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Simple Function Generator with Counter Design

Print View , by: iSee ,Total views: 18 ,Word Count: 2242 ,Date: Mon, 22 Jun 2009 Time: 11:19 AM

1 Introduction

Factory measurement of departments, research institutes, university physics laboratory use function signal generator and counter measures, maintenance, laboratory and teaching, but in most cases is to function as a signal generator and counter the two instruments, in order to facilitate research and teaching, together II First, the function signal generator is designed with a counter apparatus.

2 Instrument design

Figure 1 is a function of signal generator and the counter circuit diagram of apparatus, it is by the ICL8038 function generator, square-wave output interface, output interface triangular wave, sine wave output interface, 1 second gate monostable circuit switch, 1 Hz oscillations , and the decimal counter, differential, and a single steady-state control of the audio circuitry, audio oscillator, power circuit components.

Simple Function Generator with Counter Design

2.1 1 Hz oscillator

E1 oscillator by NE555, VR1, R1, R2, C1, C2, composed of self-excited Multivibrator in the power of instant access, C2 capacitor voltage is not mutation, E1 in the 2-pin low-level, so that E1 of the 3-pin and 7-pin voltage is high, 3-pin high voltage through R1 and VR1 power points on the C2-yun, when E1 points to the usual 6-pin power reset, reset the oscillator, so that 7-pin and 3-pin voltage is low, when the voltage on the capacitor C2 through the VR1 and R1 3-pin discharge, discharge voltage when the C2 pin 2 when the threshold voltage, E1 primer flip so that 7 feet and 3-pin into a high, so that a complete oscillation. The oscillator output pulse through the switch K1 band 1 file to the counting circuit counting, light-emitting diode D1 and R3 oscillation signal output for instructions.

2.2 decimal decimal counter code counter circuit can be preset by the number of BCD, reversible counter, BCD decoder driver and team respectively lock LED digital tubes display paragraph 5 decimal counter, as shown in Figure 2. BCD code can be preset number of counts reversible, the CD4510 and CD4511 IC, CD4510B the 6,11,14,2 pin code as a BCD (8421 yards) output to the CD4511B pin 7,1,2,6; count Mountain 15-pin pulses E1 and K1 through a file input, CD4510B 10 pin then add, subtract selector switch K4, high count for the addition, subtraction count is low, 5 is the binary input pin 7 is a binary output pin, when the low of 10 to the counter input of a high pulse signal into the median. CD4510B access the preset number 1 pin selector switch K3, when it is high, you can use BCD code input through the first pin 3,4,12,13 preset number, K3 buy low after the 15-pin CLK the number of input pulse, keep a few on the plus or minus preset.

Seven-Segment locked CD4511B decoding of the BCD and 7,1,2,6 drive output pin CD4510B receive BCD code, by the seventh circuit to show the code, and Seven-Segment LED Driver LED FR105, records show decimal Numerical. Set up a preset number, the number of 1 ~ 99 999, and then keep the number of the basis of this countdown. If no preset number of reset switch can be cleared, counting down from 99,999. AN2 is a reset switch. High when the reset pin CD4510B 9. Counter the use of the 5V power supply, the VSS client to connect with the public. The counter has three input signal terminal, the first input signal through the switches K1-band access to a profile of the pulse signal E1; the second switching signal K1 of the 2-band file, receiving the pulse signal from the ICL8038; third K1-band input signal switch through 3 file access to external pulse signal.

2.3 Differential circuit

Counter to start counting from 0, when the count to 100, CD4510B 11-pin and 2 pin output high, the two high level signals back to the 74LS38 NAND Gate 1 input pin and 2 pin, output low level, C3 and R6 differential circuit components, as the C3 capacitor voltage does not change, a positive differential signal E2 of the 2-pin monostable trigger does not work, change the negative input to the differential signal E2 monostable trigger the 2-pin so that E2 high output 3-pin to 6-pin to control the CD4066 to CD4066 8-pin and 9 pin open and shorted.

2.4 audio monostable control circuit

E2 is a by IC NE555, C4, C5, C6, C7, VR7, R5, D2 component monostable delay circuit, connected to the power of the moment, as the voltage on the capacitor C4 is not mutation, E2 4-pin forced reduction in the state, E2 3-pin output 0 V, while the 7-pin E2 of the transistor in the internal current state of irrigation, so no voltage C6, waiting for 2-pin differential signal to the negative trigger, when the negative input changes differential signal to trigger monostable E2 at 2-pin, C4 to high voltage points, to prepare for the trigger, when E2 and the 3-pin 7-pin is high, 7-pin internal transistor in open-circuit. Supply voltage VR2 through R7 and points to the C6, when the points reset voltage E2 voltage, E2 reversed for the reset state, that is, 3-pin and 7 pin at low level, C6 transient voltage discharge pin 7 to achieve monostable delay circuit function, the output of a pulse, and wait for a differential signal F trigger. Pulse width by the time constant of the C6 (R7 + VR2) decision.

2.5 audio oscillator

E3 circuits by NE555, C7, C8, R10, R11, VR3 Multivibrator audio components. Instant access to power, C8 capacitor voltage is not mutation, E3 is in the 2-pin low-level, so that the E3-pin 3-pin and 7 are in a high voltage, 3-pin high voltage through R10 and VR3 charging points on the C8, E3, when the 6 points to the reset pin power in peacetime, oscillator reset to 7-pin and 3-pin voltage is low, when the voltage on capacitor C8 through R10 and VR3 of the 3-pin discharge, discharge voltage when the C8 pin 2 when the threshold voltage, E3 reversed so that 7-pin and 3 pin to high, so that a complete oscillation. The audio oscillator output signal Yong Chong CD4066 analog switch integrated circuits added to the first 8-pin, when the E2 pulse of the monostable CD4066 analog switch added to the first 6-pin, the audio signal to switch from analog 8 primers pin to 9-pin sound output to the loudspeakers. The length of sound output from the pulse width E2 decision. That is, one hundred dollars for each pulse, the sound will be issued.

