Richard, you might want to also contact via e-mail one or two of the people in the U.S. that are servicing Optacons for more specific on the spects for proper calibration. One person I'm familiar with is Richard Oehm and he occasionally checks this list. -----Original Message----- From: optacon-l-bounce@xxxxxxxxxxxxx [mailto:optacon-l-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Vickery Sent: Sunday, November 29, 2009 8:00 PM To: optacon-l@xxxxxxxxxxxxx Subject: [optacon-l] Re: Request for some advice Thanks everyone for your replies. The trouble hinges not surprisingly on the age of the Optacon. We have no manuals for ours other than a training manual, and so obtaining the design parameters for pin performance is a bit tricky. We obtained some circuit diagrams from Nigel Herring and from a search of the web. We are building a device to control the force with which the finger contacts the Optacon, and we of course will calibrate the set-up and then set values based on individual subjects' performance. I was surprised by how much small variations in contact force affected pin movement. These variations should not markedly affect your reading performance as you are using a dynamic stimulus and are well used to the device. However they make our life a lot harder, and I was hoping to reassure myself that this was normal performance for the Optacon. Thanks for your thoughts, Richard Vickery Nick Dotson wrote: > For one thing, lighter is better is the use of touch especially in this > device where one isn't supposed to hold the camera still, but it is intended > that the camera be moves and a person feels letters scrolling underneath the > finger identifying character combinations and patterns. Also, what you are > describing may be a tactile illusion. (grin) Pressing more firmly degrades > the efficacy of the finger's receptors, so it might seem that one is feeling > more on the sides than with the skin of the finger touching the bottom of > the trough of receptors. There are an intensity control and threshold > control the former providing the modification of the intensity of the > vibration of the reeds in the array. A tool used outside the context in > which it was intended will often give exotic results. But a tool intended > for research should be tuned up if only to make sure it is indeed > functioning within it's design parameters (calibration). It may be > beneficial to check out parameters of the device in maintenance, and other > manuals for data beyond slippery anecdotal perceptions of what the device is > or is not supposed to act like, as those of us using older or less > frequently serviced devices may have come to accept and even cherish the > idiosyncratic behaviors of our own beloved instrument for reading > independence. (smile) Finally, no two arrays felt exactly alike because of > the variations in reeds, and effects of the use of human assembly and > non-instrument based QA procedures among other things. > > W. Nick Dotson -- Dr Richard Vickery School of Medical Sciences, UNSW, Australia, 2052 ph. 61 2 93851676, fax 61 2 93851059 to view the list archives, go to: www.freelists.org/archives/optacon-l To unsubscribe at any time, just send a message to: optacon-l-request@xxxxxxxxxxxxx with the word "unsubscribe" (without the quotes) in the message subject. Tell your friends about the list. They can subscribe by sending a message to: optacon-l-request@xxxxxxxxxxxxx with the word "subscribe" (without the quotes) in the message subject. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.709 / Virus Database: 270.14.87/2535 - Release Date: 11/29/09 09:31:00 to view the list archives, go to: www.freelists.org/archives/optacon-l To unsubscribe at any time, just send a message to: optacon-l-request@xxxxxxxxxxxxx with the word "unsubscribe" (without the quotes) in the message subject. Tell your friends about the list. They can subscribe by sending a message to: optacon-l-request@xxxxxxxxxxxxx with the word "subscribe" (without the quotes) in the message subject.