SU1372239A1 - D.c.voltage drop indicator - Google Patents

Abstract

The invention can be used to pre-alarm and alarm the discharge of primary power sources and to reduce the output voltage of secondary power sources below an acceptable level mainly in small-sized portable equipment. The purpose of the invention is to expand the scope of use. The indicator contains a lambda diode (D) 1, which includes field-effect transistors (T) 2 and 3 with pn-junctions, T 7 and the display element 10. D 1 is additionally equipped with a resistive divider 4 consisting of resistors (P) 5 and 6, one 9 // i (L

Description

of which should be variable. By changing the ratio of the values of P 5 and 6, the trigger voltage of the indicator is adjusted, which leads to the transformation of the current-voltage characteristic D 1. In addition, P 9 is entered into the indicator, and between the sources T 2 and 3, resistance 12 can be switched on. lowering the controlled voltage to a value less than the value of the cutoff voltage D 1, the latter opening. The current flowing through P 9 increases, and the voltage drop across it increases. Therefore, there is a redistribution of the controlled voltage between R 9 and D 1. Reducing the voltage on D 1 causes

further increase in current. This leads to an increase in voltage on P 9 and a decrease in the voltage applied to A 1. Bipolar T 7 opens and limits the voltage drop on P 9. The collector current T 7 goes to display element 10, which signals a decrease in voltage permissible level. The monitored voltage starts to rise, and the current on D 1 decreases smoothly, and after locking T 7 in a jump. Thus, a hysteresis loop is formed on the current-voltage characteristic, which eliminates bouncing at the moments when the display element 10 is turned on and off. 1 hp f-ly, 3 ill.

The invention relates to automation and measurement technology and can be used for preliminary and alarm signaling of the discharge of primary power sources and reduction of the output voltage of secondary power sources below the permissible level mainly in small-sized portable equipment.

The purpose of the invention is to expand the field of use by providing adjustment of the lambda-diode pickup threshold and increasing noise immunity by introducing hysteresis.

Fig. 1 shows an electrical circuit diagram of the device; Fig. 2 shows the current-voltage characteristics of a lambda diode for different ratios of resistors (curves 13-15) and in the presence of a limiting resistance (curve 16); FIG. 3 shows the current-voltage characteristic, which explains the operation of the indicator.

The DC voltage drop indicator contains a lambda diode 1 consisting of a complementary pair of field-effect transistors 2 and 3 with pn-junctions and a resistive divider. The sources of the transistors 2 and 3 are connected to each other, and a resistive divider 4, consisting of

From resistors 5 and 6, one of which must be variable, the midpoint of resistive divider 4 is connected to the gate of transistor 3. The gate of transistor 2 is connected to the connection point of the drain of transistor 3 with resistor 6. The connection point of drain of transistor 2 with resistor 5 is connected to the base of bipolar There is a resistor 9 connected between the emitter and the base of the transistor 7. The collector of the transistor 7 is connected to the display element 10. The drain of the transistor 3 is the input 11 of the device. The sources of the transistors 2 and 3 can be interconnected through a resistor 12.

The indicator works as follows.

A controlled voltage is applied between the device input 11 and the common bus 8. If the voltage to be monitored is greater than the cut-off voltage of the Lambda diode UOTC, then the Lambda diode 1 is locked. The current from the monitored source flows through the chain of series-connected resistors 5, 6 and 9. Since the control of field-effect transistors 2 and 3 is potential, the leakage current of the low-power field transistor

The resistor is in the range of tenths to tenths of nanoamperes, the resistance of resistors 5 and 6 can be chosen such that the input current does not exceed the fraction of the microampere. The resistance value of the resistor 9 is selected by several orders of magnitude less than the total resistance of resistors 5 and 6 so that the voltage drop across it is significantly less than the base-emitter threshold voltage needed to unlock the silicon transistor 7. Transistor 7 is locked, the signal display element 10 is not applied. When the monitored voltage decreases to a value smaller than the cutoff voltage of the lambda diode 1, the latter opens, the current flowing through the resistor 9 increases, the voltage across it increases, therefore the redistribution of the monitored voltage between the resistor 9 and the lambda diode 1. The decrease in voltage on the lambda diode 1 causes a further increase in current, which leads to a further increase in the voltage on the resistor 9 and a decrease in the voltage applied to the lambda diode 1. From the moment the abs The lute value of the differential resistance of lambda-diode 1 will become less than the value of resistor 9. (point a, fig. 3), this process will be avalanched until bipolar transistor 7 opens and limits the voltage drop across resistor 9 (curve a b c, fig. 3). The collector current of the transistor 7 is supplied to the display element 10, which signals a decrease in the voltage below the permissible level.

If the monitored voltage starts to rise after the indicator is triggered, then the current of the lambda diode 1 will decrease first smoothly to point d (Fig. 3), and after the transistor 7 is locked with a jump (right d e, Fig. 3). So at volt am

five

from 5 0

0

five

0

five

0

A first characteristic is formed by a hysteresis loop, which eliminates bouncing at the moments when the display element 10 is turned on and off.

The adjustment of the operating voltage of the device is made by changing the ratio of the values of resistors 5 and 6, which leads to the transformation of the current-voltage characteristic of lambda diode 1 (curves 13-15, figure 2).

Claims (2)

1. The DC voltage drop indicator, containing a bipolar transistor, the emitter of which is connected to a common bus, and a collector with an indication element, is connected to the base of the bipolar transistor by a lambda diode consisting of a complementary pair of field-effect transistors whose sources , the gate of the first field-effect transistor is connected to the drain of the second field-effect transistor and to the indicator input, the drain of the first field-effect transistor is connected to the base of the bipolar transistor, characterized in that, in order to increase the noise immunity By introducing hysteresis and expanding the range of use by providing adjustment of the lambda-diode trigger threshold, a resistor and a resistive voltage divider are introduced in it, one arm of which is adjustable, the extreme terminals of the resistive voltage divider are connected to the drains of field-effect transistors, and the average the output is with the gate of the second field-effect transistor, the resistor is connected between the base and the emitter of the bipolar transistor, 2. The indicator according to claim 1, characterized in that, in order to expand the use area by reducing the energy consumption, a second resistor is inserted in it, which is connected between the sources of the first and second field-effect transistors. , 73 / Vsffjf orc FIG. 2 V 6l Fig.z