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Message ID: 643     Entry time: Sun Jun 23 14:39:28 2013
Author: Giorgos Mamakoukas 
Type: DailyProgress 
Category: SUS 
Subject: Finished 6 PCB Boards 

On Friday, we tried to get zero offset for the voltage output of the strain gauge, by replacing our fixed-value R2 resistors with adjustable ones. At R2=22.74kΩ, we achieved a 0.01mV offset, which we would then correct with our DC motors.

We measured the voltage required to drive our motors at a slow, steady pace; 5V seemed sufficient. To get that voltage, we used the voltage divider method. The internal resistance of the motors were roughly 100Ω, so we added a 500Ω resistor in series to get close to our desired Vout, using our 15V source. Our motors were "broken" and would however move at all times once connected and pause only when the control buttons were pressed; we ordered new ones.

Since we successfully built one circuit for one strain gauge and DC motor, we wired the rest 5 PCB boards. At the end of the day, we were happy to look at the following:


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