Auditory Breakout Box Battery Testers: Auditory Battery Tester Carpentry: Audible Carpenter's Level Digitized Speech Technology Magnetic Tape Accessories: Meters and Meter Readers: Audible Meter Reader Micrometers: Refrigeration Repair: Talking Refrigeration Pressure Gauge SKERF-Pad Screen Access System Soldering: Solder Guides
Auditory equivalent of visual "breakout box" for interconnecting computer components via the RS-232 serial interface. The RS-232C "standard" has been so liberalized over two historical decades that plugging in computer peripherals often requires special tailoring of the cables. Computer technicians use a test instrument called a "breakout box" to ferret out the proper connections. Contained in one package, this instrument has two functionally separate parts. The first is a patch panel of plugs and jacks which allows the user to create individual wiring schemes for the serial RS-232C computer interface. By changing connections on the patch panel, the "transmit" and "receive" data lines, as well as the handshaking lines, can be matched as necessary. This patch panel is not unusual for breakout boxes except for the fact that the jacks are arranged in the same physical shape as the commonly used 25-pin plugs and sockets, so that no numbering system need be devised for the blind user. The other component of the Breakout Box is comprised of two audible logic probes which, by a simple language of tones, substitute for red and green LEDs on visual breakout boxes. By probing various terminals on the patch panel, the blind user can find the status of various lines as follows: (1) a high-pitched tone indicates a logic "high" such as would be present on a printer's handshaking output; (2) a medium-pitched tone indicates a logic "low" such as would be heard from a "transmit data" line; (3) a low-pitched wavering tone indicates that the line being sensed is uncommitted; and (4) a low-pitched steady tone indicates a line which is either grounded or which awaits manipulation by a handshaking or data output. The two logic probes allow two lines to be monitored simultaneously. For example, the exchange between data transmission and handshaking operations can be "watched." The Auditory Breakout Box is a useful tool for blind computer users and technicians who are involved in assembling complete computer systems using widely disparate components and peripherals. Availability This instrument can be obtained through the Smith-Kettlewell Rehabilitation Engineering Service. Cost is $295. Provides auditory detection and monitoring of serial computer data transmission. Originally called the "Transmission-in-Progress Alarm," this device provides a blind computer user with an audible indication of serial transmission (primarily from a modem, but also from the computer to printers and other peripherals). It was developed in collaboration with the Research and Development Committee of the National Federation of the Blind. (Two early prototypes were made by Smith-Kettlewell, and a subsequent production model was designed and made available by a private vendor in Kentucky.) Accessing the screen to assess the progress of transmission interrupts the computer and slows down its communication. The Tweedle-Dump "tweedles" (makes small beeping noises) whenever there is communication over the serial port. This device has many useful applications, including the provision of reassurance to a blind computer operator that such functions as transmission of data to a printer's buffer is proceeding as it should -- while the computer itself may appear to be inactive for a lengthy period. Also, knowing when data transmissions over expensive telephone hookups are finished can amount to real cash savings. Availability The commercial Tweedle-Dump is a low-cost device which looks like an adapter for RS-232 25-pin connectors. It is available from Mr. John Monarch, 525 Pawnee Trail, Frankfort, KY 40601, telephone (502) 695-1761. The price is $16. The device is also available from Blazie Engineering, 105 East Jarrettsville Road, Forest Hill, MD, telephone 410-893-9333. Allows use of an oscilloscope to measure waveforms without vision, using auditory feedback. Depending upon the oscilloscope model being used, the adaptive circuitry can either be internal or attached externally to the scope. The user manually operates a horizontal scanning control which "describes" the vertical excursions of the waveform on the screen using variations in pitch. The position of the scanning control represents the position of a pointer on the horizontal axis, while the pitch of the audible tone represents its position on the vertical axis. The auditory oscilloscope can be used by blind engineers, technicians, hobbyists, and students to give them access to waveform information which is generally available only to sighted users. The inclusion of this device would be invaluable in the laboratory, workshop, and classroom where the preponderance of visual displays put persons with sensory disabilities at a special disadvantage. Availability The auditory oscilloscope is available from Oehm Electronics, 2194C Galveston Avenue, San Jose, CA 95122, telephone (408) 971-6250. Cost varies according to the type of oscilloscope adapted, and ranges from $2,500 to $9,500 including the oscilloscope. User Comments "The auditory adapter enables me to quickly and accurately make measurements on any signal and observe waveform characteristics of any AC signal voltage. This device is very ingenious, innovative, and useful. It is a necessity in the electronics industry, and my very livelihood depends upon performing the tasks that this instrument enables me to do. It's a unique invention ... opens many employment possibilities for blind persons ..." R. O., Electronics Technician, Palo Alto, CA This instrument tests flashlight cells of