SU496677A1 - Resistance to pulse frequency converter - Google Patents

Description

3

The block diagram of the impedance-to-pulse frequency converter contains a voltage source 1, a divider 2 from the reference and measured resistors, two-position switch 3, force-. DC 4 with switchable gain, Integrator 5, Comparison Device 6, Period selector 7, / Pulse generator 8.

The impedance-to-frequency converter operates as follows. In the initial state (in the absence of a control signal at the output of the selector 7), the inverting input of the integrator 5 is connected via a two-position switch 3 to the ground bus, a non-inverting input of the integrator through a DC amplifier 4, the gain of which (when these conditions) is equal to one, connected to the output of divider 2. The output voltage of the integrator 5 varies linearly with the speed x (where

E is the nominal value of the output voltage of voltage source 1; R is the resistance of the reference resistor; F - soX

the resistance of the measured resistor, and t is the constant of the integrator time 5 and

the expiration of time interval i, the output

one

the integrator voltage reaches a certain threshold level (and.). In this case, the comparison device triggers, and at the output of the selector 7, with the arrival of the next pulse from the generator 8, a control pulse of duration t is formed, equal to

For the duration of the specified control pulse, the inverting input of the integrator 5 is connected via a two-position switch 3; to the output of the voltage source 1, and the gain of the amplifier 4 changes (in general, its gain becomes K) . At the same time, the -: sign of the derivative of the linear-measurer is changed. state voltage at the output of the integrator 5 .; After the time interval t;

the inverting input of the integrator 5 again

connects to the ground bus, and in amplifier 4 the gain becomes equal to one again. In the following processes in the circuit repeat v-I,

The steady state operation of the converter is characterized by the equation:

 -out

R (2-K) -t

The considered converter when has a linear characteristic of the transformation, and the stability of the slope-h

I conversion is not determined by the stability of the voltage supplying the measuring

 a circuit (a divider from the model and the measured resistors). In addition, in this converter, due to a change in the gain factor K, it is possible to change the nature of the conversion function over a wide range, which is especially important for linearizing the conversion characteristic in the case of working with resistive sensors.

Subject invention

A impedance-to-pulse frequency converter containing an integrator, the output of which is connected to the output of the period selector through a comparator, to the signal input of which a pulse generator is connected, and to the output - control input of a two-position switch, one input of which is connected to the source and the dividers from the model and measured resistors, the other input is from the common circuit, and the output is the inverting input of the integrator, which also allows you to increase the accuracy and p enhancement of functionality, a DC amplifier with a switching coefficient is introduced into it ({1-gain amplifier, the signal input of which is connected to the output of the divider from the reference and measured resistors, the control input - to the output of the period selector and the entire course - to the i-wiring input integrator. J