13
Rev. 2 – 10
th
November2015
A typical problem related to the fan speed is the resistances selection.
Here in the following a simple procedure for calculating them.
1) Find the
Voltage
(Required)
= V
Req
for achieving the
Speed
(Desired)
using the diagram
Signal/Speed of figure 14.
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!
"#$
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2) Reminding that ./01/2345./
6
7
8
7
9
%:;<=2
And that the analog
Input Impedance =
Z
in
=
20kOhm
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9
./
6
:;7
9
!7
9
9
7
9
./
6
&
'
!:;
>
?
:;!&
'
./
6
@
9
A;&
*'
9
./
6
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In figure 15 is shown the behavior of the analog voltage signal increasing the potentiometer value.
Fig.15 – Effect of the potentiometer value on the analog signal
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