all sizes, as well as 9-volt batteries. Published as "The Smith-Kettlewell Auditory Battery Tester" (The Smith-Kettlewell Technical File, Winter 1990) the cell (or 9-volt battery) under test is compared with a voltage standard. The condition of the cell is indicated by the duration of beeps; a fresh alkaline cell causes the device to emit very short pips or to fall silent, while one which is declared "dead" causes a steady tone to be produced. Beeping whose duration is "half-on/half-off" means that there is still useful life in a cell, but it is not fresh. (Nicad cells, supplying 1.25 volts when fully charged, produce the "half-on/half-off" indication when they are freshly charged.) In other words, the shorter the beeps, the better the cell. Two configurations are documented: One uses our electronics added onto a Radio Shack "Handy Checker," Cat. No. 22-096, which has a conventional visual meter. The second approach is to build the auditory instrument from scratch, thus making it independent of the availability of commercial products. Be they tape recorders or medical instruments, users often need to have a precise indication of battery condition. With the advent of fairly accurate visual indicators built into packaging of batteries, the sighted consumer can get this information readily. In contrast, "audible battery testers," as marketed through suppliers of equipment for the blind, are generally "go/no-go" buzzers which indicate little about battery capacity. A true test of battery condition requires that cell voltage be quantitatively measured under load. A voltmeter, by itself, only shows the open-circuit cell voltage; how it will behave when it is put to use is not shown by a voltmeter. On the other hand, a "go/no-go" test, simply powering a buzzer or a lamp, says only that the cell can run the test device; this gives no information about capacity that is left, or how the cell may perform in service. Our device, by comparing the cell's voltage under load with a standard voltage, gives the user a good idea of the cell's capacity by the duration of the signals, and it does so as the cell is subjected to a realistic load (not merely a buzzer, but a load as might be presented by a more critical electronic device). Availability The battery tester is available at cost from our Rehabilitation Engineering Service. An adaptation of a visual instrument for testing hearing-aid batteries -- typically "zinc-air" button cells. A visual button-cell tester, made by the Duracell/Activair Company in Bethel, Connecticut, was equipped with additional electronics containing a voltage standard with which the cell under test was compared. Two outputs were provided on the prototype: one used a buzzer whose vibration could be felt as well as heard. The other output was a jack, fed by a 250Hz oscillator, into which an earphone could be plugged, or by which a small loudspeaker (used as a vibrator) could be attached. (The on-off response of resonant buzzers, usually tuned cantilever types, is slow, and it was felt that the speaker/oscillator combination might lead to more accurate readings. However, follow-up inquiries revealed that the user evaluating our prototype used the buzzer and didn't bother with the external speaker.) Battery condition is indicated by the duration of "buzzes" (felt as vibrations). A cell which is declared "dead" gives a constant vibration; the better the cell, the shorter the pulsations. A good cell may cause the device to fall dormant -- no pulsations at all. A true test of battery condition requires that cell voltage be quantitatively measured under load. A voltmeter, by itself, only shows the open-circuit cell voltage; how it will behave when it is put to use is not shown by a voltmeter. On the other hand, a "go/no-go" test, simply powering a buzzer or a lamp, says only that the cell can run the test device; this gives no information about capacity that is left, or how the cell may perform in service. Our device, by comparing the cell's voltage under load with a standard voltage, gives the user a good idea of the cell's capacity by the duration of the signals, and it does so as the cell is subjected to a realistic load (not a high-current buzzer, but a load as might be presented by a hearing aid). Availability The battery tester can be made available at cost from our Rehabilitation Engineering Service. For home/professional carpentry -- mounting shelves, erecting fence rails, cabinet work, or framing buildings. Our instrument, published as "The Smith-Kettlewell Audible Carpenter's Level Built from Scratch" (The Smith-Kettlewell Technical File, Vol. 13, No. 2) is based on a "tilt sensor" marketed by the Midori America Corporation in Fullerton, California. This sensor, a pendulum attached to a magnet in proximity to solid-state "magneto-resistive" material, is mounted on the "beam" (rail) of a commercial level. Circuitry presents relative position of the pendulum by way of a variable-frequency tone. A comparator detects the desired "level" position of the pendulum. Tilting in one direction produces a smooth tone whose pitch gets lower in proportion to deviation from "level"; tilt in the opposite direction produces an interrupted tone (chopped at a rate of perhaps 3 times per second) whose pitch increases in proportion to tilt. The range of the Midori pendulum device is limited to 20 degrees, so if both vertical and horizontal instruments are desired, two Midori sensors must be employed. An accurate carpenter's level is a basic tool. Visual ones have a glass vial in which an air bubble can be observed and aligned with markings. The Smith-Kettlewell Audible Carpenter's Level, unlike other audible electronic levels, gives a precise indication of the "level" condition. (Other electronic instruments provide a "window" -- a space between two tones or a tone to indicate