Download The Linear Variable Capacitor and Its Characteristics

The Linear Variable Capacitor and Its Characteristics
The capacitor can change its capacitance unit linearly with our effect. This capacitor
consist of a spring which on fixed plate, iron slug which connect to spring and moveable, and
brass sleeve which is fixed too. When the iron slug changes its position, the capacitance will
be change. And the sleeve fitted around the coil.
The capacitance magnitude depends on the length of the iron slugs position. If the
length which is slugs length in the sleeve increase, capacitance will be increase. Therefore
we can change the capacitance what we need.
Our experiment shows that the capacitance changing to be linearly. So when we do
this experiment firstly we connect to what we need the connection our circuit. We look at
our datasheet which is called Figure 3, and start to do connection. Our variable capaticance
have input which connect to 40kHz oscillator and have output which connected A.C
Amplifier. We set the amplifiers gain to 1000 and then we connect the 40kHz filter with
amplifiers output. After, the full wave rectifier unit we connected to filters output in
addition we connect to voltmeter whose other connection to zero the F.W. rectifiers output.
In this way we complete the our circuit.
After we finished the all connections, we start doing experiment regularly. We want
to change our capaticance so our voltage will change and we understand that our
capacitance were be changed. We measured the irons zero positions voltage and we turn
the iron slug 1 round. And each one turn counter clockwise we reduce our output which
shown as Table 1.
After we obtain the table we want to see how the values decrease linearly or not. we
can learn this when we graph our values using MATLAB as shown in Figure 1.
Figure 1
In the last part of documentation I will tell what kind of capacitor there are and
where we use this capacitor. Fistly there are two kind of this capacitor, mechanically
controlled and electronically controlled. We can change with our hand in the mechanically
one and small operations can be done. But they are chipper than electronically one. And the
mechanically controlled capacitors have many different kind such as butterfly, multiple
sections, spilit stator. The electronically one is the more advanced one because we can
controlled very small units. In addition the digitally one using all of the life. There are many
using area such as microphones, switches, industrial sensors.
Engin KAYA
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