princestephenranji

Hi alivol, I tried to use transistor as a switch,also i dont know how to make a schematic picture.i just experimented with transistor,resistor and a relay. Hi indulis, You are currect,emitter current is high which is essential to switch on the relay,i want to know the theory behind this heating Thanks to everyone who replied & read my post.

i tried many transistors like sl 100,bc 548 etc in these the base is connected to voltage source through a high value resistor (some 1 kilo ohm) when i tried to decrease the value of resistor,output current to load decreased and transistor temperature increased.why transistor temperature increased & output current decreased when i decreased the value of resistor.

Why does a transistor heat when base current is high

Sorry physics sir,i am only a student also do not know much about transistor theory.But in practical use of transistor no one thinks of theory.I just used the term 'jump' just to explain its working for practical circuit designing,a simple example is switching a relay 'on' using npn transistor in conjunction with IC MCT2E.('+'ve voltage from IC MCT2E is feed to base of npn transistor and '-'ve voltage from emittor of npn get transferred to collector which then powers the relay).

A NPN transistor works on the basis of semiconductor theory ie current given to the emitter (N Region) is the sum of base current (P Region)+collector current(N Region).in power mode use of NPN transistor when the base gets +ve voltage(low current) -ve voltage from emitter jumps to collector.In amplifying mode signals feed in emiitor-base region jumps to collector-base region if we include a battery source in collector circuit we can get an amplified output.

Hi everyone,can anyone guide me in choosing a best btech(engineering) branch.In our location mainly four branches are there 1) Electronics & Communication 2) Applied Electronics & Instrumentation 3) Electronics & Instrumentation 4) Electrical & Electronics.My favourite hobby from my childhood is desigining,construction of electronic circuits and i love electronics so much,now i am confused with which branch to take,which branch in these deals with electronics more ? please help me.