SMD Test Tweezers
1. Introduction
From time to time I take apart components from PCB cards and put a lot of Surface Mount Devices in my junk box.
In order to test or measure these SMDs, at least the passive ones, I use my digital multimeter (for resistors) or my AADE LC IIB Meter
for capacitors and inductors. The main problem is to press the probe
tips firmly against the SMD without flipping it on the floor where it
is generally impossible to find it.
Furthermore I wanted a test
clip which can be used without pressing it against the SMD with fingers
during the measurement, in order to mitigate "fingers effect" errors,
especially for low-value capacitors.
2. Construction
I used a small alligator clip and 2 strips of
one side epoxy PCB (4 mm wide by 15 mm long).On each PCB strip, I
stripped off the copper except 4 mm at one end and 6 mm at the other
end.
Then I soldered the 6 mm copper end on each jaw of the
alligator clip and soldered a 150 mm wire to each end of the 4 mm
copper square.
The capacitance added by the wires and the tweezers
is a few pF and the LC IIB can make up for this small value without
trouble.
The pictures below show a simple drawing of the tweezers and the complete test clip with an SMD between the jaws.
3. Conclusion.
This test tool was built in less than an hour and its total cost is nearly zero!
Note
: when I need accurate measurement of small value capacitors, I hold
the alligator jaws opened with a piece of insulated material while
zeroing the LC IIB meter.
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