SU429520A1 - FORMING THRESHOLD DEVICE - Google Patents

Description

one

The invention relates to the field of radio engineering and can be used in the formation of a U-shaped pulse voltage from a smooth input voltage, for example, for an inductive sensor.

Forming devices are known that have been implemented using nopoiroiBbix circuits, for example the Schmidt trigger.

However, the criticality of the output voltage to the parameters of the input voltage and to the temperature of the surrounding medium can lead to a change in the duty cycle of the U-shaped voltage.

In the proposed device for connecting the 1 EFFECT of the input voltage to the operation of the threshold device and maintaining the duty cycle of the output pulses, the output of the amplifier is connected to the circuit for determining the duty cycle of the pulse voltage, the outputs of which are connected to the control inputs of two modulators, the second inputs of which are connected to a sinusoidal voltage generator, and the modulator outputs are connected via a rectifier to the detector input.

FIG. 1 shows a diagram of the proposed device; in fig. 2-time diagrams for the operation of the device.

The device contains a detector 1, and the input of which receives the voltage from the sensor,

Schmidt trigger 2 and amplifier 3, a circuit determining the duty cycle of the pulse voltage at the output of the shaping device 4, assembled on four transistors. Transistor 5 is an emitter follower, transistor 6 is an inverter, and transistors 7 and 8 are turned on so that at the time of formation of the pulse, transistor 7 is closed and open at transistor 8, and at the time of pauses - vice versa. Modulators 9 and 10 are assembled on transistors M and 12, as well as transformers 13 and 14, the secondary windings of which are loaded respectively on rectifiers 15 and 16, consisting of diodes 17, 18 and capacitors 19, 20. On the bases of transistors 11 and 12 is supplied with alternating filling voltage from a 2: 1 generator.

The device works as follows. When the device is working normally, the duration of the pulses and pauses of the generated pulse voltage are equal to each other, i.e. its duty cycle is two. Pr, and this time. During which the transistor 7 is open, is equal to the time during which transistor 8 is open (see fig., 2, a). When from, k | ryt transistor 7, it shunts the collector of transistor 11, including this stage. In the same way, the transistor 8 turns off the cascade on the transistor 12. With a duty cycle, the cascades on the transistors 11 and Ii2 over the period will be

work the same time, and the output voltage of each rectifier 15 and 16 will be equal to each other. Then the average control voltage t / AB over the period will be zero.

When the duty cycle of the generated pulse voltage at the output of the de-forming threshold device is different from two, the average control voltage will have the polarity of this higher temperature, the corresponding cascade of which is less than the Brah during the period, and the greater the duty cycle differs from two the greater the magnitude of this voltage.

Consider the case when the amplitude of the smooth voltage at the input of the forming (Threshold device decreases. This will prolong the pause of the voltage generated by the impulse and the transistor 7 during the period will open longer than the transistor 8. As a result, the cascade on T | The iodine will operate for a longer time than the cascade on the transistor 11. Then the voltage / dB at the output of the rectifier 15 will prevail, and the average control voltage will be negative. and forming the input threshold

devices. consistently with smooth voltage, obtained after detection, and compensates for its reduction. As the amplitude increases, the smooth voltage at the input of the forming threshold device control voltage will be positive and will compensate for this increase.

Similar phenomena occur when the thresholds of a forming threshold device change.

Subject matter

A forming threshold device comprising a detector, a Schmidt trigger and an amplifier, characterized in that, in order to eliminate the influence of the input voltage on the operation of the threshold device and to maintain

the duty cycle of the output pulses, the output of the amplifier is connected to a circuit for determining the duty cycle of a pulse voltage, the outputs of which are connected to the control inputs of two modulators, the second inputs of which are connected to a sinusoidal voltage generator, and the outputs of the modulator are connected via a rectifier to the input of the detector .

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