Various output options and autoranging
make the IMF-600 an attractive choice for many impedance measurement
and process requirements.
A perfect bench companion to your DMM,
the IMF-600A is a cost effective manual or
autoranging digital impedance meter that
complements the basic DMM to complete
your test and measurement needs. With its
low resistance measurement capacity and
Kelvin leads, the IMF-600A is invaluable for
locating PC board shorts.
A number of attractive features make it a versatile device. A companion limits comparator,
Model LC-603, allows selection for all functions,
on a GO/NO GO basis for inspection,
sorting, quality control, component selection,
etc...
Automatic measurement for all functions
is provided automatically with a 3½ digit display.
No balancing or manual operations are
required.
Analog & digital outputs may be used to
interface to comparators or other devices.
4-Wire shielded Kelvin test terminals - short
circuit location ensures precision measurements even for very low impedances like contact
or wire resistance and makes locating PC
board short circuits an easy task.
Principle of Operation
The impedance Zx of an unknown component
X is defined as:
Zx=Vx /Ix
where Vx is the voltage across the unknown and Ix is
the current through the unknown. The IMF-600A implements this
computation as shown conceptually in the figure.
A sine wave
generator drives current Ix through unknown Zx
and the standard resistor Rs in series with it. Two
ac coupled differential amplifiers measure the
voltages Vx and Vr across the unknown and the
resistor respectively. The impedance Zx is then
computed as follows:
Zx=Vx /Ix
Zx=RsVx /Vs
Except for pure resistance and conductance, Zx is a
complex ratio with real and imaginary components
which are then computed. The voltage
being measured, e.g. Vx is broken down
into the "in phase or 0°" and the "quadrature
or 90°" components with respect
to the test signal. These are used to
provide the real and imaginary portions
of the complex impedance. A pure resistance, for example, will produce only
an "in phase" component, whereas
an ideal capacitor will result in only a
"quadrature" signal. |