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 .