u/hanasamaaa

‎help! we created a co2 monitoring system using 2 MQ-135 gas sensors. the catch here is we were tasked not to use any microcontroller and instead opt for ics. we used lm358 as the averaging amplifier and lm3914 as the driver of the leds.

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‎we tried prototyping it using a breadboard and it works fine! the issue here is after implementing it to a pcb and soldering all the components, it doesn't work as intended now. the white led (lowest ppm) always turns on but so as the yellow led

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‎attached is our current schematic.

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