Simple Function Generator with Counter Design

2.6 1 second gate monostable circuit switch

IC E4 by NE555, C9, C10, C11, C12, R12, R13, R14, R15, VR4, and the composition of the button switches the gate AN1 switch circuit, the circuit is actually a switch. In the power supply connected to the moment, due to the voltage on the capacitor C10 is not mutation, E4 of the 4-pin in the reset state by force, so the 3-pin E4 output 0 V, while the 7-pin E4 transistor within the current state of filling in, so C10 No voltage, waiting to press the button to trigger AN1. AN1 button press, as the voltage is not C11 mutation, E4 of the 2-pin voltage was 0 V, when the supply voltage of C11 through R14 rechargeable battery, charging voltage of a rapid increase in the formation of a negative differential signal to the monostable trigger E4, when E4 3-pin and 7 pin is high, 7-pin internal state of the transistor in a way, as a result of the internal 7-pin in the open state of the transistor, power supply voltage through R12 and C10 points to VR4, when the integral voltage E4 When the reset voltage, E4 turned to reset the state, that is, 3-pin and 7 pin at low level, C10 instantaneous voltage on the pin of the 7 discharge, the realization of a single function of steady-state time delay circuit, the output of a pulse and waiting for the next trigger a differential signal, the output pulse 74LS38 integrated circuits used to control doors and non-Article 5 pin to control the function of the pulse signal generator can produce, through the door with the non-arrival of the first 4-pin and The first non-door 6-pin. Threshold pulse width of the door by the time constant C10 (R12 + VR4) decision, that is t = 1.098612 3 (R12 + VR4) C10 decisions, select C10, R12 and VR4 value adjustment to regulate the pulse width t for 1 s. Decimal counter to count input pulse, the count pulse signal ranging from 1 to 99,999; when the threshold of the door at a measurement frequency of monostable state, the function generator can be generated by measuring the frequency of monitoring function in order to signal generator output to the counter signal frequency.

2.7 ICL8038 Function Generator

ICL8038 function generator is a square wave generated at the same time, the triangular wave and sine wave of application-specific integrated circuits. When the rinse section of the external circuit parameters, the availability of adjustable duty cycle rectangular wave and sawtooth wave is widely used in instrumentation. The device's operating frequency can be 0.001 ~ 300 kHz in the framework of regulation, the distortion sine wave output less than 1%, the linear triangle wave output is better than 0.1%. Pulse duty cycle output of the adjustment range of 1 ~ 99%, square wave output level for the 4.2 ~ 28 V, less external components to complete the requirements will be able to function, the use of flexible and adaptable.

This circuit using the supply voltage +15 V, the output of the oscillation frequency f = 0.15 / [(R17 + VR10) C]; R19 networks for internal sine wave conversion of the bias resistors, the use of 82 kΩ; R18 is cited Open Collector 9 resistance of the push and pull the foot; 2-pin output voltage sine wave, 3-pin triangle wave output voltage, square wave output voltage of 9-pin, 11-pin grounding, 7-pin and 8 pin shorted, then 6-pin +15 V . Correct then the above method, using oscilloscope measurements probe pin 2,3,9, and adjust VR10, you can see the changes in the frequency of waveform. To meet the needs of different frequency and voltage range of different requirements and with the load capacity, the output signal using LM324 op amp IC.

ICL8038 function generator square wave output of the 9-pin divided into two, the first pass voltage divider, band switch K6, LM324 3-pin, 1 pin from the output buffer, the buffer played between load and signal source isolation, to meet the needs of the accuracy of measurement; the second counting circuit path (see Figure 2), with the non-gate 74LS38 4-pin, 5 pin is high when the band after a 6-pin and the first switch K1 2 files, on the counter for frequency measurement: ICL8038 function generator of the 2-pin and 3 pin, respectively, the output sine wave and triangular wave, through the LM324 amplifier output through the VR5, VR6, VR8, VR9 adjust potentiometer, the output of different amplitude the sine wave and triangular wave voltage signal, as shown in Figure 3.

Simple Function Generator with Counter Design

3 instruments debug

Equipment should be carried out prior to the use of self-test circuit, first switch K1 band playing in a file, K3 placed low, K4 placed high to start the power supply, pressed the button AN2, to the counter after reset, when light-emitting bright flashing LED D1, E1 note 7 Multivibrator pulse output pin signal role, when the digital control in five seconds under the positive pulse count, and then placed in high K3, any given M1, M2, M3, M4, M5 coding switch settings of the 8421 value, set up after, K3 home with low-level, at this time we can see that the number of counters in the set based on the cumulative count, and then placed in low K4 to carry out subtraction count; K1 under section 2 and then file, and then reset, press the button AN1, when the value displayed is the function of the frequency generator; the K1 file under section 3, with a wire from a square wave the terminal (Figure 3) connected to an external input terminal K1-side (Figure 2), then counter quickly counts, all self-completed, the entire apparatus to normal use.

4 Conclusion

Function Generator with Counter automated production lines in factories, research institutes and universities to be widely used in Physics Laboratory, the instrument function signal generator and counter can be used alone, but also the overall use of the feedback counter slip into any count which can be accessed by the value of alarm sound system, can also be expanded as needed in order to control equipment. This apparatus experiment teaching through the years well.

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