High-precision timing circuit

Abstract

A high-precision timing circuit comprises a sinusoidal signal generating circuit, a primary amplifying circuit, a tuning amplifying circuit and an amplitude limiting amplifying circuit. The digital transformation of the timing circuit is realized, and the reliability of equipment is improved; the system is higher in working stability, more convenient to check and debug and less affected by environmental factors; the method for guaranteeing the equipment technology is broadened, the problem of spare part shortage is solved, and the application efficiency of the equipment is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of timing circuits, and mainly relates to a high-precision timing circuit. Background Art

[0002] As the timing center of the equipment, the timing circuit is the fundamental guarantee for the coordinated work of various systems and the basic requirement for the stable operation of the equipment.

[0003] The timing circuit of existing equipment mainly adopts electron tube crystal oscillator and is built with analog components. The circuit inspection and debugging are difficult, which is not conducive to fault detection. With the increase of service life, the components of the timing circuit have far exceeded their service life. The stability of the oscillator is poor, which affects the accuracy of the timing pulse. At this time, the signal accuracy can no longer meet the timing requirements of the equipment, and the failure rate is high. Once a failure occurs, there are no corresponding spare parts on the market to replace it. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention provides a high-precision timing circuit.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A high-precision timing circuit comprises a sinusoidal signal generating circuit, a primary amplifier circuit, a tuning amplifier circuit and a limiting amplifier circuit;

[0007] The sinusoidal signal generating circuit is used to generate a 75KHz sinusoidal signal. The 75KHz sinusoidal signal generated by the sinusoidal signal generating circuit is passed through a primary amplifier circuit and a tuning amplifier circuit to generate two 75KHz sinusoidal signals with equal amplitudes and opposite phases. The other 75KHz sinusoidal signal output from the tuning amplifier circuit is output as a 75KHz square wave signal after passing through a limiting amplifier circuit.

[0008] The sinusoidal signal generating circuit comprises a single chip microcomputer, a DDS device, an active crystal oscillator, a low-pass filter, a broadband amplifier and a voltage-stabilized power supply; the single chip microcomputer transmits a data signal and a control signal to the DDS device, and the output signal of the DDS device is sequentially passed through a low-pass filter and a broadband amplifier to output a sinusoidal signal; the active crystal oscillator provides a fixed frequency for the DDS device, and the voltage-stabilized power supply supplies power for the single chip microcomputer, the DDS device, the active crystal oscillator, the low-pass filter and the broadband amplifier.

[0009] The active crystal oscillator is 125MHz; the model of the single-chip microcomputer is AT89S52; the model of the DDS device is AD9850; the low-pass filter is used to filter out stray and harmonic signals; the broadband amplifier is used for power amplification; the voltage-stabilized power supply provides two power supplies, 5V and 6V, wherein the 5V power supply is used to power the AT89S52, AD9850, and 125MHz active crystal oscillator, and the 6V power supply is used to power the low-pass filter and the broadband amplifier; the sinusoidal signal generating circuit outputs a sinusoidal signal with an amplitude of 5V and a frequency of 75KHz.

[0010] The primary amplifying circuit comprises: a first triode, a bias circuit, a first transformer, a 12V power supply, a first filtering circuit, a 24V power supply, a second filtering circuit, a primary amplifying circuit output port and a waveform detection port;

[0011] The 12V power supply is electrically connected to the bias circuit and one end of the primary coil of the first transformer after being filtered by the first filter circuit. The other end of the primary coil of the first transformer is electrically connected to the collector of the first transistor. The bias circuit provides a stable static operating point for the first transistor, so that it works in a stable amplification region.

[0012] The collector of the first triode is connected in series with the first resistor and then electrically connected to the waveform detection port;

[0013] The 24V power supply is filtered by the second filtering circuit and electrically connected to one end of the secondary coil of the first transformer after being connected in series with the sixth resistor, and the other end of the secondary coil of the first transformer is electrically connected to the output port of the primary amplifier circuit;

[0014] The sinusoidal signal generated by the sinusoidal signal generating circuit is coupled to the base of the first transistor through the fifth capacitor, amplified by the first transistor, and then output to the output port of the primary amplifier circuit through the secondary coil of the first transformer.

[0015] The tuning amplifier circuit comprises: a second triode, a second transformer, a third transformer, a 24V power supply and a third filtering circuit;

[0016] The primary coils of the second transformer and the third transformer form a tuning circuit with multiple capacitors; the 24V power supply is electrically connected to one end of the tuning circuit via the third filtering circuit, and the other end of the tuning circuit is electrically connected to the collector of the second triode. The base of the second triode receives the output signal of the primary amplifier circuit, and the emitter of the second triode is connected in series with an adjustable resistor and a ninth resistor in sequence and then grounded; the secondary coil of the second transformer outputs two sinusoidal signals with equal amplitude and opposite phases, and the secondary coil of the third transformer is electrically connected to the limiting amplifier circuit.

