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DiscoverCircuits.com, has
26,000+ electronic circuits or schematics
cross-referenced into 500+ categories. As a
vital resource for engineers, hobbyists, inventors &
consultants, the site's collection of information will
help you find quick solutions to electronic design
problems. |
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DiscoverCircuits.com
-- Hobby Corner
Last Updated on:
03/19/2008 06:54:11 AM |
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Battery Charging Current Indicator |
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Anyone who has ever had a shocking experience on an especially dry day
is acutely aware of the kinds of high voltage that can be generated from
a simple walk across a carpeted floor. Those same finger to metal sparks
can destroy or disrupt sensitive electronic circuits. Good design
practices take great care to avoid such potential disasters by
maintaining sufficient insulation between metal or plastic enclosure
parts and the electronics within or by shielding any especially
sensitive components. But, the only sure way to determine if such
measures have their desired effect is to test them. Many high quality
and certified electrostatic discharge instruments do exist which can
test your product for the worst possible static discharge. However, they
are expensive; to buy or to rent. But, you don't have to spend thousands
of dollars determining if your product is susceptible to high voltage
discharges. An inexpensive device that will work nearly as well as the
precision units can be found in nearly any hardware or department store.
Remember those piezoelectric propane gas grill lighters? You know, the
ones with a long metal neck that you stick next to the burners? Well,
with a very simple modification those spark ignites can generate some
15,000 volts, enough to determine if your product has a real problem or
not.
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Most of the units have a four prong triangle shaped metal piece that is
pressed over an insulated center electrode. When the igniter handle is
pressed sparks are generated across the electrode and the sharp prongs.
To modify a unit for use in static testing, first bend or cut off the
sharp prongs of the outer metal piece, preventing the sparks from
forming. Next, insert a stiff wire about 2 inches long into the center
electrode which usually has a soft conductive rubber center. That is all
there is to it. Since one side of the internal piezoelectric crystal
that generates the high voltage is connected to the handle you may wish
to connect a second wire to the metal body. Otherwise, touching the
chassis ground of the instrument is usually enough to complete the
circuit. |
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