SU859996A1 - Threshold device - Google Patents

Description

one

The invention relates to automation and measurement technology and is intended for use in devices for simulating the movement of a channel stream when switching resistors in a block modeling the hydraulic characteristics of a river bed.

A threshold device is known, consisting of an input transistor, in the collector circuit of which a resistor is connected, and parallel to the collector of the input transistor are connected in series two resistors, one of which is bridged by a capacitor, and the second is connected to the base of the output transistor and the zero potential bus. In this case, a resistor is connected to the collector of the output transistor. The emitters of the input and output transistors are connected and connected to a resistor connected to the zero potential bus 1.

The disadvantage of such a trigger is a large hysteresis loop, low initial sensitivity, which makes it impossible to use it in circuits for simulating the movement of a Russian flux, where the output impedance of the input source

varies widely, the hysteresis loop should be as small as possible, and the initial sensitivity should be large. This is especially the case when a relay coil is connected to the collector of the output transistor instead of a resistor. The closest in technical essence to the proposed is

10 is a threshold device made of an input key transistor, in the collector circuit of which a resistor is connected, and parallel to the collector there are two series-connected resistors, one of which is shunted by a capacitor, and the second is connected to the base of the zero potential. In the weekend collector

20 key transistor included resistor. In addition, two resistors are additionally included in the emitter of the output key transistor, one of which is connected to the emitter of the input

25 transistor. In this device, the loss of the hysteresis loop is achieved by the fact that parallel to the resistor, which is mapped to the emitter of the output transistor, is additionally included

Claims (2)

30 are connected in series, one of which is connected to the emitter of the output transistor 2. A disadvantage is the difficulty of using this circuit when the difference between the resistance connected to the collector of the input transistor and the resistance connected to the collector of the output transistor is large enough. Such a circuit gives satisfactory results when quite large resistors are included in the collectors of the transistors. The resistance of the resistor (included in the emitter of the input t-anistor, also should not be too small. Therefore, with the existing difference between the resistance of the collector resistor of the input transistor and the low resistance of the relay coil, BKjpo4ae to the collector of the output transistor, the difference between the values of the resistance included to the emitter of the input and output transistor, may be quite certain. This limits the possibility of using such a device in case of replacing a resistor in the collector: output transistor The purpose of the invention is to eliminate this drawback in a threshold device with a relay, namely, to increase accuracy by reducing the width of the hysteresis loop. The goal is achieved by the threshold device containing the input key transistor whose base is connected to the input of the device, the output of the bias voltage divider and through the limiting diode to the zero potential bus, and the collector is connected via the first limiting resistor to the supply voltage and the output key transistor The op, the collector of which is connected in parallel to the coil of the relay and the shunt diode is connected to the supply voltage, the base is connected to the output of the voltage sharing on the resistors connected between the collector of the input key transistor and the zero potential bus transistors through an additionally connected second limiting resistor and the heat compensating diode are connected to the zero potential bus, an additional voltage divider on the resistors is inserted, including ny between the collector of the input transistor and ground potential bus, to yield torogo connected to the base of the input transistor chevogo key again. The drawing shows the device. The threshold device contains a bias voltage divider, performed on resistors 1 and 2, which set the source voltage to the base of the second key transistor 3, limiting diode 4, limiting the value of the positive voltage at the input of the device, an additional voltage divider on the resistor 5 connected with the base of the input transistor 3 and resistors 6 and 7, the limiting resistor 8 connected to the collector of the input key transistor 3, the voltage divider on resistors 9 and 10, in which the resistor is connected to the collector input th transistor 3 and the resistor 10 is connected to the base of output transistor 11. The collector of transistor 11 includes a relay coil 12 shunted by a diode 13, the emitters of transistors 3 and 11 are connected to a limiting resistor 14 connected to a thermal compensating diode 15. A diode 15 serves to compensate for the temperature drift of the thresholds of actuation and release of the device. The device works as follows. In the initial state, the transistor 3 conducts an electric current, the transistor 11 is locked. Since transistor 3 is open, the voltage between its emitter and collector is very small, so the voltage supplied from the collector of transistor 3 to its base is also very small and plays little or no role. When the transistor 3 is locked, transistor 11 opens. In this case, a voltage drop is created on the resistor 14, but it is larger than in the case when transistor 3 was open. Since resistors b and 7 are connected to the collector of transistor 3, when it is locked, a negative potential is applied to the base of transistor 3. At the same time, the potential difference between the base and the emitter of the input transistor is reduced, but it is not sufficient for this transistor to open. The magnitude of the voltage supplied to the base of the transistor 3 can be adjusted within very wide limits, while the hysteresis loop is regulated and the initial sensitivity of the circuit. When the transistor 3 is opened, the circuit returns to its original state. The use of the proposed threshold device with a relay distinguishes it favorably from the known one, since it does not require two or more power sources, makes it possible to use any type of relay, set the required hysteresis loop or reduce it to as little as possible 1 value. In this case, the initial sensitivity of the circuit can be very high without additional efforts of the input signal. The invention The threshold device containing the input key transistor, the base of which is connected to the input of the device, the output of the bias voltage divider and through the limiting diode to the zero potential bus, and the collector through the first limiting resistor is connected to the power supply, and the output key transistor, the collector of which through a parallel-connected winding of the relay and the shunt diode is connected to the supply voltage source, the base is connected to the output of the voltage divider on the resistors, including between the collector of the input key transistor and the zero potential bus, the emitters of the input and you; input key transistors are connected through the second limiting resistor and thermal compensating diode to the zero potential bus, in order to increase accuracy by reducing the width of the hysteresis loop ; a voltage divider across the resistors connected between the input capacitor of the eich transistor and the zero potential bus is entered into it; orogo connected to the base of the input transistor. I Sources of information taken into account during the examination 1. Stepanenko I.P. Fundamentals of the theory of transistors and transistor circuits. M., Energie, 1973, p. 481-487. 2. To help the radio amateur. Issue 52 publishing house DOSAAF, 1976, p. 73-77 (about | TOTIP). - (-c ± srn