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From software algorithms to material selection, Mr. Roboto strives to meet you
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In December, I got some very interesting questions that will take longer to answer than I
had time to deal with just before the holiday
season. Fear not! Mr. Roboto is on the hunt and
will return with answers to those particular
questions in future columns! However, some were
questions that I could answer with information I
had on hand, so we’ll discuss those.
Q. This question came in response to a project on my own website at www.techtoystoday.com/projects/
I’m attempting to design a simple and
inexpensive set of tactile feelers for our high
school robotics class. I liked your simple approach,
but have a question.
We’re using the simpler PICAXE processor but
the implementation would be comparable, to
running a wire to the PICAXE input pin, then
pulling the pin high when the switch is closed.
My question is have you had any problems
with shorting out the processor? My concern is
with the “whiskers” since contacts are bare wires
exposed to the environment. I’m concerned that
the students will inadvertently fry the processor
with static electricity or even something else.
A. You are correct. Without a little more additional circuitry, your microcontroller will be at risk from static electricity. Figures 1
and 2 show the front and back of the whisker
switch to which this question refers. It is dead
simple to construct and works really well, with
It takes a pretty strong soldering iron to solder
the piano wire (use small gauge “springy” wire) to
the copper plating of the generic, single-sided
un-etched PCB, but it works well if you are patient.
Figure 1. Whisker switch
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