level -- which may span several minutes of a degree.) Furthermore, our design presents the user with pitch information which is proportional to the amount of deviation from being level; thus, in adjusting a shelf or beam, the builder knows which way to move to achieve the desired position. Availability The carpenter's level involves some mechanical packaging work, increasing its production expense in small quantities. However, persons interested in obtaining one may contact our Rehabilitation Engineering Service. Duplicates the function of a carpenter's steel measuring tape, for measuring wood, furniture, rooms, spaces and other flat physical objects. The Rooller is a box measuring 7 x 10 x 2 inches and has a rubber wheel mounted on a spring protruding through its bottom. The top contains a 16-key pad, speaker, and other controls. The end of the box contains a sliding "fence" to guide the operator in making straight measurements. The Rooller can be placed on any flat surface and started with a button. It is then rolled along until its edge matches a feature to be measured. When another button is pressed, the device announces the distance traveled in feet and inches or in meters. The use of a microcontroller allows the user to enter measurements and to have the Rooller "find" the preset measurement through use of a varying tone output which changes as the Rooller is moved. This and other features make many household and carpentry measurements easy and accurate. The recent commercial availability of measuring tapes with (visual) digital readout systems may make it possible to produce a second-generation device by connecting the computer and speech systems of the Rooller to the sensors of the commercial tape. This device, based on the previously described low-cost computer technology, demonstrates how both static information, as in an unchanging measurement, and dynamic information such as approaching a preset measure while moving the Rooller, can be made readily accessible with properly programmed microcontrollers at relatively low cost. The electronics of the Rooller cost approximately $150, although this prototype required the additional expense of custom machining work. The techniques demonstrated here are readily adapted to a wide variety of measurement applications. Such techniques may have use for sighted workers who may find it desirable to "hear" measurements while looking at work in progress. Availability Although not presently available, this device is included here to demonstrate the type of adaptive equipment which can be and has been developed to solve specialized rehabilitation problems. Persons interested in finding solutions to similar problems may contact the RERC lab for technical advice and/or referral. Allows a blind handyman or carpenter to locate studs in a wall. The Zircon "Stud Sensor" (also marketed by Radio Shack as the "Archer Studfinder") is a sophisticated electronic device whose indications of hidden structures are not subtle. It is a relative capacitance meter which senses these structures by their capacitance effect; it presents these relative indications to a sighted user via a column of LEDs. We developed an auditory version by locating a "relative capacitance" analog signal which can be used to drive a voltage-controlled oscillator (VCO). Thus, with our modified instrument, the blind user hears a distinct rise in pitch when the capacitance increases -- which happens when a stud is found. A common problem encountered by custom cabinet makers, as well as individual homemakers, is finding the structural members within walls ("studs") onto which heavy shelves and wall hangings can be mounted. There have been many devices for finding studs, but these are traditionally visual instruments. We have successfully modified a commercial stud finder so as to present auditory feedback to the blind cabinet maker and handyman. Availability Our modifications to the original Zircon instrument have been published in the Smith-Kettlewell Technical File, and were transmitted to the manufacturer. Individuals who have made their own from our design have applauded the instrument's utility. Zircon has now added a simplified "go/no-go" auditory output to the commercial version of the instrument, which is available at hardware stores and Radio Shack. A low-cost digitized speech system for adaptive devices, independent of proprietary technology. Many adaptive instruments require spoken output having only a relatively limited vocabulary. Since most instruments read out numbers, often all that is required are the 10 digits, and perhaps "point." Even where names of units or scaling factors are needed, the number of words required is usually limited to no more than 50. For this reason synthesized speech technology is not appropriate since the minimum cost for a speech synthesizer with text-to-speech capabilities is $150. Also, even with the best synthetic speech available, digitized speech is usually clearer and more easily understood under noisy work situations. The speech recording technology developed at the Smith-Kettlewell Rehabilitation Engineering Research Center uses commonly available components. Playback devices in systems already containing a microcontroller consist of additional EPROM memory and a simple audio amplifier and filter system. Adaptive instruments (exemplified by several in this compendium) contain vocabularies of up to 35 words at a component cost of less than $20 over that of the computer and sensors necessary to obtain the information to be spoken. Even with the introduction of inexpensive speech recording chips by Information Storage Devices, many applications are more easily adapted using Smith-Kettlewell's speech recording system because it is more easily controlled by the computer than are the ISD devices. This speech recording