Brown: Team Resistance/14 July 2008

14 July 2008

Back to lab after meeting → worked with Labview and Maex to fix apparatus

Dan came to the lab around 6pm to help me with the system

• Got voltage output to work with Maex
• Test reading resistance of a resistor with the circuit
• Voltage(input)<voltage(output) which makes sense because current goes through 2 resistors
• After it works with Maex, we switched to Labview

Diagrams of circuits on pg __ of my (Rima’s) notebook

Daniel Ludwig came to lab *helped me set up amplifier with power source

Diagrams of the AD524 (CD amp chip) and circuit set-up on power supply on page__ of my (Rima’s) notebook

Daniel drew simple diagram of our two resistors in series on page __ of my (Rima’s) notebook

Equations that set parameters of our system:

i=V/(R1+R2)

V1= iR1

V2= iR2

V(input)=V(R1/[R1+R2])

With R1 being the comparison resistor and R2 being the solution of cells (or whatever is being measured)

Our test: R1= 9.91kΩ R2= 477.7kΩ

V(input)= 1.02V

Saved as “test” under Team resistance documents

Initially, the circuit was wired under the consideration that it was under the property RSE (reference single ended) because the circuit was wired to a single ground

However, Maex keeps switching to Differential, so Dan helped me re-wire the system according to differential To do this we wired each input with the respective input ground across from it (0→8, 1→9, 2→10, as described in meeting with Professor Daniels)

Labview program

• because the voltage out is amplified, program divides the voltage input by the same degree to give the correct resistance
• created dial so that when the amplification on the CD amp chip is switched, we can switch the amount that the voltage input is divided by

To potentially reduce noise (fluctuations)

• use low pass filter
• braid wires→ to avoid confusion, use different colored wires
• take the mean of several readings and then take the mean of means

Apparatus is now ready for testing

Made 2 pVJ4 cultures for dilutions tomorrow

Incubate 8:20pm