SU396813A1 - PULSE GENERATOR - Google Patents

Description

one

The invention relates to devices of pulsed technology and can be used in automation, telemechanics and computer technology as the time of a pulse modulator.

Known impulse generators are known for generating short, rectangular pulses, the time between which is determined by the parameters of the RC chain in the emitter of the matching transistor and the potential of its base, determined by the parameters of the voltage divider. However, the known generators have a fixed time between pulses, and the minimum resistance of the resistors in the emitter and base circuits of the comparison transistor 1 can cause self-oscillations to fail due to the high saturation of the transistors.

The iB of the proposed generator for controlling the oscillation period is proportional to the input voltage and increasing the self-oscillation stability to the base of the comparing transistor. An input source is connected via an additional resistor, and the RC circuit resistor is connected between the comparator emitter and the output transistor collector.

The drawing shows a schematic diagram of a pulse generator. It contains a collector resistor 1 of the output transistor, an RC circuit resistor 2, an RC circuit capacitor 5, a feedback diode 4, a feedback capacitor 5 that compares a transistor of one conductivity type 6, an output transistor of a different conductivity type 7, an auxiliary resistor 8, constant voltage input 9.

The constant time of the chain formed by the feedback capacitor 5 and the additional resistor 8 is chosen to be significantly less than the time constant of the chain formed by the resistor of the RC chain 2 and the capacitor of the RC chain 3. Then when the power is turned on: the capacitor 5 is quickly charged through the resistor 8 and input source 9 to a voltage equal to the difference of the collector voltage of the locked output transistor 7 and the signal source voltage. After that, the potential of the base of the comparison transistor 6 will be equal to the voltage of the input signal 9. The capacitor 3 is relatively slowly charged through the resistor 2 from the collector voltage of the locked output transistor. When the voltage on the capacitor 3 reaches the voltage of the input signal 9, the comparing transistor 6 starts to open, thus opening the transistor 7.

Due to the positive feedback through the capacitor 5, and then the diode 4, the transistors quickly open and go into saturation, while the capacitor 3 is discharged

the emitter current of the transistor 6. After the discharge of the capacitor 3, the emitter current of the transistor 6 decreases to zero, since the current through the resistor 2 is very small due to a small voltage drop on the open output transistor 7 After that both transistors lock the voltage on the collector of the output transistor 7 is restored and starts, again the process of charging capacitors.

Using

The initial voltage on the condensate of the exponent is approximately equal to:

t

and, and

(Ri + R,) Sz

de RI is the resistance of the resistor /; R2 is the resistance of resistor 2; Sz - capacitor capacitance 5; Un - power supply; t - time

At the moment of opening the transistors of the laziness of the output pulse, the voltage of the capacitor is equal to the voltage of the input source, i.e.

. (. +.) Sz.

 P

The last formula shows that the time between pulses is proportional to the input signal.

Subject invention

A pulse generator containing the time specifying the RC chain in the emitter of the matching transistor of one type of conductivity, the output transistor of a different type of conductivity with a load resistor in the collector circuit, a diode and a feedback coherent connected to the output collector and the base of the matching transistors, in order to obtain an interval between pulses proportional to the input control voltage, an input source is connected to the base of the comparing transistor via an additional resistor voltage.

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