CN2144337Y

CN2144337Y - Digital display electronic sound calibrator for piano

Info

Publication number: CN2144337Y
Application number: CN 92238794
Authority: CN
Inventors: 梁宏
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-31
Filing date: 1992-10-31
Publication date: 1993-10-20
Anticipated expiration: 2002-10-31

Abstract

The utility model relates to a digital display electronic tone calibrator for pianos, which belongs to the technical field of electronic tone calibration, and is used for precise tone calibration for the pianos. The utility model utilizes crystal lattices as high-precision standard basic signals. A microphone is utilized to pick up audio signals sent by the piano. The audio signals are added to a frequency counter after being magnified. The frequency counter exactly counts out frequency of the audio signals. The utility model displays measuring results through a register, a coding driver and LED digitrons finally.

Description

Digital display electronic sound calibrator for piano

The utility model belongs to electronics tuner technical field, especially for piano is carried out accurate tuner.

When piano needs tuner to tune a stringed instrument in the past, the general method that adopts is with reed-type international standard pitch CALIBRATION, and whether consistent, as if inconsistent if utilizing human auditory system to experience the pitch that sound that piano sends and standard pitch CALIBRATION send, then piano is adjusted, to reach the purpose of calibration pitch.This method need be by implementing through the piano tuner of specialized training, is difficult to competent this work without the ordinary people of specialized training.

The purpose of this utility model is exactly the shortcoming that overcomes prior art, provides a kind of numeral to show the piano electronic tonometer, makes the common family that has piano use this product can reach the purpose of doing it yourself to calibrate piano.

We know that the frequency range of audio frequency is 20Hz-20000Hz, and the range scope of piano also is the scope that belongs to audio frequency.In the world the frequency that equals 440Hz is decided to be standard pronunciation, frequency raises one times during than octave of standard pitch; Frequency reduces by one times when hanging down an octave than standard pronunciation; The ratio that faces scale two frequencies mutually is 2 ^1/12, equal 1.05946.The frequency range of the common piano of 88 keys is 27.5Hz-4186Hz by calculating as can be known.The musical alphabet that the concrete musical alphabet and the corresponding relation of frequency can be seen below and the frequency table of comparisons.

We have known the corresponding relation of musical alphabet and frequency, and just available instrument is measured this frequency, so that compare with " musical alphabet and the frequency table of comparisons ", exceed the permissible error scope and just can adjust piano, thereby reach the purpose of calibrating each scale of piano.

The purpose of this utility model realizes by following content: utilize the high crystal of frequency stability and other circuit to constitute the high precision standard time-base signal, pick up the sound signal that piano sends with microphone, after amplifying, add to frequency counter, utilize the standard time-base signal given standard signal (1Hz/ second) come the controlled frequency counter, frequency counter receives the signal from amplifier, frequency counter accurately calculates the frequency of sound signal, through register, decoding-driver, after the LED charactron demonstrates by measured frequency, this frequency is the frequency of piano on this musical alphabet of actual measurement.

The utility model has the advantages that and can carry out tuner to piano simply and easily, precision height, simple in structure is particularly suitable for the ordinary person without specialized training.

Below in conjunction with accompanying drawing, further describe technology contents of the present utility model.Wherein

Fig. 1 is a block diagram of the present utility model;

Fig. 2 is an electrical schematic diagram of the present utility model.

The utility model mainly comprises microphone, amplifier, standard time-base signal, frequency counter, register, decoding-driver, LED charactron, referring to accompanying drawing 2.Wherein the standard time-base signal comprises IC1-IC7, and frequency counter comprises IC8 and IC9, and register comprises IC10 and IC11, and decoding-driver comprises IC12-IC15, and charactron comprises LED1-LED4.Its principle of work is: the 220V civil power obtains the 7.5V alternating voltage after transformer B step-down, and this voltage is exported the DC voltage of about 10.5V after full-bridge QL full-wave rectification, and one the tunnel directly adds to LED charactron positive pole, uses for showing; Another road adds to the input end of three terminal integrated voltage stabilizer 7805, and the positive 5V voltage of output offers other all integrated packages as Vcc after voltage stabilizing.