technology is applicable to any adaptive device which requires only a limited vocabulary (the practical vocabulary limit is in the region of 100 words). The system is especially appropriate where a microcontroller is required to interpret the information to be made accessible, since playback of speech using the Smith-Kettlewell system requires very little added hardware beyond computer memory and a simple audio filter/amplifier. This technology requires relatively little power, making it quite applicable to portable battery-powered applications. An additional advantage of this technology is its independence from proprietary speech chips whose availability and features change with time, necessitating periodic re-designs of adapted equipment. Availability The designs (both hardware and software are in the public domain) are available from Smith-Kettlewell. These techniques will be used as appropriate by Smith-Kettlewell staff in developing customized designs for adaptive equipment. This technology is included here to demonstrate the type of adaptive equipment which can be and has been developed to solve specialized rehabilitation problems. Persons interested in finding solutions to similar problems may contact the RERC lab for technical advice and/or referral. Assisting blind entrepreneurs in the establishment and operation of a private FM radio station. Our RERC has been involved in the development of various technical solutions for both professional and amateur radio operators. The project described here was designed to assist two blind entrepreneurs in their establishment and operation of a private FM radio station in the rural community of Goldendale, Washington. Solutions were developed for problems such as the recording of repetitive announcements and hard disk files for on-air access by a scheduling program (most of the available software interfaces for these purposes are graphical in nature, and must be modified for use by the blind announcers). The operators use a braille embosser to make scripts of commercials and daily log sheets. Technical changes require replacing tape cartridge players with hard drive files, routine station breaks with indexed files, and satellite music systems with programmable CD players. It is intended that this project be a model for small-town broadcasting that will be a benefit to other blind entrepreneurs wishing to establish similar businesses. Availability A manual covering the necessary steps and technical aspects is in preparation and will be made available in different formats. Additional information can be obtained by calling Mr. William Loughborough at (509) 773-5958. Provides a blind business owner with the "row count" information on a knitting machine. The existing knitting machine is used by a partially sighted woman who manufactures knitted items in a small business. The machine is equipped with a mechanical counter which counts passes of the machine's shuttle. The mechanical counter is not readily adaptable to electrical reading. In this example, it was necessary to place a small magnetic switch on the machine and a small magnet on the moving shuttle. A microcontroller-based talking counter was developed into which the magnetic switch was plugged. This counter not only can be made to announce the current row count, but can be preset to alert the operator when a preset numbered row is reached. The device contains battery-backed memory so that the count and other information are not lost when the equipment is turned off. This means that the operator is not forced to remember where she left off at the end of her work period. The counter is contained in a plastic box measuring approximately 4-1/2 x 7 x 2-1/2 inches. It contains a 16-button keypad for entering numbers and controlling its functions. There is also a volume control, on/off switch, speaker and earphone jack. The device can be operated from an external AC power supply or from an internal 9-volt battery. As an added feature, the device can be made to act as a mileage counter for an exercise bicycle by simply attaching a magnetic switch to the frame, and a magnet to the wheel. The computer can be switched between knitting counter and bicycle odometer with a single button press. Availability Although not presently available, this device is included here to demonstrate the type of adaptive equipment which can be and has been developed to solve specialized rehabilitation problems. Persons interested in finding solutions to similar problems may contact the RERC lab for technical advice and/or referral. For auditory alignment of tape heads to assure proper phase relations between stereo tracks. Where half-track open-reel tapes are issued to individual broadcast stations, the azimuth of the playback head is critical for assuring that the two stereo channels are in phase. Otherwise, the monaural listener would hear diminished quality audio. The unit is connected to the tape recorder and compares the tone signals from both channels. It presents any difference in the phase of the channels to the user as an audible tone. The user then adjusts the playback azimuth for the complete cancellation of the tone. As technologies for transcribed broadcasts progress, alignment systems will no longer be critical. This device can be used in broadcast station installations where stereo tapes contain a tone by which a sighted engineer normally adjusts tape head azimuth using an oscilloscope. It is specific to the stereo broadcasting industry and can be used by sighted as well as blind engineers. Availability Schematics are available from the RERC office. For marking portions of tape-recorded material for future reference. An inaudible tone is superimposed onto material that is being recorded, which can later be heard during fast scanning of the tape (rewind or fast forward).The unit can