SU204019A1 - THE CONVERTER OF THE RELATION OF TWO VOLTAGES OF THE DC VOLTAGE INTO A SIGNAL WITH LATITUDENT PULSE MODULATION - Google Patents

Description

Devices are known for converting the ratio of two DC voltages into a pulse-width modulated signal, comprising a null organ, a single vibrator, an amplitude limiter with an RC drive in a feedback circuit.

The proposed device differs from the known ones in that it contains a one-shot connected to a bullet-organ, one input of which is connected to the output of the first transformed voltage, and the other input to the output of an RC-chain connected through an amplitude limiter to the output of the one-shot.

This simplifies the circuit and provides a linear conversion function for the ratio of two DC voltages to a value directly proportional to the pulse duty cycle with a variable repetition rate.

The device performs the operation - -

at,

where Ui is the first voltage to be converted;

Uz is the second voltage to be converted;

t is the pulse duration at the output

roystva; in fig. 2 - its basic scheme.

The converter contains a null organ L on one of the inputs of which voltage 6b is supplied to one-oscillator 2 with a short recovery time, the output stage of which operates in two-stroke key mode, and feedback circuit 3 consisting of a pulse amplitude limiter and an RC accumulator. A second voltage 1/2 is applied to the input of the limiter, and the output of the RC accumulator is connected to the second input of the null organ 1.

The zero-body 1 is made according to a typical blocking-generator circuit at a high-frequency transistor. In order to improve the stability of the device at low voltages t / i, a chain 4 is inserted, which forms a positive pulse from a one-shot pulse and locks the null organ after starting

one-shot. Stump 4 is connected to the output of the latter through the coupling capacitor 5 and the diodes 6 and 7.

The limiter of the amplitude of the pulses in the feedback circuit is made according to the standard scheme on

two transistors 8 and 9 and is connected to the output of a single vibrator via a ballast resistance 10. The voltage of the limitation U is supplied to the collectors of the transistors, and the output of the limiter is connected via an RC chain //, 12

The single-vibration 2 is made of transistors 13, 14, J5 and 16. In order to reduce the recovery time of the one-shot feedback capacitor 17 is connected from the output of the terminal stage to the input of the transistor 13. A triggering pulse from the zero-body to the base of the transistor 14 diode 19.

According to the supply circuits, the zero-organ is separated from the single-vibration by the isolating chain 20, 21, which with resistance 22 acts as a stabilizer of the operating mode of the transistor 23 at a constant current.

At the initial moment of time, the zero-organ 1 and the single-oscillator 2 are in stable states, the voltage at the output of the device is Lo. The limiter in the feedback circuit 3 limits this voltage to U and begins to charge the 12 RC capacitor to the accumulator in the feedback circuit. As soon as the voltage across the capacitor exceeds f / i, the null organ is energized and triggers a one-shot. A triggered one-shot reduces the voltage at the output of the device to zero for the duration of its pulse. During this time, a partial discharge of the capacitor 12 through the resistance // occurs and the voltage at the second input of the zero-body becomes slightly lower than f / i. After returning the one-shot to the initial state, the capacitor 12 starts to charge again through

resistance // to U and, having slightly exceeded it, restarts the zero-body. Then the cycle is repeated. Provided that the RCc time constant is many times longer than the duration of a single-pulse pulse, the average voltage across the capacitor 12 is very close to Vi. If we take the interval between pulses of a single vibrator, the duration of which is equal to t, to the output pulse of the device, then

get -,

where the difference T - t is a constant value and is equal to the duration of a one-shot pulse.

Subject invention

The converter is a ratio of two DC voltages to a signal with a pulse width modulation containing a single vibrator, a null organ and an amplitude limiter with an RC drive in a feedback circuit, characterized in that, in order to simplify the circuit, it contains a single vibrator connected to a zero-organ, one input of which is connected to the source of the first transformable voltage, and the other to the output of the RC-chain connected via an amplitude limiter to the output of a single-oscillator.

Lb

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