I am confused why both the SN-MQ7 and SN-MQ9 sensors' pin2-VCC and pin3-GND are interconnected ? Can someone help me?
JaneYu 2015-04-28 22:19:09 20 Views11 Replies I am confused why both the SN-MQ7 and SN-MQ9 sensors' pin2-VCC and pin3-GND are interconnected ? Can someone help me?
What type of connector is used on this board? I need to buy the male in order to create custom cables.
JaneYu Hope this can help you. The hole size is 3mm.
https://uploads.disquscdn.c...
JaneYu It is better to attach you connection here. what is kind of MCU are you using now? What about changing another analog port?
JaneYu it said that cannot read analog voltage value
I think connections of pins are exact
Do i have to preheat the sensor before i measure it's voltage?
JaneYu Does this board cycle the sensor VH properly between the 60 second 5v heating period and the 90 second 1.4v sensing period?
JaneYu It does not. Red wire needs to connect to a PWM output (assuming it can drive enough current). The diagram/source code in the wiki will not work properly because the heater voltage is constantly at 5V.
Hi, i want to plug this into a Raspberry Pi2 and just want to check, the 10K resistor is built in, so I only need to connect to 5v GPIO, GND and to my ADC MCP3008 Ch0 to get it to work? TIA
JaneYu Can i directly supply 9v battery to the sn-mq7 sensor?
JaneYu No. the operating voltage is only 5V, 9V power supply will break the sensor and MCU
Could you tell me how you convert the output voltage to the gas concentration in PPM? Thanks,
JaneYu You could check the schematic.If you don't power it, the resistance value between H sides will be very small, which you could almost ignore it directly, But once it gets a power, you could measure it with a multimeter, It will change.
JaneYu 
