Saturday 11 July 2015

How To Build a Digital Voice Changer Circuit

The publish describes a circuit which includes the capability to modify or transform an individuals unique voice into a totally new form.

The feature tone of each and every individuals voice is particularly different in all situations. How many times we attain a phone call and as a result of listening our interlocutor has the capacity to understand instantly who it is on the other side.
In several events you can easily identify the existence of somebody in a group or in a occasion by way of hearing to his or her voice, without even viewing the individual.
Can you be interested to change the timbre of a person's voice at will and make it seem to be totally different to other people? Or modify it even like a robot or a being from some another planet?
The suggested digital voice changer circuit is precisely manufactured to achieve this for you, and quite a lot more.
Depending on a voice modulator technology from HOLTEK, this voice changer chip digitally processes the fed voice signal instantly.
It does this by shifting the frequency spectrum connected with the voice therewith, upwards or downwards in seven incremental measures along with the subsequent output is noticed as fairly much thinner or thicker in its frequency.
The outcome may be compared to that acquired a playback speed of a vocal information recorded on a tape is increased or decreased, except that it does without disturbing or distorting the sped of the speech, furthermore moreover it provides two unique sound effects: vibrato and robot to a sample speech.
The first characteristic within the two transforms your voice with more tremulous while the second affects it simulating a robot kind of voice.
In spite of this under both the outputs the voice is fed to the IC by means of a regular electret microphone and the dimensioned output is reproduced by means of a dynamic speaker.
The complete system works from a 9V battery.


Digital Voice Changer Circuit


The HT8950 contains, among other useful blocks of an amplifier with internal polarization microphone, an A / D of 8 bits, a static RAM (SRAM) and a D / A converter 8 bits. The A / D and D / A work at a sampling rate of 8Khz, a sufficient amount to take care of the spectrum of the human voice (3Khz) and offers an output quality and extremely high signal to noise ratio (SNR).The following table summarizes the function of each pin for HT8950A version.No. NAME FUNCTION1 OSC1 input of the oscillator2 VIB input mode selector vibrato3 TGU step input selector UP4 TGD input selector step DOWN5 ROB Input Selector mode step ROBOT6 VSS negative supply line (GND)7 NC Not connected8 A0 output internal amplifier9 AIN input of the internal amplifier10 VDD Positive Power Line11 LED LAMP Output for volume12 AUDIO Audio Output13 VREF Reference voltage internal amplifier14 TS chip test input15 FVIB control output frequency vibrato16 OSC2 output of the oscillatorIn Figure 2, the schematic diagram of the digital voice changer demonstrated. The system is made up fundamentally of a digital voice modulator and an audio amplifier, designed around respectively the chip IC1 (HT8950A) and IC2 (LM386I) the user's voice is caught by an electret microphone (MIC1) and reproduced typically or frequency offset in a dynamic speaker (SPK1). The whole assembly functions from a 9V battery (B1).
After being grabbed by the microphone, the voice signal is placed on the internal amplifier HT8950 by means of R4 C2 network. The voltage acquire of this amplifier, that could be an open loop is usually equivalent to 2000, identified R3 (feedback resistor) and R4 (input resistance), being of the order of 8.3 times. Resistors R5 and R7, along with the capacitor C4, the biasing situations supply the electret element.An amplified and limited in bandwidth time, the injected HT8950 voice signal to the A / D bits where internal 8 is digitized at a nominal sampling rate of 8Khz. The sampling signal generator generates a time base, in turn managed by an oscillator. The frequency of the latter, which is about 512Khz, is dependent upon R2.After digitized voice signal is stored in a static RAM (SRAM), also managed by the time base generator, a control circuit removes data from the RAM and transferred to a latching register. From the latter, the speech signal goes to a D / A converter the 8-bit reset to its original analog form or shifted frequency spectrum. This signal can be obtained on the AUDIO output (pin 12).Depending on the speed with which the SRAM data to the D / A are provided, the original signal is reproduced with or without offset frequency spectrum. This problem is determined by the chosen step by push-button switches S2 type (UP) and S3 (DOWN). Particularly, with every touch, move the speech spectrum S2 step up and S3 moves it a step down. In both instances, the series is routinely continued, as demonstrated in Figure 3.
Once transformed to its analog form, the speech signal is utilized through C3 R8-network to a LM386 (IC2) amplifier, accountable for leading the speaker (SPK1) thereby making it audible. The resistor R6 works like a pull-down of the D / A HT8950 internal current mode and trimmer R9 as master volume control system. Other elements follow auxiliary features. D1 especially restricts the supply voltage to a safe value HT8950 (below 2.8V) and R1 vibrato frequency fixed at 8 Hz, somewhere around.
List of Materials
Resistance (1 / 4W 5%)
R1-100K
R2-47K
R3-39K
R4, R5, R6-4,7K
R7-470
R8-8,2K
R9-5K, Trimmer, 1 lap
Capacitors
C1-4,7uF / 16V electrolytic
C2-0,47uF (474), ceramic
C3, C5-0,1uF (104), ceramic.
C4, C6, C7-220uF / 16V, electrolytic.
Semiconductors
Zener diode D1-6,2V / 0.5W
Integrated CircuitsModulator voice IC1- HT8950A
IC2- LM386 audio amplifier
Transducers MIC1- electret microphone, miniature
SPK1- Speaker 8 / 0.25W
Electromechanical
S1,..., S4-push-button switches Miniature NAJ1- type connector for 9V battery snap.


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