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Circuit Archives
Speech & Music/ Synthesis
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Computer Speech Synthesizer
Reprinted with permission
from Rudolf Graf.
For this and over 1000 other electronic circuits, review and order Rudolf
Graf's Encyclopedia of Electronic Circuits on CD-ROM Vol-1
McGraw-Hill ISBN0078528119
For a full size schematic of this
circuit, view the PDF file version here. (You must have a
copy of Adobe Acrobat Reader to view this file.)
FC120-3
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Description:
This text-to-speech
converter is built around the SPO256-AL2 speech processor and the CT6256- AL2
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 terminal 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, U1, then converts the ASCII
characters into allophone codes and sends those codes to U3, the TMS4016 external-RAM
chip. The codes are then transferred to the SPO256-AL2, U2, through the 74LS373 octal
latch, U4. Finally, the SPO256-AL2 sends out an audio signal to the LM386 audio amplifier,
U8, through some high-pass filtering, and on to the speaker. The 74LS138d, U5, and the
74LSO4, U6, provide control logic. (Hands-On Electronics, 10/88, p. 30.and figure FC120-3
from Encyclopedia of Electronic Circuits Vol. 1.)
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