Electronic components

	Resistor : unit = Ohm A resistor serves to determine what current intensity circulates in a place of the electronic circuit . It can serve, according to the formula U =R x I , to determine what tension there will be to its extremities . Values vary from almost zero ohm to several millions of ohms ( mega ) . The using limit is the power ( in watts ) that the resistor can support .
	Capacitor : unit = Farad A capacitor allows passage of the alternative current but not the direct current . It can serve to decrease or increase some frequencies of alternatives signals ( filters ) . Electolytic capacitors ( to the right ) have a connection’s direction . The negative extremity is indicated . They have also a great capacity , that allows them to store a quantity of electricity . Values vary from some picofarads to several thousands of microfarads . The using limit is the voltage ( in volts ) that the capacitor can support .
	Diode : A diode alows passage of electric current only in a direction . It serves mainly to straighten an alternative current to transform it into direct current . The current circulates between the extremity without ring to that witch as one ( according to the arrow of the symbol ) . If four diodes are associate in an alone cast block , we call it a bridge ( connectors ~ ~ + and - ) . The using limit is the intensity ( in amperes ) that the diode can support .
	Transistor : A transistor serves mainly to amplify electric signals . It can equally serve as switch for example to control a relay . There are two types of transistor : NPN and PNP according to the direction passage of the current . There are three connectors : the base control the current that circulates between the collector and the emitter ( E : arrow on the symbol ) . Transistors have different gain and power according to the model and often the size . There are components that have the format of a transistor but can be: regulator, triac, double diode . The using limits are the intensity ( in amperes ) or the power ( in watts ) that the transistor can support .