Vape inhale sensor - Page 1
Forum section: electronics / projects

author: RoGeorge
author_rank: Super Contributor
timestamp: August 15, 2025, 09:50:41 am
content: Usually the electronic of a disposable vape is just a round capsule with 3 pins, looking exactly like an an electret microphone, with a LED soldered on the other side. All the electronic is embedded into that, including the LED fade and the ON/OFF MOSFET for vaporizer heater.I've tear apart such an electret microphone looking like sensor, and it does seem to contain the same parts as an electret microphone. Then, I've read electret can be sensitive to very slow pressure variations, too, so at this point I don't know if the inhale sensing is made by measuring the negative air pressure during an inhale (very low frequency), or by measuring the hiss produced by the air (very high frequency), or maybe by a combination of both?This small board from a disposable vape I've just found (brand VEEV?), however, is different.It has a relatively big PCB (about 1 square centimeter, the marks on the green ruler are at each 1mm), and has discrete components. A microcontroller (not marked, probably a custom OTP), a 50m\$\Omega\$ MOSFET 3415 for the heater, and an RGB LED.Most intriguing, the inhale sensor looks like a MEMS sensor, and it does not directly control the heater (like a typical inhale electret-like sensor would do). This sensor is read by the MCU, and the MCU has another pin controlling the gate of the heater's MOSFET.The markings embossed (twice) on the top side of the metallic can reads PG43D166 for the sensor in the pics, but I couldn't find any datasheet/info resembling that code. On the top side, the metallic can was covered by a thin layer of auto adhesive foam (now removed). Yet, on the other side of the PCB, the encircled hole goes downinsidethe metal can of the sensor, so the can of the sensor has a hole in it on its bottom/soldering side.Anybody happen to know about this sensor, datasheet, or what it is, or how it is supposed to be working? Asking mostly out of curiosity.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 15, 2025, 12:23:04 pm
content: Meh, the inhale sensor is digital, default OFF.Probed it with the oscilloscope. The sensor output goes to ON (+V) only when the air travels from bottom to top (through the metal can). In the other direction it does not trigger. Also, it is not sensitive to noises, and not sensitive to mechanical shocks either. So, however it would be working, the output suddenly goes to high only when a sustained (and pretty strong) airflow passes through it into the right direction, and with enough speed (tested with a plastic straw).Also, the LED is most probably not RGB. It has 4 individual pins, but on the PCB two pins are tied to V+. Only red and blue (or maybe UV/white?) can be seen, not that it matters.Fun fact, on the raw battery cell (Li-ion 680mAh) it is explicitly written "Rechargeable".First time when I see this written on a raw Li-ion cell (as apposed to some other raw Li-ion cells also from disposable vapes, on which it was explicitly written "Do not recharge", yet they were recharging just fine).

author: voltsandjolts
author_rank: Unknown
timestamp: August 15, 2025, 12:32:46 pm
content: You mean U2 is digital 0/1 output?Looks like standard mems microphone to me, but maybe its a custom thing for vapes.

author: tooki
author_rank: Super Contributor
timestamp: August 15, 2025, 12:52:47 pm
content: Quote from: RoGeorge on August 15, 2025, 09:50:41 amhttps://www.eevblog.com/forum/repair/what-the-hell-is-this/Quote from: voltsandjolts on August 15, 2025, 12:32:46 pmVery custom. See link above.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 15, 2025, 02:10:08 pm
content: Quote from: voltsandjolts on August 15, 2025, 12:32:46 pmYes, this one has a digital output, only 0V or +V, no other voltage levels in between, not even when the airflow is increased or decreased slowly. It is all or nothing. So, digital, but not as PCM or I2S digital output, but digital as an on/off output, with time debouncing, and with airspeed hysteresis, all processed by the sensor itself before switching its output on or off.From other reads, the inhale sensing can be made in many ways. That's why the hope. Some can even detect the airspeed, in order to adjust the heater accordingly.Because this little PCB was using discrete components instead of a single dedicated IC, I was hoping the little metal can to be just a cheap MEMS microphone, so with no filters and no logic inside. But it wasn't so, this one can output only 0/1, and has all the air detection logic included.The hope was to reuse the little PCB as an ultrasound microphone.Some time ago I've tried a few ultrasounds receivers (to hear bats). Since then, I keep hunting for microphones good up to 100kHz, or maybe even above that. Every time I bump into a new model of microphone I test it (they are all over the place, in headsets, mobile phones, TVs, landline phones, boomboxes, toys, etc.). Testing everything that looks like a microphone, because it's a matter of luck to find any that is good above 50kHz. Recent microphones will usually include an embedded preamplifier and filters, some may even include a small DSP, so most nowadays models are not usable outside the audio range.

author: voltsandjolts
author_rank: Unknown
timestamp: August 15, 2025, 03:32:16 pm
content: Quote from: RoGeorge on August 15, 2025, 02:10:08 pmMyPistrelledetector works quite well and uses SPU0410LR5H-QB for the microphone.I bought a few of that mic earlier this year but now seems they are obsolete and out of stock.Edit: Whoa, I said 'My Pistrelle' as-in I own one copy, I didn't design it!!

author: RoGeorge
author_rank: Super Contributor
timestamp: August 15, 2025, 05:04:41 pm
content: Nice idea with the PCB the same size as the battery holder, so to form an enclosure together.Thanks for the mic type, good to know. The best I've found so far is an electret microphone from a very old mobile phone (Motorola 8700), tested up to 200kHz or so (the one at the right end side of the breadboard):Next in line with a decent ultrasound response is an analog MEMS from a (Samsung?) mobile phone, modelF4-(S)MOE-N090R38-3Pmarked "ME V1.0", it was working up to about 100-150kHz:https://www.eevblog.com/forum/projects/want-to-hear-the-bat-flying-in-my-front-yard/msg3639214/#msg3639214Since I don't sell bat detectors, I never order microphones, so no idea if this analog MEMS mic is still in production (in case you want a replacement for the discontinued model you used to use).

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 16, 2025, 01:40:38 pm
content: Good Morning RoGeorge, perhaps you could look into a hearing aid circuit. Amazon has cheap hearing aids for around $50.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 16, 2025, 02:23:38 pm
content: Will keep in mind, thank you.

author: jonpaul
author_rank: Super Contributor
timestamp: August 16, 2025, 06:07:05 pm
content: Vape = Chinese poisonJust dont do itj

author: RoGeorge
author_rank: Super Contributor
timestamp: August 16, 2025, 06:16:56 pm
content: I don't, just that I can't resist picking up the empty ones I find, knowing they have a Li-ion rechargeable inside.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: August 16, 2025, 07:07:04 pm
content: The ultrasonic world is full of amazing discoveries. I once borrowed one and was amazed at how many small insects produced sounds in the ultrasonic range.Works good finding diminutive gas leaks.What frequencies are the bats emitting sound?

author: RoGeorge
author_rank: Super Contributor
timestamp: August 16, 2025, 11:12:40 pm
content: Depends of the species. Probably the most common are using no more than 50-80kHz, but some are using up to 150kHz or so. Above that it is not so common, too high frequencies doesn't travel well through air.You can find online the frequency/spectrum of each species, and records translated into audio, too.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 17, 2025, 06:15:01 pm
content: Its a MEMS airflow sensor.egwww.aldvapor.com/utilizing-mems-sensors-for-enhanced-e-cigarette-performanceNasty antisocial habit.