[0017] The limiting amplifier circuit includes: a third triode, the base of the third triode is electrically connected to one end of the secondary coil of the third transformer, the emitter of the third triode is connected in series with an eleventh resistor and then grounded, the twelfth capacitor is connected in parallel to the eleventh resistor, the collector of the third triode is connected in series with a tenth resistor and then connected to a 12V power supply, the 12V power supply is connected in series with the twelfth resistor and then electrically connected to the other end of the secondary coil of the third transformer and one end of the thirteenth resistor, and the other end of the thirteenth resistor is grounded; the collector of the third triode is connected to the output port.

[0018] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages:

[0019] The present invention provides a high-precision timing circuit, which realizes the digital transformation of the timing circuit and improves the reliability of the equipment; the system has higher working stability, is more convenient for inspection and debugging, and is less affected by environmental factors; it broadens the method of technical guarantee for equipment, solves the problem of shortage of spare parts, and further improves the application efficiency of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the principle diagram of the timing circuit of the utility model;

[0021] Figure 2 It is a principle block diagram of the utility model;

[0022] Figure 3 It is the schematic diagram of the sinusoidal signal generating circuit;

[0023] Figure 4 It is the principle block diagram of the amplifier circuit;

[0024] Figure 5 It is the circuit diagram of the primary amplifier circuit;

[0025] Figure 6 It is the circuit diagram of the tuning amplifier and limiting circuit. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Apply this design to the time center of a certain device, such as Figure 1As shown in or 2, a 75KHz sine signal with an amplitude of 5V is generated by a sine signal generating circuit, and then amplified by an amplifier circuit to generate two 75KHz sine signals with an amplitude ≥18V and one 75KHz square wave signal with an amplitude ≥15V.

[0028] The overall circuit design is divided into two parts. The first part is the sinusoidal signal generation circuit, which consists of a single-chip microcomputer, a DDS device and its peripheral circuits, and is used to generate a highly stable 75KHz 5V sine wave.

[0029] Specifically, Figure 3 As shown, the sinusoidal signal generating circuit includes a single-chip microcomputer, a DDS device, an active crystal oscillator, a low-pass filter, a broadband amplifier and a voltage-stabilized power supply; the single-chip microcomputer transmits the data signal and the control signal to the DDS device, and the output signal of the DDS device is sequentially passed through the low-pass filter and the broadband amplifier to output a sinusoidal signal; the active crystal oscillator provides a fixed frequency for the DDS device, and the voltage-stabilized power supply supplies power for the single-chip microcomputer, the DDS device, the active crystal oscillator, the low-pass filter and the broadband amplifier.

[0030] Among them, the active crystal oscillator is 125MHz; the model of the single-chip microcomputer is AT89S52; the model of the DDS device is AD9850; the low-pass filter is used to filter out stray and harmonic signals; the broadband amplifier is used for power amplification; the regulated power supply provides two power supplies, 5V and 6V, among which the 5V power supply is used to power the AT89S52, AD9850, and 125MHz active crystal oscillator, and the 6V power supply is used to power the low-pass filter and the broadband amplifier; the circuit outputs a sinusoidal signal with an amplitude of 5V and a frequency of 75KHz.

[0031] The second part is the amplifier circuit, such as Figure 4 As shown, the amplifier circuit is divided into: primary amplifier circuit, tuning amplifier circuit and limiting amplifier circuit. The high-stability signal with an amplitude of 5V and a frequency of 75KHz generated by the sinusoidal signal generating circuit generates two 75KHz sinusoidal signals with equal amplitude and opposite phases through the primary amplifier circuit, tuning amplifier circuit and limiting amplifier circuit, which are used by the ranging system of a certain device; at the same time, a 75KHz square wave signal is generated to provide a timing signal for the transmitting system and display system of a certain device.

[0032] Specifically, Figure 5 As shown, the primary amplifier circuit includes: a first transistor BG1, a bias circuit, a first transformer B1, a 12V power supply, a first filter circuit, a 24V power supply, a second filter circuit, a primary amplifier circuit output port and a waveform detection port CK1;

[0033] The 12V power supply is electrically connected to the bias circuit and the end 1 of the primary coil of the first transformer B1 after being filtered by the first filter circuit. The other end 2 of the primary coil of the first transformer is electrically connected to the collector of the first transistor BG1. The bias circuit provides a stable static operating point for the first transistor BG1, so that it works in a stable amplification region.

