Triggering From Magnetic Transducer Mm 0002 - BRUEL & KJAER 4912 Instruction Manual

Detailed information on how to apply the Probe is given in the Product Data · sheet de-
scribing the MM 0012 . It should be fixed at a distance of about 1 mm from the moving
surface for best results, though it can be used at a greater distance, especially if it is as-
sisted by an auxiliary light source such as a hand torch powered by a battery (not
mains). The surface should have fixed to it a contrasting mark (light on dark, dark on
light) whose passage through the beam causes triggering. The lamp will flash in syn-
chronism with the dark-to-light transition. The dimensions of the MM 0012 are shown
in Fig.3.3, and examples of fixing arrangements in Figs.3.4 and 3.5.
3.4.3. Triggering from Magnetic Transducer MM 0002
The Magnetic Transducer MM 0002 (Fig .2, Chapter 1) is a variable-reluctance device
with a built-in permanent magnet . Changes in the reluctance of its magnetic circuit, part
of which is external to the Transducer, cause a voltage at its terminals . This voltage can
be made sufficient to trigger the 491 2.
If the moving object to be studied with the Stroboscope is ferromagnetic, it is sufficient
to mount the Transducer so that the object passes as closely as possible- 1 or 2 millime-
tres to the Transducer at its active end. The dimensions of the MM 0002 are given in
Fig.3.6. If the moving object is not ferromagnetic, or the motion is continuous rather
- - - -- - do
0.3
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Fig.3. 6. Dimensions of Magnetic Transducer MM 0002
Fig.3.
7 .
MM 0002 Magnetic Transducer in use
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