be plugged into the microphone jack of any tape recorder. It has both low and high level inputs allowing the program to be recorded either using a microphone or from another tape machine. The tone can be entered onto the tape by pressing a button on the device. The unit allows the use of a remote control microphone to start and stop the tape machine. In addition, the remote switch on the microphone can be connected in parallel with the indexing pushbutton switch, permitting indexing to be done with the switch on the microphone. While the use of cassette tape recorders has become widespread among the blind, the utility of these devices has been limited due to the slow speed of access to the stored material. This device has general applications for anyone using tape recorders, as important points made in classroom discussions, chapter headings in text material, etc. can all be flagged for speedy retrieval. Availability Schematics are available from the RERC office. User Comments "I use this daily and have found it to be very reliable ... it puts the tone on the tapes where needed." D.R., Everett, WA Provides an auditory alternative to using a visual moving pointer meter. The unit is self-contained and acts as an accessory to existing equipment. Its input can be wired to the terminals on the back of the visual meter movement. The user merely rotates a pointer knob until a null in an auditory tone is heard. At this point the reading is taken from a braille scale surrounding the pointer knob. As this meter may act as a substitute for any pointer meter and requires a minimum modification of existing equipment, its applications are widespread. It has been used extensively to adapt automotive test equipment and industrial work stations for use by the blind. It is particularly useful to blind scientists, engineers, electronics technicians, hobbyists, and others who use analog meters. [Note: See also "Dynamic Meter Reader" in Section II for a different type of audible meter reader especially suited to measuring varying signals.] Availability Schematics are available from the RERC office. Construction plans and a circuit description were published in the Spring 1981 issue of the Smith-Kettlewell Technical File, also available from the RERC. Some tooling is required for the braille scales utilized in the device, or the scales can be provided by the RERC. This meter monitors sound levels in broadcasting and recording equipment. The user is provided with auditory feedback to signal the presence of excessive levels of sound. The unit plugs into a standard monitor jack on existing equipment. A variable frequency tone is presented for each "track"; typically two-channel units are used to monitor the two channels suspected of having the highest levels. The tone begins at a low frequency at 0 vu, and the pitch increases with sound levels exceeding this. This device can be used in the broadcasting and recording industries as well as in high-quality home recorders. This indicator may also be used by the sighted, for it allows the monitoring of sound levels without the need for constant attention to a visual display. Availability Schematics are available from the RERC office. Special tooling or subcontracting required for tactile version. Construction plans and a circuit description appear in the 1981 Winter and Spring issues of the Smith-Kettlewell Technical File, also available from the RERC. A commercial version is available from Oehm Electronics, 2194C Galveston Avenue, San Jose, CA 95122, telephone (408) 971-6250. A general-purpose meter for measuring volts, ohms, and milliamps. The Smith-Kettlewell "Talk-&-Tones" multimeter integrates both speech and dynamic tonal outputs in a versatile test instrument for electronics. For static "quantitative" measurement, its output is announced in digitized (recorded) speech, stored in conventional static RAM. Dynamic readings -- changes as adjustments are made, or fluctuations as intermittent conditions are being repaired -- are indicated by a variable-frequency oscillator. An adjustable voltage standard, which can be set with a calibrated braille dial, can be set by the user to mark a desired quantity; this is particularly useful when making an adjustment to attain a certain reading. Quantities exceeding the setting of the braille dial cause the output of the variable-frequency oscillator to be interrupted 3 times per second. Thus, pitch information is still apparent, but the "chopped" nature of the tone indicates that a setting has been exceeded. The volt/ohm/milliammeter (VOM) is a basic tool in electronics work. There are two types of visual meters: "analog" and "digital" ("moving needle" and numeric) displays. With the latter, a fixed quantity can be read via a numeric display. With a varying quantity (as an adjustment is made), the dizzying fluctuation of numbers is often unusable, and a "moving needle" is preferred by the technician. Beyond the traditional view, the blind technician uses test instruments for nontraditional assessment. Tracing circuits -- aided by colored wiring and by visual inspection of "traces" on boards -- is often accomplished by blind technicians with dynamic metering equipment. Noting the presence of noise, or intermittent connections, or signals, on lines assumed to carry only static voltages requires an output that can indicate change. For example, quality-control faults, faulty solder connections and broken wiring are found using dynamic metering by the blind technician, rather than discovering them by visual inspection. Thus, the variable frequency oscillator is preserved as an analog indicator. Since spoken numeric displays are notably slow, "leading zero suppression" is provided; only significant digits are spoken. Powers of ten are expressed by a change in pitch of the voice. The Talk-&-Tones meter also