SU1182437A1 - Digital resistance meter - Google Patents

Abstract

A THERMAL RESISTANCE SURVIVOR, including a digital indicator, connected by an anode through a resistor to a power source, (N-1) transistor switches (where N is the number of bits of a digital indicator), each of whose collectors is connected to one of the digital indicator cathodes, characterized in that For the sake of simplicity, it is equipped with an additional two voltage dividers, each of which consists of N series-connected resistors, the junction points of which are the outputs of voltage dividers, three current generators and ( N-1) cascode-connected transistors, in which each emitter of the previous one is connected to the collector of the subsequent transistor and to the emitter of the corresponding transistor switch, the collector of the first transistor is connected to the low-order digit of the digital indicator, the first output of the first current source, the second the output is to a common point, the first output of the second is (L voltage, connected to the output of the second current generator, and the second output is the input of the device, the output of the third current generator connected to the point of connection of the emitter of the last transistor and the emitter of the last transistor switch, with the output of the first voltage divider connected to the base of one of the corresponding transistors, and each output of the second de-SO switch is connected to the base of one of the corresponding transistors.

Description

one

The invention relates to a measurement technique, in particular, devices for measuring resistances and can be used to directly measure the resistance value or any non-electric quantity converted to a change in resistance.

The purpose of the invention is to simplify a device for digital resistance measurement.

The drawing shows a schematic diagram of a digital resistance meter

The device contains a digital indicator 15 which through a resistor 2 is connected to a power supply voltage (Eg) and high-voltage transistor switches 3-12, the collectors of which are connected to the cathodes of the digital indicator 1. Additionally introduced cascode-connected transistors 13-22 are connected to the outputs of the voltage divider, consisting of resistors 23-33, and the points of connection of emitters and collectors - to transistor emitters: switches 3-11, the bases of which are connected to the outputs of the second divider, consisting of resistors 34-44. A first voltage divider from resistors 2333 is connected between the device input 45 and the first current generator 46, and a second divider from resistors 34-44 is connected between the common bus and the second current generator 47. Emitters of key 12 and transistor. 22 are connected to the output of the third current generator 48.

The device works as follows.

The base voltage of high-voltage transistor switches 3-12 are supplied by the reference voltage UQP from the voltage divider from resistors 34-44 with a step change uUon greater than the voltage change step A J. supplied from the voltage divider codes from resistors 23 -33 to the base of cascade-connected transistors 13-22. As a result, in the initial state, when the value of the measured resistance connected between the device input 45 and the common point is zero, all transistor switches 3-12 are closed, and the cascade-connected transistors 13-22 are open. Current general372

The torus 48, equal to the rated current of the digital indicator 1, passes through all of the cascade-connected transistors 13-22 that are in a conducting state and causes the zero electrode of the indicator lamp to glow.

Pitch ilJoj, and lhrd, is set by the resistors of the dividers, respectively

34-44 and 23-33, through which the currents of the generators 46 and 48 flow.

In this case, the value of & UcM should be no less than the saturation voltage of the included cascade transistors with

so that the transistors 13–22 are in the conducting state. The difference, & Uj, determines the sensitivity of the device, which should exceed the switching voltage of the transistor switches 3-12 for a clear indication switch. digital indicator lamps 1

With an increase in the measured resistance 49, the voltage on the bases of the cascade-connected transistors 13-22 increases in proportion to the magnitude of the measured resistance.

When the voltage at the base of the transistor 13 exceeds the voltage by

base transistor switch 3, transistor 13 closes and transistor switch 3 opens. As a consequence, the digit O goes out and the digit 1 of the indicator lights up.

A further increase in the measured resistance 49 leads to an excess of the reference level at the base of the voltage transistor 14 supplied from the divider (34-44) to the base of the key 4.

This causes the switching of the transistor 14 and the key 4 and the change of the digit 1 to the digit 2. The digit 1 goes out as the transistor 14 goes to the non-conducting state and interrupts the current

through key 3, although the latter continues to remain open.

If the resistance value 49 continues to increase,

successive unlocking of transistor switches 5, 6, ..., 12 and locking of transistors 15, 16, ..., 22. On indicator 1, the numbers 3,4, ..., 9,

zap one A comma indication indicates an overflow indicator.

Claims (1)

DIGITAL RESISTANCE METER, including a digital indicator connected by an anode through a resistor to a power source, (N-1) transistor switches (where N is the number of bits of the digital indicator), each of the collectors of which is connected to one of the cathodes of the digital indicator, characterized in that, for the sake of simplicity, it is additionally equipped with two voltage dividers, each of which consists of N series-connected resistors, the connection points of which are the outputs of the voltage dividers, three current generators and (N-1) to of connected transistors, in which each emitter of the previous one is connected to the collector of the subsequent transistor and to the emitter of the corresponding transistor switch, the collector of the first transistor is connected to the lowest digit of the digital indicator, the first output of the first voltage divider is connected to the output of the first current source, the second output to the common point , the first output of the second voltage divider is connected to the output of the second current generator, and the second output is the input of the device, the output of the third current generator is connected to ochke compound latter emitter transistor and the emitter of the last transistor switch, each output of the first voltage divider connected to the base of a respective emu'tranzistornyh * key, and each output of the second divider - to the base of one of the transistors corresponding thereto.