freedom from the wire

[Robert Goodale]

ANNOUNCEMENT!

I have just successfully completed an invention that has plagued piano
technicians your years, (oh, I can just hear the applause already... ).

As an SAT II user I have shared the frustration with countless others on
dealing with the dreaded foot pedal.  Always dragging the tangled mess
out, untwisting it, then winding it back up, and so on.  Then every
couple of years the wire shorts out internally and you have to break out
out the soldering iron and replace it.  Have you had enough of the wire?

For some time now I've been thinking about how to eliminate the dreaded
wire-  a wireless remote switch if you will.  I began exhaustive
research on the subject over six months ago.  I chose not to discuss
this publicly until I had a working model.  I soon discovered that
building such a device is much more involved than I originally
conceived.  It sounds simple enough-- a single channel uni-directional
transmitter/receiver.  I sought out for companies that made such units.
Hours of web searches, phone calls and visits to local suppliers with
only marginal results.  Pre assembled remote modules are generally too
expensive and over the counter units are bulky and impractical largely
because they are built for commercial applications.  I even looked into
key chain remotes for auto alarms.  The transmitters are perfect-- very
small and cheep. The receivers, however, are integrated into other
systems and are very expensive.  The same story with remotes for garage
door openers and no one wants to sell you just the remote components-
and if they did again it would be too expensive.

The solution turned out to be relatively simple one although I did spend
considerable time experimenting and making the necessary modifications.
Having already done it now I imagine that I could build another one in
about a tenth the time.  The solution stems from your local Radio Shack
store- a wireless doorbell chime, (stock #63-874).  It costs only
$19.99.

You are required to remove the circuit boards from both the button unit
and the bell unit to install in a new chassis, (You could use the button
as it is if you want to get creative and find a way to attach it to your
tuning hammer but it is slightly bulky for that).   The ringer part of
the receiver must be disabled, (unless you want it to go "bong" overtime
you change notes).  I installed the transmitter inside a new small
chassis box, (available at any electronics supplier), along with a
heavy-duty switch that has a feel similar to the wired foot pedal.  I
also added a second on/off switch and an LED which lights up when the
unit is transmitting.  With the heavy switch and the battery the weight
of the unit is perfect.

The receiver is also installed in it's own compact chassis box. Some
significant analyzing of the circuit was required to trace the output of
the RF receiver before it goes to the ringer circuit.  Sure enough once
located, (off one end of a particular resistor), there is a clear and
simple on/off binary logic output.  From here I have a 6" cable leading
from the chassis box to plug into the SAT.  I again included an on/off
switch and an LED that lights up whenever the unit is receiving.  My
first intention was to install the receiver directly inside the SAT
unit.  There is in fact barely enough room for it to fit.  Unfortunately
my experimentation revealed that there is too much RF interference from
the CPU which prevents the receiver from working properly.  An RF shield
around the receiver would prevent this but at the same time it would
block off the signal from the transmitter.  Nevertheless the external
unit is relatively small and can be stuck on the outside with velcro.
It can then simply be removed for storage in your tool kit when you are
done.

both units feature a three channel encoder and I mounted the circuit
boards in a position so that the slide selector switch is accessible
through a slot in the side of the chassis box.  If you are tuning in a
customers home and discover that Ms. Jones' garage door is on the same
channel you can simply change the channel- POOF! problem solved.

I spent a considerable amount of money going through the trial and error
experimentation process but at this point knowing what I'm doing I could
probably build the system for around $45.00.

Well that's my show and tell for today.  Now more wires for this cowboy!



Rob Goodale, RPT
Las Vegas, NV