Physitemp Instruments BAT-12 - Manual (Page 8)

and almost instant response of the probe. Fluctuations can easily be eliminated by
bringing the probe into contact with a metallic object, thus increasing its effective
mass and slowing the response. Using a larger probe will have the same results.
6.10 Measurements on Solid Surfaces. These are most easily made with surface
probes such as our BT-1 and MT-D. The right-
angled tip provides the 10 diameters of probe
contact specified in Section 6.6. Straight probes
may also be used, provided that sufficient shaft
length is in contact with the surface to be meas-
ured. In general, the smaller the probe, the more
accurately it will measure the surface temperature of a solid. For instance, an MT-
29 microprobe, because of its small size, needs to be in contact with the surface for
as little as 1/8”. SST-1 has a 1/4” gold disc sensor. Gold is an excellent conductor,
and is non-allergenic and non-polluting. It makes a fine skin surface probe.
6.11 Measurements in Electronics. BAT-12 and ICT-4 provide the quickest and
cheapest method of getting accurate reading on both discreet components and inte-
grated circuits used in electronic equipment. ICT-4 has two important differences
from the regular MT-4 probe. There is a 5 1/2” handle suitable for use in the hand or
in a micromanipulator and the micro-thermocouple protrudes slightly beyond the
steel sheath and has some thermal isolation from it. This probe was designed for use
on areas of 5-100 microns in diameter and is used perpendicular to the surface to be
measured. The heat loss described in 6.3 occurs and temperature readings are slight-
ly low -- normally about 0.5°C low. Each probe can be readily calibrated on a larg-
er surface. First lay it parallel to the surface and note the reading. Then take a read-
ing with it perpendicular to the surface; note the difference. Add this difference to
the subsequent reading when using the perpendicular position.
6.12 BAT-12 with a suitable probe has the ability to measure surface gradients,
giving almost instant readings at each point. This feature enables heat sinks to be
designed without guesswork, for maximum efficiency with minimum metal. It is
equally easy to check the adequacy of thermal bonding between a power transistor
or rectifier and its heat sink. General purpose probe BT-1 is suitable for this and
many other measurements. When probes such as BT-1 and the larger HT-1 and HT-2
are used for surface measurements, speed of response and accuracy can often be
improved by use of a heat conductive material such as ‘thermal grease’ or silicone
grease applied between the probe and surface. Note: BT-1, HT-1 and HT-2 should
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