incorporates separate input circuits for voltage, current, and resistance. Unlike other multimeters, this allows the instrument to remain connected to separate circuits while work is being done elsewhere. Part of the impetus for creating the Talk-&-Tones was that accessible multimeters, talking or not, come and go on the market. As documented, this device will lend itself to fabrication from off-the-shelf parts. On the other hand, it is a complex instrument involving nearly three dozen integrated circuit chips. We see the importance of the Talk-&-Tones in two ways: First, it is a fall-back device when alternatives are not available. Of more significance is its exemplary integration of a dynamic output with the pushbutton access to speech, which may be useful in other applications. Availability The Fall 1989 Smith-Kettlewell Technical File contains construction plans and a circuit description, and is available from the RERC office. An adapted electronic dial micrometer for making very precise dynamic and static measurements. A linear variable differential transformer (LVDT) senses the position of a spring-loaded plunger. The LVDT produces an electrical output in proportion to the displacement of the plunger. The resultant electrical signal is fed to an audible electrical measurement circuit. In order to determine the position of the plunger, the operator turns a precision potentiometer control knob until the tone reaches a peak frequency. Plunger position is then indicated on a braille scale. Changes as small as 1/10,000 of an inch can readily be detected using the auditory feedback, and the tactile scale can be calibrated as precisely as the visual display of a comparable instrument. For use by blind machinists, machine operators, students, etc. Lathe operators may use it to center material placed in a lathe and detect asymmetries in diameter. Can also be used in aligning the lathe for operation. Has applications to quality control and inspection tasks. Availability Schematics are available from the RERC office. User Comments "I could not use the instrument this micrometer is attached to without it ... invaluable ... very reliable. Dial is large and easy to work with." R. L., Machinist, Santa Clara, CA For general use in making precision measurements of mechanical dimensions. This is a standard mechanical micrometer which has been adapted with an expanded braille scale. The scale is on a drum whose diameter is larger than the "thimble" on which visual markings are inscribed. Can be used by blind machinists, automotive repair technicians, piano tuners, electronics and fabrications technicians, etc. Availability Plans are available from the RERC office. Machining of materials is required. User Comments "This excellent instrument should be marketed. It has no peer ..." T. C., Administrator, Frankfurt, KY "Very excellent for close readings ... I wouldn't like to be without it ..." R. L., Machinist, Santa Clara, CA "Other adapted micrometers require me to line up markings of the thimble with a groove on the "cylinder." Unfortunately, a shoulder on the frame of these instruments means that measurements cannot accurately be made for small distances; the shoulder gets in the way of my fingernail. As a piano technician, I am interested in measuring small-diameter string wire, and the Smith-Kettlewell micrometer is the only one that allows precision at these distances." W. G., part-time piano technician, San Francisco, CA Provides an audible alerting signal when a silent visitor steps and remains standing on an electric switch mat. Electric switch mats (commercially available in various sizes) are adapted by connecting the mat to an "alert box" of our design. The mat may be placed under existing carpet or throw rug. Normal walking over the mat does not cause a signal to be emitted from the alert box, and it is only when a visitor stands on the mat for a predetermined length of time (usually a few seconds) that a short, soft beep is heard. In a clerical setting, the mat can be placed in front of a receptionist's desk, so that when a visitor steps and remains standing on the mat, the receptionist will be alerted to his or her presence by an audible signal. This is especially helpful in situations where visitors do not immediately signal their presence to the receptionist. This device is also useful to cashiers at a vending stand (where it may double as a simple security system) or to anyone else dealing with the public. Availability Schematics are available from the RERC office. Construction plans and a circuit description appeared in the Winter 1983 Smith-Kettlewell Technical File (also available from the RERC). Allows a blind appliance repairman to measure several important parameters required in the repair of refrigeration equipment. This device is an example of an instrument based on a single-board microcomputer. It was developed at the request of Mr. Randy Brooks, the owner of an appliance repair shop in southern California. It is used in his work both as an aid in actually making repairs to refrigerator and air conditioning equipment, and to assist him in training new technicians in the business. It measures three quantities associated with this work: 1. High refrigerant pressure, up to 300 p.s.i. These measurements are required for testing, evaluation, repair and "recharging" of both home and commercial refrigerators, freezers and air conditioners. As mentioned above, this machine allows the operator to be a successful, independent businessman. It makes the difference between total dependence on sighted technicians and the ability to teach these sighted workers to use their visual instruments. Note: This device exemplifies the need to develop an entirely independent measurement system for the pressure quantities because the visual gauges used at the time of development