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ostaquet / Arduino-MQ131-driver

Arduino driver for gas sensor MQ131 (Ozone / O3)
MIT License
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Load resistance with 3.3V microcontroller #54

Closed ostaquet closed 1 year ago

ostaquet commented 1 year ago

hey just wanted to tag on this issue, I'm using the ESP8266 that also has a 3.3v ADC that I'm also using a voltage divider, what do I set the load resistance to?

Originally posted by @lackdaz in https://github.com/ostaquet/Arduino-MQ131-driver/issues/50#issuecomment-1202028529

ostaquet commented 1 year ago

The heater circuit requires 5V. It is the power required to heat properly the sensor and burn particles of gas.

The sensing circuit is just a resistance based on the voltage provided by MCU. In the example, the MCU provides 5V and accepts 5V on ADC converter. As you are working with 3.3V MCU, you can use the 3.3V power line on the sensor circuit and wire to the analog pin of the MCU. It should work as the couple RL and Rs will simply divide the input voltage of the sensor side.

You can keep the load resistance as-is but power the sensor circuit of the sensor with 3.3V.