What is Capacitor ?

The capacitor's function is to store electricity, or electrical energy.
The capacitor also functions as a filter, passing alternating current (AC), and blocking direct current (DC).
It has two legs, made of two semi conductor each other is called capacitor

There are many types of capacitor but they can be split into two groups, polarized and unpolarised.

Polarized capacitors (large values, 1µF +)

• Electrolytic Capacitors


• Electrolytic capacitors are polarized and they must be connected the correct way round, at least one of their leads will be marked + or -.
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Unpolarised capacitors (small values, up to 1µF)

• Small value capacitors are unpolarised and may be connected either way round. They are not damaged by heat when soldering, except for one unusual type. They have high voltage ratings of at least 50V, usually 250V or so. It can be difficult to find the values of these small capacitors because there are many types of them and several different labelling systems!



• Many small value capacitors have their value printed but without a multiplier, so you need to use experience to work out what the multiplier should be!



• For example 0.1 means 0.1µF = 100nF.

Variable capacitors

• Variable capacitors are mostly used in radio tuning circuits and they are sometimes called 'tuning capacitors'. They have very small capacitance values, typically between 100pF and 500pF (100pF = 0.0001µF). The type illustrated usually has trimmers built in (for making small adjustments - see below) as well as the main variable capacitor.



• Many variable capacitors have very short spindles which are not suitable for the standard knobs used for variable resistors and rotary switches. It would be wise to check that a suitable knob is available before ordering a variable capacitor