[0034] The collector of the first transistor BG1 is connected in series with the first resistor R1 and then electrically connected to the waveform detection port CK1;

[0035] The 24V power supply is filtered by the second filter circuit, and is connected in series with the end 4 of the secondary coil of the first transformer B1 after passing through the sixth resistor R6. The other end 3 of the secondary coil of the first transformer is electrically connected to the output port of the primary amplifier circuit.

[0036] The sinusoidal signal generated by the sinusoidal signal generating circuit is coupled to the base of the first transistor BG1 through the fifth capacitor C5, and after being amplified by the first transistor BG1, it is output to the output port of the primary amplifier circuit through the secondary coil of the first transformer B1, and the output signal amplitude is 10V. The waveform detection port CK1 is used to detect the collector waveform of the first transistor BG1. The normal test waveform frequency is 75KHz and the amplitude is 10~12V.

[0037] like Figure 5 As shown, the second resistor R2, the third resistor R3, and the fifth resistor R5 constitute a bias circuit of the first transistor BG1, the seventh capacitor C7 is a filter capacitor for ensuring the stability of the amplifier circuit, the fifth capacitor C5 is a coupling capacitor at the input end, the first inductor L1, the first capacitor C1, the third capacitor C3, and the fourth resistor R4 are a +12V first filter circuit, the second inductor L2, the second capacitor C2, and the fourth capacitor C4 are a +24V second filter circuit, and the sixth resistor R6 provides a smaller positive bias voltage for the next-stage tuned amplifier circuit to reduce the excitation voltage and increase the output power.

[0038] Specifically, Figure 6 As shown, the tuning amplifier circuit includes: a second transistor BG2, a second transformer B2, a third transformer B3, a 24V power supply and a second filter circuit;

[0039] The primary coils of the second transformer B2 and the third transformer B3 form a tuning circuit with multiple capacitors; the 24V power supply is filtered by the second filtering circuit, and is electrically connected to one end of the tuning circuit after being connected in series with the seventh resistor R7, and the other end of the tuning circuit is electrically connected to the collector of the second triode BG2, the base of the second triode BG2 receives the output signal of the primary amplifier circuit, and the emitter of the second triode BG2 is connected in series with the adjustable resistor W1 and the ninth resistor R9 in sequence and then grounded; the secondary coil of the second transformer B2 outputs two sinusoidal signals with equal amplitude and opposite phases, and the secondary coil of the third transformer B3 is electrically connected to the following limiting amplifier circuit.

[0040] The 10V and 75KHz sinusoidal signal from the primary amplifier circuit is sent to the base of the second transistor BG2, and then the secondary coil of the second transformer B2 outputs two 75KHz sinusoidal signals with equal amplitude and opposite phase for use by the ranging system. The output signal amplitude is ≥18V.

[0041] The limiting amplifier circuit includes: a third triode BG3, the base of the third triode BG3 is electrically connected to one end 3 of the secondary coil of the third transformer B3, the emitter of the third triode BG3 is connected in series with the eleventh resistor R11 and then grounded, the twelfth capacitor C12 is connected in parallel to the eleventh resistor R11, the collector of the third triode BG3 is connected in series with the tenth resistor R10 and then connected to the 12V power supply, the 12V power supply is connected in series with the twelfth resistor R12 and then electrically connected to the other end 4 of the secondary coil of the third transformer B3 and one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is grounded; the collector of the third triode BG3 is connected to the output port.

[0042] A 75KHz sinusoidal signal is output from the secondary coil of the second transformer B3 and sent to the base of the third transistor BG3. The lower part of the sinusoidal wave is cut off by the inter-electrode equivalent diode between the base and the emitter, and the upper part is cut off by the collector saturation limiter to form a 75KHz square wave, which provides a timing signal for the transmitting system and the display system, and its amplitude is ≥15V. CK2 is used to detect the collector waveform of the second diode BG2. The normal test waveform is 75KHz frequency and 20V amplitude.

[0043] The second transistor BG2 plays the role of isolation and amplification, the ninth resistor R9 is a negative feedback resistor, the adjustable resistor W1 is an emitter resistor, and the output waveform amplitude can be changed by adjusting the adjustable resistor W1. The eighth capacitor C8, the ninth capacitor C9, the tenth capacitor C10, and the eleventh capacitor C11 form a tuning loop with the primary coils of the second transformer B2 and the third transformer B3. The twelfth resistor R12 and the thirteenth resistor R13 provide a small positive bias voltage for the third transistor BG3. The tenth resistor R10 and the eleventh resistor R11 are respectively the collector and emitter resistors of the third transistor BG3. The twelfth capacitor C12 is a filter capacitor, and the second inductor L2, the second capacitor C2, and the fourth capacitor C4 are a +24V filter circuit. The secondary coil of the second transformer B2 outputs two 75KHz sinusoidal signals with equal amplitude and opposite phases, and the collector of the third transistor BG3 outputs a 75KHz square wave signal.

