[access-uk] Modified Cherub guitar mate tuner for blind
- From: "Aedan O'Meara" <aedanomeara@xxxxxxxxx>
- To: <access-uk@xxxxxxxxxxxxx>
- Date: Mon, 19 Nov 2012 11:18:25 -0000
Hi all,
Would anyone have a contact who would make this as a project?
I have the instructions in pdf and software to make this.
Aedan.
www.lushprojects.com
Guitar Tuner for a Blind User - 2010
This is a project I did for a colleague at work. It's a modification of a
Cherub Guitar Mate WST-550G guitar tuner to provide an audible output to an
earpiece so a blind user can tune a guitar.
How it works
I chose to modify the Cherub tuner because it uses an LED display which I
thought would be easier to hack-into than the LCDs used by many of the new
tuners or the analog meters used by the older tuners.
Once I got the tuner I probed the L E D s and found that they had a common
positive line and individual negative lines that were controlled by a
dedicated chip in the tuner under the inevitable blob of plastic.
To make the modification I attached a second box to the back of the Cherub
tuner. In this box is an AVR ATMEGA 168 which provides the audible output. A
large hole was cut between the Cherub tuner and the new box and wires run
from each of the LEDS to the AVR. I also moved the battery to the new box to
create space to attach the boxes and run the wires.
As well as the two controls on the original tuner I also added a button
which selects which string the user wants to tune. If the tuner is showing
an output for a different string then no audio sound is produced. This
prevents rather confusing sequences of sounds that occur if you don't put
this check in.
The AVR software was written in C using WinAVR and is pretty simple - poll
the LEDs and then create a sound that matches the indication.
Modified Guitar Tuner
Attaching wires to the original circuit board
Inside the back box of the modified tuner
Usage Instructions
Note on directions: "Top" means the end opposite the clip. "Left" means
towards the side with the clip on. "Bottom" means the direction that the
clip sticks out when it is unfolded.
1) Unfold the clip from the bottom and clip it on to the head of the guitar.
Insert the earpiece so you can hear the tuner.
2) Select "natural" or "flat" tuning using the sliding switch on the side of
the front box. Towards the bottom is natural. Towards the top is flat.
3) Switch the device on by sliding the switch on the top of the front box to
the left. The tuner will play a short up-and-down scale to show it is
working. Seeing users will see the lights come on.
4) Select the string to tune using the button on the top of the back box.
Each press of the button will advance the string. The string selected is
indicated by playing a descending scale with the number of notes equal to
the string number. String 1 is the highest note on the guitar and string 6
is the lowest.
5) Pluck the string you are tuning gently. If the string is detected by the
tuner you will start to hear audio feedback on the tuning.
A high pulsing note means the string is too high. A low pulsing note means
the string is too low. For high and low notes the rate of pulsing indicates
how close the string is to the right tuning. The faster the pulsing the
closer the tuning. A middle note means it is tuned correctly. Adjust the
tension in the string based on the feedback.
The tuner may change its response a little so pluck the sting a few times
and listen to the response. When you fairly consistently get the middle note
back then the string is right.
6) If a few plucks of the string don't produce a response then the string is
probably too out of tune to be picked-up by the tuner. Keep plucking and
adjust the tension until you get a response.
7) Repeat for all strings
8) Once the guitar is tuned check all the strings again.
9) Switch off!
Want to Make One?
I made this as a favour for a friend and for a bit of interest. I am not
really able to make more.
I am making the circuit diagram and software available for anyone who wants
to build their own version. I will not be providing any other support for
builds though. This isn't a beginners project - parts of the build are
difficult and the documentation is sketchy!
Circuit Schematic and Build Notes
WinAVR Software Files
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