4MHz crystal JT and IC1(74LS04) to constitute frequency be the oscillator of 4MHz for two phase inverters (3.4,5.6) of hex inverter.Through IC2(74LS00) Sheffer stroke gate (4.6) of 42 input nand gates exports IC3(74LS393 to) two 4 binary counters, the signal of a 1MHz of output behind four frequency divisions.Again through IC4, IC5, IC6(74LS390) obtain the time-base signal of per second 1Hz behind each 100 frequency division of counter, add to 1 pin of IC3, export the Sheffer stroke gate input end 1 of IC2 to from 3 pin of IC3; The sound signal that piano sends is picked up by Electret condenser microphone MIC, the small signal amplifier of forming via transistor Tr is amplified to the required numerical value of Transistor-Transistor Logic level, add to through the Tr amplifying signal on another Sheffer stroke gate 2 pin of IC2, after the IC2 integer, export by 3 pin of IC2, add to IC8, IC9(74LS390) counter, export to IC10, IC11(74LS374 by IC8, IC9 again) register, export to IC12-IC15(74LS47 by IC10, IC11) 4 lines-seven section decoding/driver, again by IC12-IC15 respectively the driving LED charactron show test results.At this moment, the survey frequency scope is 1Hz-9999Hz.Potentiometer W adjusts the amplification quantity of amplifier according to the power of Electret condenser microphone pickoff signals.

IC7 is used for changing the survey frequency scope, to improve measuring accuracy.The signal that IC6 is defeated by IC7 is through IC7 10 frequency divisions again, and this moment, the test frequency scope was 0.1Hz-999.9Hz.The conversion of test specification is by K switch 1 control, and the site that in the time of the conversion testing frequency range radix point of LED charactron moved to left is bright.

Form the start reset circuit by R, C.Start moment, the capacitor C both end voltage can not be suddenlyd change, and can be considered short circuit, makes 11 pin of IC1 connect low level, is output as high level through 10 pin of IC1, adds to IC8, IC9, makes counter O reset.AN is artificial reset button, and the start back all can reset any time.

For the moment that prevents to start shooting shows mistake, by IC17(NE555) and peripheral circuit be connected into monostalbe trigger, at start instantaneous-locking register, prevent wrong the demonstration.

Counter O reset is by IC16(74LS32) 42 inputs or door serve as, and is connected into delay circuit, makes the zero clearing time be slightly larger than signal and squeeze into the time, guarantees to be sent to the correctness of the data of register.

K2 is the test locking switch, when the LED charactron shows measurement result, connects this switch the Sheffer stroke gate input end 5 of IC2 is connect low level, and the 6 pin no-outputs of IC2 make the LED charactron show locking, are convenient to the gauger and observe.

Numeral of the present utility model shows that the piano electronic tonometer uses the 220V/50Hz power supply, and its measurable frequency range is 0.1Hz-9999Hz, and divides second gear, and first grade is 0.1Hz-999.9Hz, and second grade is 1Hz-9999Hz.

After CALIBRATION inserted the 220V power supply, the energized K switch was with the MIC(microphone) put into piano qin case, by " musical alphabet and the frequency table of comparisons " selection range; Press piano key, just can read display result from the LED charactron this moment, knows the tone of piano from its result, thereby piano is tuned a stringed instrument, until having calibrated tone.

The musical alphabet and the frequency table of comparisons (cps is Hz)

Claims

1, a kind of numeral shows the piano electronic tonometer, it is characterized in that it comprises microphone, amplifier, the standard time-base signal, frequency counter, register, decoding-driver, the LED charactron, wherein pick up the sound signal that piano sends with microphone, after amplifying, add to frequency counter, utilize the standard time-base signal given standard signal come the controlled frequency counter, make the signal of frequency counter reception from amplifier, frequency counter accurately calculates the frequency of sound signal, through register, decoding-driver, after the LED charactron demonstrate by measured frequency.

2, numeral according to claim 1 shows the piano electronic tonometer, it is characterized in that the standard time-base signal comprises IC1-IC7, frequency counter comprises IC8 and IC9, and register comprises IC10 and IC11, decoding-driver comprises IC12-IC15, and charactron comprises LED1-LED4.

3, numeral according to claim 1 shows the piano electronic tonometer, it is characterized in that the potentiometer W in the amplifier adjusts the amplification quantity of amplifier according to the power of Electret condenser microphone pickoff signals.

4, numeral according to claim 1 shows the piano electronic tonometer, it is characterized in that its survey frequency scope is 0.1Hz-9999Hz, and divides second gear, and first grade is 0.1Hz-999.9Hz, and second grade is 1Hz-9999Hz.