Finding total circuit current consumption for BJT amp

AI Thread Summary
To measure the total power consumed by a common base BJT amplifier, one should measure the voltage from Rc to Re and the current from Vcc to Rc, then multiply these values. The circuit configuration and biasing can affect the measurements. A practical method for measuring current consumption is to use a small sense resistor in the power supply connection, ensuring the resistor's value minimizes IR drop. This approach allows for accurate current calculations using Ohm's law. Proper measurement techniques are essential for assessing circuit performance effectively.
Physicist3
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For a common base bjt amp, would I be correct in thinking that to measure total power consumed by the circuit, you would measure voltage from Rc down to Re (inclusive) and take a current measurement from between Vcc and Rc and then multiply together?
 
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Physicist3 said:
For a common base bjt amp, would I be correct in thinking that to measure total power consumed by the circuit, you would measure voltage from Rc down to Re (inclusive) and take a current measurement from between Vcc and Rc and then multiply together?

It may depend on how you draw the circuit, and how you bias it. In this configuration below, the current consumption from the power supply should be pretty apparent:

http://autonopedia.org/wp-content/uploads/crafts-and-technology/electronics/Common_base.png

http://autonopedia.org/wp-content/uploads/crafts-and-technology/electronics/Common_base.png
 
The easiest way to measure it is to put a small sense resistor in the power supply connection (where small here means small enough to make the IR drop not an issue). Then you can calculate the current consumption from Ohm's law.
 
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