[0044] The parts not described in detail in the above content are prior art, so they are not described in detail.

Claims

1. A high-precision timing circuit, characterized in that: It includes a sinusoidal signal generating circuit, a primary amplifier circuit, a tuning amplifier circuit and a limiting amplifier circuit; The sinusoidal signal generating circuit is used to generate a 75KHz sinusoidal signal. The 75KHz sinusoidal signal generated by the sinusoidal signal generating circuit is passed through a primary amplifier circuit and a tuning amplifier circuit to generate two 75KHz sinusoidal signals with equal amplitudes and opposite phases. The other 75KHz sinusoidal signal output from the tuning amplifier circuit is output as a 75KHz square wave signal after passing through a limiting amplifier circuit.

2. The high-precision timing circuit according to claim 1, characterized in that: The sinusoidal signal generating circuit includes a single-chip microcomputer, a DDS device, an active crystal oscillator, a low-pass filter, a broadband amplifier and a voltage-stabilized power supply; the single-chip microcomputer transmits data signals and control signals to the DDS device, and the output signal of the DDS device is sequentially passed through a low-pass filter and a broadband amplifier to output a sinusoidal signal; the active crystal oscillator provides a fixed frequency for the DDS device, and the voltage-stabilized power supply supplies power for the single-chip microcomputer, the DDS device, the active crystal oscillator, the low-pass filter and the broadband amplifier, and the sinusoidal signal amplitude output by the sinusoidal signal generating circuit is 5V.

3. The high-precision timing circuit according to claim 2, characterized in that: The active crystal oscillator is 125MHz; the model of the single-chip microcomputer is AT89S52; the model of the DDS device is AD9850; the low-pass filter is used to filter out stray and harmonic signals; the broadband amplifier is used for power amplification; the voltage-regulated power supply provides two power supplies, 5V and 6V, of which the 5V power supply is used to power the AT89S52, AD9850, and 125MHz active crystal oscillator, and the 6V power supply is used to power the low-pass filter and the broadband amplifier.

4. The high-precision timing circuit according to claim 2, characterized in that: The primary amplifying circuit comprises: a first triode, a bias circuit, a first transformer, a 12V power supply, a first filtering circuit, a 24V power supply, a second filtering circuit, a primary amplifying circuit output port and a waveform detection port; The 12V power supply is electrically connected to the bias circuit and one end of the primary coil of the first transformer after being filtered by the first filter circuit. The other end of the primary coil of the first transformer is electrically connected to the collector of the first transistor. The bias circuit provides a stable static operating point for the first transistor, so that it works in a stable amplification region. The collector of the first triode is connected in series with the first resistor and then electrically connected to the waveform detection port; The 24V power supply is filtered by the second filtering circuit and electrically connected to one end of the secondary coil of the first transformer after being connected in series with the sixth resistor, and the other end of the secondary coil of the first transformer is electrically connected to the output port of the primary amplifier circuit; The sinusoidal signal generated by the sinusoidal signal generating circuit is coupled to the base of the first transistor through the fifth capacitor, amplified by the first transistor, and then output to the output port of the primary amplifier circuit through the secondary coil of the first transformer.

5. The high-precision timing circuit according to claim 2, characterized in that: The tuning amplifier circuit comprises: a second triode, a second transformer, a third transformer, a 24V power supply and a second filtering circuit; The primary coils of the second transformer and the third transformer form a tuning circuit with multiple capacitors; the 24V power supply is filtered by the second filtering circuit, and is electrically connected to one end of the tuning circuit after being connected in series with the seventh resistor, and the other end of the tuning circuit is electrically connected to the collector of the second triode, the base of the second triode receives the output signal of the primary amplifier circuit, and the emitter of the second triode is connected in series with an adjustable resistor and a ninth resistor in sequence and then grounded; the secondary coil of the second transformer outputs two sinusoidal signals with equal amplitude and opposite phases, and the secondary coil of the third transformer is electrically connected to the limiting amplifier circuit.

6. The high-precision timing circuit according to claim 5, characterized in that: The limiting amplifier circuit includes: a third triode, the base of the third triode is electrically connected to one end of the secondary coil of the third transformer, the emitter of the third triode is connected in series with an eleventh resistor and then grounded, the twelfth capacitor is connected in parallel to the eleventh resistor, the collector of the third triode is connected in series with a tenth resistor and then connected to a 12V power supply, the 12V power supply is connected in series with the twelfth resistor and then electrically connected to the other end of the secondary coil of the third transformer and one end of the thirteenth resistor, and the other end of the thirteenth resistor is grounded; the collector of the third triode is connected to the output port.

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