lewis Carroll's Alice in Wonderland, while noting their emotional state: joy, fear, anger, sadness, shame, etc. If certain emotions are not it was, you could choose fatigue or neutral emotions. (It is clear that emotions could be in no way connected with the text, a person could be typing, being influenced by some of his thoughts and feelings.)
In the second part of the experiment, volunteers were already typing something of their own, but every half hour they were reminded of a certain emotion: sadness, shame, fear, joy, and further down the list - they had to enter this emotional state and stay in it while typing. At the same time, a special program collected information about how users click on the keyboard buttons.
In an article in Behavior & Information Technology, the authors of the work write that they managed to identify 19 key parameters that could be used to judge the emotional state of the typist. Among them were, for example, typing speed in an interval of five seconds, and the time during which the key remained pressed. Parameter values measured on free text were compared with standard values for specific emotions and words, which were obtained using Carroll's text. In this way, as the researchers will assure, it is possible to determine seven different emotions with great certainty. Most likely, they succeeded with joy (the correct answer was in 87% of cases) and with anger (the correct answer was in 81% of cases).
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