# Amplifier current consumption

#### DrNick

Joined Dec 13, 2006
110
How would one calculate the DC current consumption of a 4 resistor biased BJT amplifier? Would it just be:
Itotal = Ic + Ib1; Ib1 = current through base resistor connected to Vcc? Or is there more to it than that?

#### hgmjr

Joined Jan 28, 2005
9,027
In such an amplifier the contributors to the overall current would be:

- The base bias network.
- The base current itself.
- The collector current.

hgmjr

#### fanie

Joined Jan 20, 2007
63
Not sure how your component is used, or how the resistors are interconnected to what, but total current would be all the elements currents added together.

To work out if your component will handle the POWER you require you have to use the V drop over the transistor, multiplied with max current through the Collector and that would give you dissipated watts. (Te-he - otherwise known as a heatsink). So if the drop is 5V at 3A = 15W to the nearest lamp pole. Biasing currents etc is usually small and needs not be considered unless it was your intent specifically. Sorry.

Just a friendly note, one usually talk about current flow or current drawn, and of power consumption, power is consumed (absorbed) when current flows.