were entirely mechanical and could not readily be "read." On the other hand, the commercial refrigerant scale was adaptable because it was possible to obtain a voltage which related to the weight information with relatively little modification of the commercial unit. The use of a microprocessor in the talking machine made it practical to read both the newly designed pressure gauges and the voltage from the adapted scale. The principles of this device's design could be readily adapted to modern computer and speech systems as described in Talking Instruments Using Single-Board Computers. Availability Although not presently commercially available, this technology is included here to demonstrate the type of adaptive equipment which can be and has been developed to solve specialized rehabilitation problems. Persons interested in finding solutions to similar problems may contact the RERC lab for technical advice and/or referral. For precision measurements of the amount of leakage present in refrigeration elements. This device was developed for use in refrigeration repair work. A standard vacuum gauge with an electrical visual meter is attached to a meter reader circuit in which an audio amplifier is used to drive a small speaker. This unit is then linked to a high precision potentiometer with a braille calibrated scale. Designed specifically for refrigeration repair work. Availability Schematics are available from the RERC office. Further information on this device is in the Spring 1981 issue of the Smith-Kettlewell Technical File, which is also available from the RERC. User Comments "This gauge has been very reliable and has extreme sensitivity to pressure change ... nice compact size." T.W., Refrigeration Technician, Covina, CA Simplifies access by a blind user to the computer screen. The SKERF-Pad is a computer access system which provides the blind user with a replica of the computer screen which can be addressed by touch. When a point is pressed, the user gets audible information about that position on the screen. The touchable screen is an 8-1/2" x 11" panel fitted with a tactile overlay which shows the locations of the lines on the computer screen. In addition, there are boxed areas which represent control functions of the screen-reading system. Managed by screen-reading software, the SKERF-Pad is used in conjunction with commercial speech synthesizers. In operation, the user selects a mode of presentation by touching one of the control areas on the pad. The system will present either speech or tones to indicate or identify individual characters, or whole words or lines. It can read whichever word or line is touched, or the coordinates of finger position can be stated. The idea is to present the blind computer user with a facsimile of the computer screen; this is sometimes more desirable than controlling the computer access system by nests of menus and layers of keyboard commands. The SKERF-Pad System was developed to provide a simple screen access tool which did not require memorization of keyboard commands for screen navigation and system control. Availability The original SKERF-Pad System was commercialized by Love Electronics, Goldendale, WA. Subsequently, a derivative access system, the "Master Touch," has become commercially available from HumanWare, Inc., 6245 King Road, Loomis, CA 95650, telephone 916-652-7253 or 1-800-722-3393, fax 916-652-7296. Facilitate locating connections and applying correct amounts of solder with a hot iron in crowded soldering areas. Suggestions from two readers of the Smith-Kettlewell Technical File led to designs of two guides for soldering: the English Solder Guide and the Japanese Solder Guide are credited to the late Frank Jeanmonod of Middlesex, England, and Mike Bhagwandas of Kobe, Japan. The former is a "darning needle" whose tip is wrapped with the desired amount of solder, and after this preparation, it is placed on the connection where its length can be used to guide the iron to the proper solder point. The Japanese guide is made of thin-walled stainless-steel tubing (hypodermic tubing); solder is fed through the tubing to the work, where it is protected from the iron, which is slid down the outside to the connection point. Often, when installing new parts, extra lead length serves as adequate guidance for the blind technician to find the proper connection points. However, in removing old pieces from equipment, or in cases where extra lead length is not provided on new parts, a guide which permits sliding a hot iron into place can be very useful. (Quick-heating irons, which can be put in place when they are cool, are not always the solution; the time taken for them to cool down to a temperature at which they can be touched again means that a series of connections would take an inordinate amount of time.) These two guides have their advantages and disadvantages: The tubular guide is prone to clogging (mostly avoided by careful manipulation). The darning-needle guide cannot clog, but it does not prevent occasional spillage of solder as the tubular guide does. Like all tools, these are subject to user preference. Availability Fabrication of these guides is easily done by individuals. Documentation is available from the RERC office for making and using both guides. A soldering iron which can be placed on the work while it is cool, then energized by the press of a foot pedal. First conceived by a newly blinded technician, Mr. Bernie Vinther of Kennewick, Washington, the tip of a battery-powered soldering iron was powered from a transformer and controlled from a foot switch. This configuration was published in the Smith-Kettlewell Technical File as the "Vinther Finger-Tip Soldering Iron." However, as with all "quick-heating" soldering irons, the temperature of the instrument can easily reach unpredictable extremes; the unit's