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Calculating base current?

MacIntoshCZ

Active Member
Hello,
I would like to know how can i calculate base current when base is directly connected to emittor/collector?
Ir1 = 600uA Ib= 2uA
Spice says...
I though current would be splitted in half. But it isnt.
thanks
1611067044719.png
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I'd expect it to be the collector current divided by the hFE at that current, as long as the overall current is within the transistor continuous rating.

eg. For an hFE of 200, base current 1/200th the collector current.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I suspect that while it's nice in theory, in reality it will be FAR different - when you operate transistors near saturation point the gain drops off considerably.

However, why would you want to know? - you're wiring the transistor as a diode - so there is no base and no collector.
 

audioguru

Well-Known Member
Most Helpful Member
With the base connected to the collector then the emitter current is exactly the same as the collector.
With the base connected to the emitter then the transistor is turned off and does not conduct any current.
 

audioguru

Well-Known Member
Most Helpful Member
My calculator also has many extra useless digits that I usually round off.
 

gophert

Well-Known Member
Most Helpful Member
Hm. So why do we all spend extra money for the digits to the right on our DVMs? E
That's why I usually use the 200v scale - so I don't see all those numbers flashing and moving in the 3rd, 4th and 5th decimal places at lower scales.

Like this one...
image.jpg
 
Last edited:

JimB

Super Moderator
Most Helpful Member
Hm. So why do we all spend extra money for the digits to the right on our DVMs? E
Most of the time the extra digits are not required, but occasionally when they are required the extra digits no longer seem expensive but priceless.

JimB
 

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