# Looking for 3v3 smoke detection sensor **URL:** \ **Category:** General\ **Created:** [May 10, 2015, 4:19pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704 "2015-05-10T16:19:09Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![hl68fx](https://avatars.discourse-cdn.com/v4/letter/h/ea5d25/32.png) [@hl68fx](https://community.particle.io/u/hl68fx)\ **Post date:** [May 10, 2015, 4:19pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/1 "2015-05-10T16:19:09Z")
Hi, I am looking for a smoke sensor to detect a fire. All I could find need 5V. Because I am building a low power project I don’t want to use a level shifter. So i would be very grateful if you could hell me πŸ˜„ Kind regards, Tom ---
**Author:** ![peekay123](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/peekay123/32/810_2.png) [@peekay123](https://community.particle.io/u/peekay123)\ **Post date:** [May 10, 2015, 11:52pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/2 "2015-05-10T23:52:56Z")
@hl68fx, can you elaborate on what type of sensor you are looking for and any links to the ones you have found? You may be able to use a 5V sensor without a level shifter. ---
**Author:** ![hl68fx](https://avatars.discourse-cdn.com/v4/letter/h/ea5d25/32.png) [@hl68fx](https://community.particle.io/u/hl68fx)\ **Post date:** [May 11, 2015, 7:49am UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/3 "2015-05-11T07:49:11Z")
Hi peekay123, I am looking for a MQ2 gas sensor like this one: [Sensor](http://seeedstudio.com/wiki/Twig_-_Gas_Sensor%28MQ2%29) The discription says it detects smoke. I could only find these MQ sensor, but any other sensor who detects smoke would be fine too. ---
**Author:** ![peekay123](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/peekay123/32/810_2.png) [@peekay123](https://community.particle.io/u/peekay123)\ **Post date:** [May 11, 2015, 12:57pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/4 "2015-05-11T12:57:25Z")
@hl68fx, the Grove sensor has an adjustable load resistor (RL) so you can adjust the maximum voltage output/sensitivity of the MQ2 sensor. You can power both the MQ2 heater and Vc (the sensor voltage) with 5V and measure the output of the Grove board using a voltmeter (NOT connected to your Core just yet). Adjust the trimpot to some safe value below 3.3V and then blow some smoke on the sensor to see how it reacts. Adjust the trimpot so the voltage never exceeds 3.3v. Typically, that would be around 4700 ohms or so. Once you are confident that the output voltage will not exceed 3.3v, you can connect it to your Core. If possible, disconnect the MQ2 sensor entirely and measure the set resistance of the trimpot (RL). Then the formula Vout = 5 \* RL / (RL + RS) where RL is the trimpot resistance and RS is the sensor resistance. You can solve for RS, giving (if I’m correct!): ``` Rs = RL * (5 - Vout) --------------- Vout ``` You can then get the ppm from the datasheet chart. πŸ˜„ ---
**Author:** ![hl68fx](https://avatars.discourse-cdn.com/v4/letter/h/ea5d25/32.png) [@hl68fx](https://community.particle.io/u/hl68fx)\ **Post date:** [May 13, 2015, 12:38pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/5 "2015-05-13T12:38:11Z")
Thank you very much for your answer! That helps me really a lot πŸ˜„ I am going to buy this sensor in the next few days and let you know if everything works. Kind regards, Tom ---
**Author:** ![FiDel](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/fidel/32/8811_2.png) [@FiDel](https://community.particle.io/u/FiDel)\ **Post date:** [November 22, 2017, 11:06am UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/6 "2017-11-22T11:06:45Z")
Hi @hl68fx, Does it work with a 3.3v photon? ---
**Author:** ![hl68fx](https://avatars.discourse-cdn.com/v4/letter/h/ea5d25/32.png) [@hl68fx](https://community.particle.io/u/hl68fx)\ **Post date:** [November 22, 2017, 4:31pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/7 "2017-11-22T16:31:31Z")
Hi @FiDel FiDel, in the end I have bought a cheap smoke detector from a DIY market and connected this to my Photon. I was using this tutorial: [http://www.instructables.com/id/Modify-a-6-EUR-smoke-detector-for-use-with-microco/](http://www.instructables.com/id/Modify-a-6-EUR-smoke-detector-for-use-with-microco/) I hope it helps you πŸ™‚ ---
**Author:** ![FiDel](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/fidel/32/8811_2.png) [@FiDel](https://community.particle.io/u/FiDel)\ **Post date:** [November 22, 2017, 6:41pm UTC](https://community.particle.io/t/looking-for-3v3-smoke-detection-sensor/11704/8 "2017-11-22T18:41:27Z")
Thanks for your quick reply @hl68fx! I have already used that type of smoke and CO detectors indeed, but for another project I’d like to use those MQ2 gas detectors. I’ll try it out… πŸ‘‹πŸ‘΄