Computer-speech-synthesizer

Description: This text-to-speech converter is constructed using the SP0256-AL2 speech processor and the CF6256AL2 text-to-speech converter chips manufactured by General Instruments. The circuit is designed to receive standard ASCII code from virtually any microcomputer or dumb terminal equipped with an RS-232 port, such as a serial printer or modem port. When a microcomputer is utilized, the synthesizer can be activated from a terminal emulator of any communications program or from any programming language, such as BASIC. The serial input from the RS-232 port enters the circuit through U7, the MC1489 RS-232 receiver chip, which converts the RS-232 level signals to TTL-level signals. The CTS256-AL2 chip, U1, then converts the ASCII characters into allophone codes and sends those codes to U3, the TMS4016 external RAM chip. These codes are subsequently transferred to the SP0256-AL2, U2, via the 74LS373 octal latch, U4. Finally, the SP0256-AL2 outputs an audio signal to the LM386 audio amplifier, U5, through high-pass filtering, and then to the speaker. The 74LS138, U5, and the 74LS04, U6, provide control logic.

The text-to-speech converter circuit is a sophisticated assembly designed to facilitate the conversion of textual data into audible speech. The core components include the SP0256-AL2 speech processor, which is responsible for generating the speech output, and the CF6256AL2 text-to-speech converter, which interprets the incoming ASCII data. The circuit architecture begins with the RS-232 interface, where the MC1489 chip (U7) plays a crucial role in receiving and translating the incoming serial data into a format compatible with the internal logic levels of the circuit.

Once the ASCII data is received, the CTS256-AL2 chip (U1) processes these characters into allophone codes, which represent phonetic components essential for speech synthesis. The use of the TMS4016 external RAM chip (U3) allows for temporary storage of these codes, facilitating smooth data flow to the SP0256-AL2 processor (U2). The 74LS373 octal latch (U4) serves as an intermediary, ensuring that the data is latched correctly before being sent to the speech processor.

The audio output generated by the SP0256-AL2 is then passed through a high-pass filter to eliminate any low-frequency noise, ensuring clarity in the sound produced. The LM386 audio amplifier (U5) amplifies the audio signal, making it suitable for driving a speaker. Control logic is provided by the 74LS138 (U5) and the 74LS04 (U6) chips, which manage the operation of the circuit, allowing for effective coordination between the various components.

Overall, this text-to-speech converter circuit exemplifies a well-integrated design that utilizes established electronic components to achieve the conversion of text into speech, making it a valuable tool for applications requiring audio output from textual data.This text-to-speech converter is built around the SP0256-AL2 speech processor and the Cf6256AL2 text-to-speech converter chips~manufactured by General Instruments. The circuit is set up to receive standard ASCII code from virtually any microcomputer or dumb tenninal that is equipped with an RS-232 port -such as a serial-printer or modem port.

If a microcomputer is used, the synthesizer can be activated from a terminal-emulator of any communications program, or from any programming language such as BASIC. The serial input from the RS-232 port enters the circuit through U7. the MC1489 RS-232 receiver chip, and is converted from an RS-232 level to a TTL-level signal. The CTS256-AL2 chip, Ul, then converts the ASCII characters into allophone codes and sends those codes to U3, the TMS4016 externalRAM chip. The codes are then transferred to the SP0256-AL2, U2, through the 74LS373 octal latch, U4. Finally, the SP0256-AL2 sends out an audio signal to the LM386 audio amplifier, US, through some highpass filtering, and on to the speaker.

The 74LS138d, US, and the 74LS04, U6, provide control logic.