SU682845A1 - Digital resistance measuring device - Google Patents

Description

A horo switch, the midpoint of which is connected to the output of the counting key, and the control input is connected to the third output of the control unit, the fourth output of which is connected to the control input of the code converter in the pulse train.

The drawing shows a block diagram of a digital resistance meter.

The circuit contains measurable resistance 1, digital-analog converter 2 resistance, capacitor 3 with a constant known capacitance C, input non-switches 4 and 5, sources of charging 6 and threshold 7 voltages, comparison device 8, pulse generator 9, counting key 10 , a two-way switch 11, a code to pulse sequence converter 12, a differential pulse counter 13, a rewriting matrix 14 and a control unit 15 controlling the operation of input switches 4 and 5, a two-position switch 11, a converter l 12 code in a sequence of pulses and rewriting the matrix 14.

The device works as follows.

According to the measurement start signal from the control unit 15, using the switch 5, the capacitor 3 is connected to the source G of the charging voltage. The capacitor 3, charged up to the voltage U, closes on the measured resistance 1, the key 10 opens simultaneously and through the two-position switch And the difference counter 13 starts to receive the generator pulses through the direct counting board. The comparator starts to operate when the discharge voltages are equal and source 7 threshold voltage Un U / l. At the time of comparison, the device 8 closes the key 10, blocking the access of pulses to the counter 13.

The obtained digital equivalent from the counter 13 is inputted into the rewriting matrix 14 and into the memory block of the converter 12. With the help of a digital-to-analog converter, this digital equivalent is converted into resistance. Switch 11 is switched to the position that closes its input to the subtraction counter of meter 13, and switch 4 connects the output of converter 2 to the input of device 8. In the same way as described, a digital resistance measurement is performed, the result of which is fed to counter 13 via the subtraction bus. At the same time, at the moment of the beginning of measurement of the resistance, the signal from block 15 starts converting the digital equivalent of the input resistance 1 stored in the memory of the converter 12 into a pulse sequence. pulses resulting from conversion to an impedance code. The operation of the difference counter 13 is constructed so that it enters a particular state only at the end of the incoming pulses.

The resulting difference in the counter 13 is simultaneously summed with the digital equivalent of the input impedance 1, obtained and recorded in the counter after the first elementary measurement cycle. Thus, by the end of the second elementary measurement cycle, a first adjustment is obtained in the difference meter.

the result, which is converted by a converter 2 into a resistance. The latter is converted into a digital equivalent, which in counter 13 is simultaneously subtracted from the input code

the resistance 1 reproduced in the pulse train by the transducer 12, and the resulting difference is added to the first corrected digital equivalent, forming the second corrected result.

In this and subsequent cycles, the state of all keys, with the exception of switch 5, remains unchanged and then the correction can be continued in the same way as a specified number of times.

Formula and 3 optics

A digital resistance meter containing a capacitor, a digital-to-analog resistance converter, a comparison unit, one input of which is connected to the midpoint of the first and one terminal of the second input switches, the source of the charging voltage, the output of which is connected to the second terminal of the second switch, the source voltage of the threshold voltage connected to another input of the comparison device, pulse generator, key

account, connected to the outputs of the comparator and the generator, rewriting matrix, the output of which is connected to the input of the digital-analog converter of the resistance connected to the terminal of the first switch, the other terminal of which is connected to the input of the meter, and the control unit, two outputs of which are connected to the control switch inputs and rewriting matrix, which is also distinguished by the fact that, in order to increase speed, it is equipped with a code converter in a sequence of pulses, a two-position switch and a differential pulse counter, the outputs of which

connected to the inputs of the rewriting matrix and the converter of the code into the pulse sequence, the other input of which is connected to the generator output, moreover, the input of the difference counter is connected

to the output of the code converter in a pulse sequence and one terminal of a two-position switch, the subtraction input is connected to the second terminal of the two-position switch, the midpoint of which is connected to the output of the counting key, and the control input is connected to the third output of the control unit, the fourth output of which is connected to the control

input psorazovatsl code in the sequence of pulses.

Sources of information taken into account in the examination

1. USSR author's certificate N «360624, cl. G 01R 27/00, 1972.

2. USSR Author's Certificate No. 500506 G 01R 27/00, 1976.