Audible Guitar Tuner
Romich, Barry (1996). Audible indicator for guitar tuner. In Proceedings of the 1996 RESNA Conference. RESNA Press. Arlington, VA. pp. 170-171.
AUDIBLE INDICATOR FOR GUITAR TUNER
Barry A. Romich
Prentke Romich Company
Wooster, OH
ABSTRACT
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.
BACKGROUND
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 ~. This is an especially valuable device in particular situations, such as when tuning in a noisy environment. The tuner has LEDs to indicate the siring 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.
STATEMENT OF THE PROBLEM
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.
RATIONALE
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.
DESIGN
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.
DEVELOPMENT
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.
EVALUATION
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.
DISCUSSION
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. (See below.)
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: 330-262-1984
Fax: 330-263-4829
Email: bar@prentrom.com
The author is willing to provide additional guidance to anyone wishing to fabicate this or a related circuit or wishing to purchase a guitar tuner that can be adapted in this way. The service of fabricating is available in exchange for a donation to the AAC Institute. Contact: bromich@aol.com.