RU21320U1 - VOLTAGE CONVERTER FREQUENCY - Google Patents

Abstract

A voltage to frequency converter containing a Schmitt trigger, the input of which through a capacitor is connected to a common bus and to one end of a constant resistor, characterized in that, in order to expand the functionality, two variable resistors and a multiplexer are introduced into it, the first output of which is through the first variable the resistor is connected to an external voltage source, and the second output through a second alternating resistor is connected to a common bus, while the address input of the multiplexer is connected to the output of the Schmitt trigger, and inform insulating input is connected to the second end of the fixed resistor.

Description

A utility model of a voltage to frequency converter relates to the field of pulsed technology and can be used in digital measuring devices.

Known pulse generator with electronic frequency tuning, containing an operational amplifier, a capacitor, two field-effect transistors and three resistors, described in A.S. USSR No. 786012, M.Kji. H 03 L 1/00, 12/07/80. However, this generator is powered by a bipolar power source, which means that the output pulses are also bipolar. In this generator, at high frequencies, the steepness of the fronts decreases, which makes it difficult to use it in high-speed digital devices.

A known pulse generator containing a Schmitt trigger, a capacitor and a resistor described in Dimitrova M.I., Punzhev V.P. 33 Schemes on the triggers: TRANS. with bulg. - L .: Energoatomizdat. Leningrad Department, 1990. - p. 80. However, this generator operates at a fixed frequency, which significantly narrows the scope of its application.

The task at hand is the expansion of functionality.

For this, a pulse generator containing a Schmitt trigger, the input of which through a capacitor is connected to a common busbar and to one end of a DC resistor, additionally contains two variable resistors and a multiplexer, the first output of which is connected to an external voltage source through the first variable resistor and the second output through the second

a variable resistor - with a common bus, while the address input of the multiplexer is connected to the output of the Schmitge trigger, and the information input is connected to the second end of the constant resistor.

In FIG. 1 shows a functional diagram of a voltage-to-frequency converter.

The voltage to frequency converter contains a Schmitt trigger 1, a capacitor 2, a constant resistor 3, a multiplexer 4, two variable resistors 5 and 6, an input terminal 7 and an output terminal 8. The input of the Schmitt trigger 1 through a capacitor 2 is connected to the common bus, and through a constant resistor The 3rd information input of the multiplexer 4, the address input of which is connected to the output terminal 8, the first output of the multiplexer 4 through the variable resistor 5 is connected to the input terminal 7, and the second output of the multiplexer 4 through the variable resistor 6 is connected to the common bus. Schmitt trigger 1 and multiplexer 4 are connected to a power source and a common bus.

In FIG. 2 shows timing diagrams explaining the principle of operation of the converter.

The voltage-to-frequency converter operates as follows.

When the converter power is turned on, the output of the Schmitt trigger 1 is set to a high voltage Uvx, while the multiplexer 4 is connected to an external voltage source via terminal 7. The capacitor 2 is charged exponentially from the control voltage source

the law with the time constant TI determined by resistors 3 and 5, and at the time when the voltage at the input of the Schmitt trigger reaches the upper switching threshold UB, it switches to the state with a low output voltage UBHX. In this case, the multiplexer 4 switches to the common bus and the capacitor 2 discharges with a time constant TI determined by resistors 3 and 6. When the voltage at the input of the Schmitt trigger reaches the lower threshold UH, it switches to the state with a high level of output voltage and the process repeats. The pulse repetition period is determined by the formula as T Ti + T2, and:

where TI and T2 are the periods of charge and discharge of the capacitor 2, respectively;

R is the resistance of the constant resistor 3;

RI is the resistance of the variable resistor 5;

R 2 is the resistance of the variable resistor 6;

C is the capacitance of the capacitor 2;

UbHem - voltage of an external source;

UH - lower trigger level of the Schmitt trigger;

UB - the upper level of the Schmitt trigger.

The pulse repetition rate is determined by the ratio:

T, (

and, „, - and,

T, (R + P,). C-ln

Thus, with the help of variable resistors 5 and 6, the duty cycle of the pulses is adjusted at the output of the generator, and the range of changes in the frequency of the pulses is also regulated.

Applicant Orel State Technical University (Oryol State Technical University)

Vice-rector for scientific work

and international -

. „. t

Professor, Doctor of Technical Sciences . , - {/ MJ - Stepanov Yu.S.

Claims (1)

A voltage to frequency converter containing a Schmitt trigger, the input of which through a capacitor is connected to a common bus and to one end of a constant resistor, characterized in that, in order to expand the functionality, two variable resistors and a multiplexer are introduced into it, the first output of which is through the first variable the resistor is connected to an external voltage source, and the second output through the second variable resistor is connected to a common bus, while the address input of the multiplexer is connected to the output of the Schmitt trigger, and inform insulating input is connected to the second end of the fixed resistor.