I am building a breathalyzer but I cannot use any programmable chips. We are using a comparator circuit to analyze the voltage output of the alcohol sensor. The problem we are having is that the output voltage of one of the comparators is 2V while the other is at the 5V we need to turn on the l.e.d. We are looking for a way to clean up the signal so that only one led is on. We tried using an inverter but 2V makes it go high so we are looking for another option. Thanks in advance for the help!
https://www.electro-tech-online.com/custompdfs/2010/03/MQ-3.pdf This is the url for the sensor.
We are taking the output from the sensor and feeding it to the inverting end of one comparator and the non inverting into the other comparator. The other input of each comparator is tied to a voltage divider to create the desired reference voltage to determine whether the output of the comparator is high or low. When the voltage is below Vref, there is 5V at one comparator and 2V at the other. We need a way to make the 2V zero because that voltage is allowing the wrong l.e.d. light up. I'm sorry I don't have a schematic... we have been troubleshooting this for a while. The voltage coming out of the comparator that should have a zero voltage is a little about 2V which means we can't use an inverter to clean the signal.
We actually changed the load because the voltage levels weren't where we wanted coming out of the sensor. Vref is set to 4.68V. Is there a simple way to clean up the output? We just need to be able to have one at 5V output and the other at 0V so that only one led is illuminated at a time
We actually changed the load because the voltage levels weren't where we wanted coming out of the sensor. Vref is set to 4.68V. Is there a simple way to clean up the output? We just need to be able to have one at 5V output and the other at 0V so that only one led is illuminated at a time