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MagaZine - Free and Open Source Software

Robert A Nickels WAOOHO

Bt)] 5. Mmle 51.

Kimbd ll Nt 69145

Build a Frequency Counter


- state-of-the-art for blind hams

The availability of lowcost

speech synthesizer

technology has o pe ned

many doors fo r the sightless

amateur. The introduct ion

of a "talking calculator"

severa l years ago was the

first and most affordable

example of synthesized

speech inst ruments which

are useful to the visuallyhandicapped


Photo A. There is little evidence that this 05/ Model (.700 frequenc y counter has a voice of

its own. The push-button in the left-hand corner of the cabinet top triggers an a-digit

reado ut. Volume and audio-visual controls are on rea r panel.

Through the courtesy of

the manufacturer, Telesensory

Systems, Inc., of Palo

Alto, California, the heart

(or, mo re appropriately, the

voiceboxl of the Speech

Plus Calculator re ce nt ly

has been ma de available at

a reason able price. Since

that t ime, severa l efforts

have been made to interface

this module to avai l­

able amateur equipment.

Most have been relatively

complicated, req uiring from

10 to 30 or more IC packages.

Thanks to the forethought

of the designers, a

simple and very easy to

duplicate interface is possible,

eliminating a major

ba rrie, to more widespread

use of synthesized speech

in d igital equipment. The

m od el C-700 frequency

counter, manufactured by

DSI Inst rume nts of San

Diego, Ca li fo rnia, is based

upon the LSI Com puter Syste

ms LS 7031 counter IC,

which is ideal for this applicatio

n. Othe r test equipment

may be connected to

the synthes izer module in a

similar manner. The only

52 73 Magazine · April, 1981

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