Transistors

mstechca

New Member

• Apr 23, 2003

• #1

When I buy BJT transistors from the store, the price label contains the following: amps, voltage, and polarity (NPN or PNP).

The transistors I buy are marked 100ma and 500ma.

Does this mean that the marked amp value is the minimum value required to turn it on?

 

kinjalgp

Active Member

• Apr 23, 2003

• #2

No, that is the maximum current that it can handle. In other words, it is the maximum value of collector current for which the transistor operates safely. Beyond that it will go into "thermal run-away".

 

Phasor

Member

• Apr 24, 2003

• #3

Also - the voltage is the maximum collector-emitter voltage. If you exceed that, it can fry

 

windozeuser

Member

• Nov 24, 2003

• #4

AHHHHHHHHHHHHHHHHHHHHHHHHHHH! THE OLD TRANSISTOR BARN FIRE :shock:

 

Optikon

New Member

• Nov 25, 2003

• #5

kinjalgp said:

No, that is the maximum current that it can handle. In other words, it is the maximum value of collector current for which the transistor operates safely. Beyond that it will go into "thermal run-away".

Click to expand...

Just to be clear, this is not necessarily so. Thermal runaway is a power dissipation related problem. I can find an operating point such that the collector current is less than the maximum rated and still cause thermal runaway.

 

kinjalgp

Active Member

• Nov 25, 2003

• #6

Yes that is also possible.