SU1442934A1 - Device for measuring time constant of parallel rc-circuit - Google Patents

Abstract

The invention relates to electronics and can be used to measure capacitances, resistances, as well as the time constant parallel to the KS circuits. The aim of the invention is to increase the accuracy and speed of the RC time constant meter. Due to the introduction of the switch 6, the counters 2, 7, 14, the block of comparison of codes 9, the triggers 1 and 13, a sequence is searched for the durations of the pulses of the transistor 11 until the amplitude of the current pulse of the capacitor 17 reaches the value of at which the pulse amplitude control unit triggers. The pulse from the output pulse stops the passage of the pulses from the generator 5 to the counter 7, in which the code of the time interval corresponding to the measured time constant is generated by this moment. In addition, the device contains an indication unit 3, a power supply unit 4, resistors 8, 10, 16, a diode 15. 1 Il. S

Description

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The invention relates to electronics and can be used to measure capacitances, resistances, as well as the time constant of parallel KS circuits,

The purpose of the invention is to increase the accuracy and speed of the time constant meter of the KS circuit.

The drawing shows a block diagram of the device.

The device contains a trigger 1 mode, a counter 2 delays, a display unit 3, a power supply unit 4, a generator 5

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in which the switch 6 is switched to the first output, zeroes in the time counter 7 and the search counter 14 are written down, the output of the code comparison block 9 is a logical unit, the transistor 11 is open, the stop trigger 13 is set to zero. The pulses from the output of the generator 5 through the first output of the switch 6 is fed to the input of the counter 2 delays. The latter is designed to form a fixed delay during which the capacitor 17 of the KS circuit is charged up to the initial voltage 10

rectangular impulses, commutator 6,15 wedge determined by the ratio

a time counter 7, a first resistor 8, a code comparison unit 9, a second resistor 10, a transistor 11, a pulse amplitude control unit 12, a stop trigger 13, a brute force counter 14, a diode 15, a KS circuit resistor 16, a KS circuit capacitor 17.

The first output of the second resistor 10 is connected to the base of the transistor 11, the collector of which is connected to the first output of the first resistor 8 and the input of the pulse amplitude control unit 12, and the emitter is connected to the anode of the diode 15, the second through the first resistor B is connected to the power supply 4, 30 fight, at the output of block 9 comparison the comformational input of switch 6 is connected to the output of generator 5, the first control input of switch 6 is coy; it is connected to the output of mode 1 trigger, summing up with the input of time counter 7 and the reset input of brute force counter 14, the second pack The main input of the switch 6 is connected to the output of the trigger 13, the first output of the switch 6 is connected to the input of counter 2, the second output of the switch is connected to the summing input of the brute force counter, the first input of the trigger 1 mode is connected to the output of the delay counter, its second input is connected with the output of the code comparison unit 9 and the second output of the second resistor 1.0, the stop trigger 13 input is connected to the output of the amplitude 1 control unit 12 of pulses, the first time counter output is connected to the first input of the code comparison unit 9, second th output - with display unit 3, iterate counter output 14 is connected to a second input of the comparator 9 codes.

The device works as follows

In the initial state, the mode trigger is set to the zero state.

the resistance values of the resistors 8 and 16. With the falling edge of the pulse generated at the output of the last bit of the counter 2 delay, the trigger 1 of the mode is shifted to the opposite state. In the counter 2 delays, at this moment a zero state is set.

When the trigger 1 transitions from zero to one, the brute-in counter 14 is reset to zero and one is added to the counter-7 time. Since the contents of counters 7 and 14 are not equal between

The zero state is set and the transistor 11 is closed. The diode 15 turns out to be closed by the charging voltage accumulated on the capacitor 17. The latter begins to discharge through the resistor 16.

In the case of a single state of the mode 1 trigger, the switch 6 is switched to the second output, from which pulses come in, each of which increases the brute force counter by one. .

As soon as the contents of counters 7 and 14 are compared, and in the first cycle this occurs after the first pulse from the second switch code, the output of the code comparison block 9 performs a transition from the zero to one state, while the trigger 1 of the mode is shifted to zero condition. Transistor 11 opens and a capacitor 17 capacitor 17 begins to flow through it, forming a voltage pulse on the collector of transistor 11. If the pulse amplitude is less than the threshold level of the response of the pulse amplitude control unit 12, then at its output it is 10

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a pulse is not generated and starts-, with a new similar cycle.

The new cycle differs from the previous one (due to the fact that the contents of time counter 7 are increased by one level difference from the output of trigger 1 and it takes longer to fill counter 14 to the value of counter 7. The discharge time of capacitor 17 is increased, and the residual voltage on it is correspondingly reduced.

Thus, a sequential search of time intervals is carried out until the amplitude of the capacitor dose pulse reaches a value at which the amplitude control unit 12 controls the impulse amplitude and the output pulse is set to the stop trigger unit 13. At this moment, the passage of pulses through the switch will stop, and in the time counter 7, the time interval code will remain, corresponding to the correlations of the measured constant time. If the collector resistance of the resistor 8 is much less than the resistance of the resistor 16, and the control unit, the pulse amplitude is set to 0.37 UQ, where Uo is the voltage of the power supply, the time interval counted by the time counter 7 is equal to the RC time constant .

Claims (1)

Apparatus of the Invention A device for measuring the constant time of a parallel RC circuit, comprising a pulse generator, an indication unit and a transistor, the collector of which is connected to the input of the pulse amplitude control unit and through the first resistor to the power supply unit, the emitter is connected via a diode to the KS circuit under study, and the base is connected to the first end of the second resistor, characterized in that, in order to improve accuracy and speed, a switch, mode trigger, stop trigger, delay counter, counter, brute force are entered into it. , the code comparison unit, the switch information input is connected to the output of the pulse generator, the first control switch input is connected to the mode trigger output, the input of the time counter and the reset input of the edge counter, the second control input of the switch is connected to the stop trigger output, the input which is connected to the output of the pulse amplitude control unit, the first output of the switch is connected to the input of the delay counter, the output of which is connected to the first input of the mode trigger, the second input of which is connected to ervym input latch mode, the second input of which is connected to a second resistor and a second vshodom code comparing unit output, the first input of which is connected to the first vkodom time counter. The required accuracy of the measurement is the second output of which is connected with a block of time achieved by selecting the hour-40 clo display, while the second output of the generator 5 is generated. The speed of the device is connected to the input of the counting unit due to the complete connected to the automation of the measurement process. with the second input of the code comparison unit. thirty 35 ten 25 15 25 20 25 thirty 20 25 35