ability to heat up quickly is a trade-off with its inability to dissipate heat in a steady-state condition. Thus, an electronic temperature controller was designed that prolongs life of the rather expensive tips of this device, as well as preventing wide variation of soldering temperatures reached for connection points of varying "heat capacity." As described in "Soldering, Part I" of the Smith-Kettlewell Technical File, Volume 1, No. 1, quick-heat, fast-cooling soldering irons and guns have long been favorites of blind workers in electronics. There are three disadvantages with commercial products in this class: * They are heavy. Those powered from the mains contain heavy transformers, and "cordless irons" have a battery in the handle that makes them heavy as well. * They are energized by a switch in the handle. They require tension of a thumb or finger to turn them on. This tension destabilizes the wrist and hand. * Battery-powered "cordless irons" have a limited capacity, thus limiting the types and number of connections they can be relied on to make. Mr. Vinther first tried powering a soldering tip of a "cordless iron" from a transformer under foot control. In this service, the tips ($7 each) were short-lived, due to extreme temperatures that damaged their ceramic insulators and/or heating elements. We designed a Wheatstone-bridge system, monitoring the resistance of the soldering tip, with which its temperature could be controlled, and even set for optimum use for a series of like operations. The result is a very lightweight heating element that affords rapid heating, but prevents overheating, of work pieces being soldered. The foot-pedal control means that the user's hand is stable when the soldering iron is in place. Its main disadvantage is the cooling time; after one connection is made, the tip must be left to cool for at least one minute before the tip can be touched to place it on another. Availability Documentation is available from the RERC office, and finished units are available from the Rehabilitation Engineering Service at cost. A means of making adaptations to a wide variety of devices and instruments on a custom/small-market basis. The availability of inexpensive development systems for small microcontrollers has made it practical to use single-board computers to adapt or create a wide variety of equipment for blind users. Several devices listed elsewhere in this compendium are examples of such adaptations. These examples, however, should not be seen as defining the limitations of this process, but as indicating its flexibility. Using the speech recording technology discussed above, and/or recently developed speech recording integrated circuits, and using microcontrollers and circuit boards costing from $20 to perhaps $150, it is often practical to adapt or duplicate instruments which provide output in speech, Morse code, variable tones, or vibrating tactors, all of which can be of great assistance in many vocational situations. The wide variety of relatively inexpensive technology available also means that it is less often necessary to make these devices dependent upon proprietary chips which may become unavailable should future duplication of devices be desired. The techniques and technologies used in the development of this concept are applicable in almost any situation where the information to be made accessible can be converted to electrical signals. In some cases, this means gaining access to display information from already existing instruments or devices. In many other cases, it means duplicating the sensors or other devices which are used in existing visual display devices and making the information from such sensors accessible. The major advantages to this concept are flexibility and cost of development. Almost any information which can be converted into meaningful electrical signals can be made accessible by nonvisual means. As more and more devices of this type are developed, the adaptation of new devices will be made easier as components of previously developed solutions can often be combined to produce new solutions. Availability Although not presently commercially available, this technology is included here to demonstrate the type of adaptive equipment which can be and has been developed to solve specialized rehabilitation problems. Persons interested in finding solutions to similar problems may contact the RERC lab for technical advice and/or referral.
SECTION I. VOCATIONAL TECHNOLOGY
CONTENTS
Auditory Data Flow Indicator ("Tweedle Dump"')
Auditory Oscilloscope
Vibratory Hearing Aid Battery Tester
Auditory Carpenter's Rule ("Rooller")
Stud Finder
FM Radio Station Operation
Knitting Machine Counter
Auditory VU Meter
Talk-&-Tones Multimeter
Thermo-Couple High-Vacuum Gauge
Temperature-Controlled Fingertip Soldering Iron
Talking Instruments Using Single-Board Computers
AUDITORY BREAKOUT BOX
AUDITORY DATA-FLOW INDICATOR
(The "Tweedle-Dump")AUDITORY OSCILLOSCOPE
AUDITORY BATTERY TESTER
VIBRATORY HEARING-AID BATTERY TESTER
SMITH-KETTLEWELL AUDIBLE CARPENTER'S LEVEL
AUDITORY CARPENTER'S RULE ("ROOLLER")
STUD FINDER
SMITH-KETTLEWELL DIGITIZED SPEECH TECHNOLOGY
FM RADIO STATION OPERATION
KNITTING MACHINE COUNTER
TAPE HEAD ALIGNMENT SYSTEM
TAPE INDEXER
AUDIBLE METER READER
AUDITORY VU METER
TALK-&-TONES MULTIMETER
ELECTRONIC DIAL MICROMETER
MECHANICAL MICROMETER
RECEPTIONIST'S MAT
TALKING REFRIGERATION PRESSURE GAUGE
2. Low pressure/vacuum ranging from -15 p.s.i. to 100+ p.s.i.
3. The machine is connected to a modified external refrigerant scale which allows an operator to precisely weigh the amount of Freon being introduced into a system as it is re-filled and tested.THERMO COUPLE HIGH-VACUUM GAUGE
SKERF-PAD SCREEN ACCESS SYSTEM
SOLDER GUIDES
TEMPERATURE-CONTROLLED FINGERTIP SOLDERING IRON
TALKING INSTRUMENTS USING SINGLE-BOARD COMPUTERS