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I am trying to use TGS 2602 sensor of air contaminants. I would like to test if my circuit is working as intended. For that purpose I need to generate fumes of one of the gases the can be detected by the sensor.

TGS 2602 sensitivity characteristics

I thought that I would go for ethanol. I tried holding vodka soaked cotton ball near the sensor - to no avail. Later on I tried spilling vodka around the circuit and placing more vodka soaked cotton balls around. I also covered the whole thing with a cardboard box (with gaps at the bottom between table and the box). Again there was no considerable effect. Vodka is essentially ~40% ethanol and water mix (by volume).

Can you say by that short description that I managed to generate between 1 and 100 ppm ethanol gas? If not, can you propose a robust and safe method of producing such a gas?

Please be aware how the sensor looks. It is enclosed in a metallic case with small holes on the top surface.

TGS 2602 sensor

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  • $\begingroup$ Are you certain that the wiring and power supply 5 V DC for sensing and for heating are correct? You might want to look at the datasheet. $\endgroup$ – Klaus-Dieter Warzecha Feb 3 '17 at 12:54
  • $\begingroup$ @Klaus Warzecha - that is what I am trying to establish. I am using a somewhat more complicated circuit, because I am using digital rather than analog reader. Anyway when I replace the sensor with resistors (~57 ohm for the heater and ~10k or ~100k ohm for the sensor itself) the circuit seems to work - nevertheless I am not 100% sure that it is functioning as intended, therefore I would like to create a testing environment in which I should have prior knowledge that sensor should be sensing something if it was working correctly. $\endgroup$ – user40790 Feb 3 '17 at 13:07
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    $\begingroup$ How to do it, and how to do it cheap are two very different problems. $\endgroup$ – MaxW Feb 3 '17 at 16:36
  • $\begingroup$ If the 40% alcohol solution came to vapor-liquid equilibrium at room temperature , then the vapor concentration of ethanol should have been on the order of 2%. $\endgroup$ – airhuff Feb 3 '17 at 18:41
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Waving a vodka soaked cotton ball near the sensor is sufficient to generate the required fumes. It was the circuit that was problematic - I did a subsequent testing with analog reader (voltmeter to be specific).

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