Author Options:

BJT (NPN TYPE IN COMMON EMITTER CONFIGURATION) current drawn between different ends of transistors Answered

Hello Everyone

While iam connecting a motor of ratings 3v ,300milli amps in the emitter side it is drawing around 200 amps ,whereas when iam connecting it in emitter leg it is drawing 200ma,but in collector leg it is taking 300mamps,

1kohm resistor is connected to base and 10ohm resistor to collector and supply voltage is 5v

but as per bjt emitter leg is the one which will draw more amps,then why this behaviour??


The forums are retiring in 2021 and are now closed for new topics and comments.

1 year ago

I suspect the "200 amps" should be "200 mAmps"...

with a NPN:
the collector is the pin where the BJT collects is mayority of current to output.
the base is where everything is based upon and what controlls the flow (Beta)
the emitter is where everyting is emitted (Current from base + current from collector)

(See Attachment)
Basically and simplyified:
IE = IB + IC
IC = IB * beta

beta = Factor IB is amplified and drawn as IC.
beta is very often also reffered to as hFE

Lets take a classical BC547 BJT:
hFE of somewhere betwheen 110 to 800.
So: If you push 1mA into the base, the BC547 will try to pull 110 to 800mA from the Collector. Both currents will then be pushed out to the emitter and result in something from 111mA to 801mA.

Now you may undestand the very baseic and simplified function of a BJT.

Now to your question: I dont really understand where you connect what.
Please post schematics (Can be hand-drawn) where we can see the source with its connection to the BJT, the load with its connections to the BJT and the parts on the base-pin.