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User Name Thread Name Subject Posted
GUEST,Mikey joe Tuner for a blind musician (13) RE: Tuner for a blind musician 02 Feb 03


Barry A. Romich Prentke Romich Company Wooster, OH


As a result of severe visual impairment a professional singer and songwriter, well known in RESNA circles, was unable to see the LED indicators on an electronic guitar tuner. A simple circuit was designed to be built into the tuner to monitor the LED drive circuits and generate a corresponding audible indication in an earphone. The implementation was successful and, with appropriate modifications, should be generalizable to other items using LED or incandescent lamp indicators. A circuit diagram is available.


People with severe visual impairments generally find it either difficult or impossible to use common items that utilize visual indicators. In this case, a professional singer and songwriter who is legally blind wanted to make use of a small handheld portable battery powered electronic guitar tuner 1. This is an especially valuable device in particular situations, such as when tuning in a noisy environment. The tuner has LEDs to indicate the string being tuned (one of six) and whether the tone is FLAT, SHARP, or IN TUNE. If no note is detected, then none of the tuning LEDs are lighted.


The singer was able to tune each string to the general desired tone, and thus did not need to have an alternative indication of the notes. However, he did want to have an alternative indication of the FLAT, SHARP, and IN TUNE LEDs.


A system was proposed to the singer in which he would use an earphone to listen for audible indications of the tuning LEDs. Each LED would produce a different tone in the earphone. The IN TUNE LED would produce a pleasant middle C range tone. The FLAT and SHARP LEDs would produce correspondingly lower and higher tones. The singer agreed to proceeding with a prototype design.

In addition to the basic function, design criteria included ease of use, construction inside the enclosure, low battery drain, low cost, and ease of replication.


The tuner was opened and the power and LED drive circuits were traced. The unit was powered by a nine volt battery with a five volt regulator supplying power to the digital circuits. It was proposed that the tone generating circuit be powered at the five volt level in order to take advantage of the system for powering up and back down, which happens automatically after a preset time.

The three subject tuning LEDs were driven by low true circuits. Of course, only one would be on at a time and with no note being detected all three would be off. A common CMOS low power timer circuit was selected to implement the function.


Even though the tuner was small, the enclosure had ample open internal space. The "freespace" circuit was attached to the tuner circuit board and wired to the power and LED drive circuits. An earphone jack was added. In addition to the three tones, a very low frequency ticking is a reminder that the power is still on when no tone is being detected.


The completed unit was evaluated by the singer. He has commented repeatedly that, for the first time since losing his sight, he has the pleasure of playing a virtually perfectly tuned instrument. He refers to the solution as elegant in that it provides the desired function with essentially no additional demands on him or other adverse effects.


The manufacturer of the tuner was contacted and an agent indicated that they receive occasional requests for modifications of this nature. The design is being shared with them.

With appropriate modifications, the design should be able to be implemented on other devices that use LED indicators.

A circuit diagram is available by contacting the author.

1. Model PIK-700 Sabine Musical Manufacturing Co., Inc. 4637 N.W. 6th St. Gainesville, FL 32609 Tel: 904-371-3829

Barry Romich, Prentke Romich Company ,1022 Heyl Road Wooster, OH 44691 Tel.: 216-262-1984 ext. 211 Fax: 216-263- 4829 e-mail:

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