April 2013
I’m trying to use an SDX01G2 pressure sensor to log CPAP breathing patterns. The circuit uses an LM324N op-amp, an ADC0831 CCN eight-bit A/D converter, and a BASIC Stamp 2 processor. The problem is the sensitivity. The output goes from 0 up to 191, and then back to 0. I have tried several op-amp configurations with little success. I am a newbee, and could sure use some help.
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I would suggest you try using an instrumentation amplifier designed for Wheatstone bridge application. I recommend the INA 125. I would also recommend the TLC2543 12-bit ADC such as used with a Stamp based logger in the following link: [url=http://emesystems.com/OL2tlc2543.htm]http://emesystems.com/OL2tlc2543.htm[/url]
Good luck with your project.
The SDX01G2’s datasheet shows the specs to be rather narrow.
Consider the Freescale MPXV5004 or similar. It’s range (in and out) is far wider than the SensorTechnics model. The 5004 was used in my CPAP project simply because it was a pull from an old CPAP machine.
