Kellyco PULSE STAR II PRO, Инструкция по эксплуатации

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Trans mis si on Pha se
A strong duty cur rent is flow ing through the search coil about 600
times per sec ond.
The lin early in creas ing cur rent builds up a pri mary mag netic field which
ra di ates as shown in fig ure 1. The cur rent is abruptly cut off af ter a cer -
tain time, so that the pri mary mag netic field col lapses quickly caus ing
so-called eddy cur rents in the metal ob ject. The strength and du ra tion
of these eddy cur rents de pend on the elec tri cal con duc tiv ity, size and
shape of the ob ject.
Af ter a short time de lay the search coil is con nected to the re ceiver
input.
Re cei ving pha se
The de cay of the eddy cur rents in the ob ject pro duces a sec ond ary
mag netic field, which is ra di ated by the ob ject (fig ure 2). This sec ond -
ary mag netic field has its ef fect also on the coil and here in duces very
low volt ages, which are am pli fied and dis played by a me ter and an
audio sig nal.
Ob vi ously, the de tec tion range has phys i cal lim its, be cause these volt -
ages are ex tremely weak and can be ob scured by ex ter nal mag netic
fields.
In gen eral, the pos si ble de tec tion range will in crease quickly with in -
creas ing ob ject size. This is es pe cially true for the PI-prin ci ple. But the
elec tri cal con duc tiv ity and the shape of the ob ject are also im por tant
fac tors.
Re lated to this, fer ro mag netic met als take a spe cial po si tion. If these
met als are ex posed to the mag netic fields of a PI-de tec tor, they will be
mo men tarily mag ne tized. Al though the elec tri cal con duc tiv ity of these
met als is poor and, there fore, the de cay of the eddy cur rents is very
short, the strength and the slow de cay of the mag ne ti za tion causes a
strong sig nal. This is why PI-de tec tors are very sen si tive to even small
fer rous ob jects. The PULSE STAR II PRO of fers you the pos si bil ity of re -
duc ing the sen si tiv ity to these ob jects (some smaller fer rous ob jects
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2 Operating principle