Gas Sensor Board Write Up
Virgil
Posts: 6
Previously Posted this thread under Sensors.... Should perhaps be posted under this category ....
This maybe very old news.... but was recently reviewing the Parallax CH4 Gas Sensor Module information... I believe that the Op-Amp descriptions in the Theory of Operation does not correspond with the U1A and U1B identified in the schematic.... U1A in the diagram is an op amp in the comparator configuration and U1B, the second half of this dual op-amp, is the unity gain op- amp buffer... In the Theory of Operation write up the A's and B's perhaps, should be reversed.... Maybe an upgrade in the hardware at Parallax which was not reflected in the 2010 circuit diagram.... a very small item....
Virgil...
This maybe very old news.... but was recently reviewing the Parallax CH4 Gas Sensor Module information... I believe that the Op-Amp descriptions in the Theory of Operation does not correspond with the U1A and U1B identified in the schematic.... U1A in the diagram is an op amp in the comparator configuration and U1B, the second half of this dual op-amp, is the unity gain op- amp buffer... In the Theory of Operation write up the A's and B's perhaps, should be reversed.... Maybe an upgrade in the hardware at Parallax which was not reflected in the 2010 circuit diagram.... a very small item....
Virgil...
Comments
Thank you for bringing it to our attention.
You are correct. In the draft schematic I had U1A on the left and U1B on the right. However the person who laid out the PCB altered the order for efficiency in the layout and I did not catch that while writing the documentation. It doesn't appear that we currently have this documentation for download and this product was discontinued and replaced with a unifying PCB for all of our current gas sensors, so I probably won't update the documentation. I did verify that the current documentation has the op-amp references matching the schematic. This is for the Gas Sensor Board (#27983).