my mood lamp design

Audioguru

Joined Dec 20, 2007
11,249
The collector current is not specified by the base current. The minimum collector current is specified to be 350mA when the base current is 500uA but your base current is higher and you do not know the actual amount of gain and what the actual collector current will be.

Without the collector resistor or with a lower value then you cannot limit the current to 350mA.

Why not use a logic-level Mosfet that saturates with 0.1V loss? Then if the LED is 3.5V, the power supply is 5.0V and the resistor is 4 ohms then the current will be exactly 350mA.
 
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