Electronics Engineering

How do you reduce power consumption of a Wheatstone Bridge without changing the bridge resistances?

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December 01, 2007 4:20PM

It seems to me that there are two methods. Reduce the supply voltage to the bridge, or reduce the time that the supply voltage is connected (you could also apply both methods simultaneously). Which is best depends on the details of the application. 1. Reducing the supply voltage: The power consumption of the bridge will be proportional to the square of the supply voltage so halving the voltage will quarter the power consumption. It will also halve the voltage at the detector for any given imbalance so, to maintain the same resolution, the sensitivity of the detector needs to be increased by the same factor as the voltage. Clearly there are limits to this as the imbalance signal will eventually be lost in noise. 2. Reducing the time the supply is connected: It is possible to pulse the supply voltage and the power consumption will be reduced in proportion to the duty factor. Clearly the detector must be fast enough to take a reading during the time that the supply is connected. This might be done using a microcontroller - an output controlling the supply to the bridge and an A/D input to measure the imbalance signal.