Inside a flame effect humidifier (with schematic)

let's start this video by taking a look at this device and operation excuse the shaky hands i'm leaning over at an odd angle in the kitchen of the place i'm staying at the moment it's a little unit that has an ultrasonic generator and some leds illuminating that and it emulates a fireplace if i press and hold this button it goes blue and emulates a blue flame if i press and hold it again it goes out which isn't terribly visible at moment but to be honest the most realistic looking one is the orange but enough of this you've seen it working now let's take it apart right it's back at the bench and we're ready to explore interesting the pictures online seem to well apart from the fact the show emulated flames above it which isn't convincing but it is a nice effect it shows a more linear line right across the top here it's not because when you open it up you've got this little separator inside because there is an airport and air is pulled in through the base and it's blown up by a small fan through a tube here and that's what creates a flow of air out and there's a little ultrasonic atomizer over there let's see if we can open this up i should also mention it has a timer function you can set it to one for run for one hour three hour five hours and also uh by holding this button for a longer time it switches between the colors and it's powered by usbc around about one amp not bad say about five watts oh there's the max line for the the water level oh it's a little sticker interesting right let's even get the the unit open and explore the inside so it has little air sticking feet presumably over the screws yes it does right so get them out i'll just stick them back on here because they're kind of interested in seeing the circuitry inside it puts out a decent amount of haze i wonder uh if it's using a fairly standard disc or not i shall use this screwdriver will it reach down into the screws no what are what screws are those uh have i got light here oh what sort of screws are those oh they do appear to be cross head just uh maybe a bit tricky to get the screwdriver into maybe it's the wrong size a screwdriver maybe i'm using incorrect tool that's fine with enough force they will work that's working now i may have just missed it before it says rated input 5 volts 2 amps i didn't measure that i measured a a lower current that's good though oh then it says rated power 4.5 watts which does say you know one amp at five volts well there we go that's uh contradicting information already also get the feeling that uh on these listings they tend to copy other people's listings well that comes off quite easily what's that oh it's a little diffuser for the leds stuck over the back of that for diffused led stuffing so that's quite a complex circuit with double uh double circuitry right tell you what let's take a closer look at this and do a rough assessment to start off with i shall focus on that what am i seeing here i'm seeing the microcontroller i'm seeing a mosfet the mosfet is most likely switching this little piezoelectric disc everything just plugs on here i'm seeing the little circuit board at the back with the leds which also plugs on and i would expect a couple of transistors in the version of this well you know what before i go any further let's just uh take a picture of the circuit board and then we can reverse engineer it one moment please the reverse engineering is complete let's explore the supply comes in in the usb connectors usbc and there are a couple of resistors to tell it to supply well basically unlimited current that uh 5 volt supply then goes via this little smoothing capacitor to a couple of bits of circuitry one of them steps the voltage up to about 20 volts the other one steps the voltage down to 4.4 volts for the microcontroller the 20 volts is switched by this large mosfet here through an inductor to step the voltage up and that then drives the piezoelectric transducer this uh also has a current sent resistor 0.33 ohms to provide feedback on how much current's flowing through it at either side of the circuit board there are connectors for a fan with a little drive transistor and the two color leds the yellow or the blue over here which uh have their circuit on the other side the board i'll bring this in and show you this is flipped over to the back of the board now so there's the fan connector there's the red uh yellow and blue leds and the switch and they've each got the transistor for them under 75 ohm resistor um there is the provision for another led and a bit of circuitry for driving it here i'm not sure what that's for there are the two 5.1 k resistors are used to tell the usb-c port to provide oodles of current oh and there's a 1k resistor and led for each of this sort of like level indication indicators i think it's timer indication right to get that out of the way and i shall bring in the schematic it's a very busy schematic it's quite full because there's quite a lot going on so here's the usbc connector and it has two pins marked at well they're called cc1cc2 and if you put a 5.1 k resistor from each of those pins to the zero volt rail it tells it to supply up to about three amps there is the uh small smoothing capacitor what value was that just uh hold on let me just double check that right now at 220 micro farad 220 mega fart 10 volt that's all it has to be it's only getting 5 volts at that point in time the five volts uh then feeds a multiple parts of circuitry it goes to the voltage regulator and gets converted down to 4.4 volts that might seem quite an odd voltage but there they've done that to give it a margin below the five volts so the undulation of the five volts with the pulsing other pulsing loads the other power supplies doesn't affect that but um the 4.4 volts also gives it extra for driving notably this mosfet here for stepping the voltage up and also for mainly stepping the for the piezoelectric mosfet which is the harder the gate voltage the better the lower resistance it will turn onto so the 4.4 volts is also used to power the little indicator leds with 1k resistor each because they're not much current um and that's it the microcontroller is the push button input pulling it to the zero volt rail for changing modes and colors and the and turning on and off and setting times and also drives the transistors the ordinary npn resistors j3y that switch the yellow and blue leds there's two sets of these and the fan they just have one key resistor to switch out that um the step-up circuit that steps the voltage up to the higher voltage before it gets pulsed by the piezoelectric circuitry involves this 10 micro henry inductor a our ardp mosfet that's this tiny little mosfet here and it equates to an ep 3n06mi rated 60 volt at three amps and it's being used to boost the voltage up to the piezoelectric section and to do that the mosfet is being pulsed by the microcontroller which is unusual i thought this was going to be dedicated boost circuitry but i've seen this being done before there's a possibility it might be being pulsed at the same frequency as the piezoelectric circuit which would make sense as well but there's a 10 megahenry inductor there is a shortcut diode for the high speed operation of that and then there's a little array of components here there's a recovering capacitor smoothing capacitor 1000 mega fart 35 volts there's a 24 volt zener now i actually filled the unit with water and left the circuit board hanging out the side and then measured the voltage it only went up to 20 volts but that's just you know they've just got 24 volts in there to cap that so it doesn't go too high and then there's a 2k resistor across it not sure the point of the 2k resistor but it will result in a slight load just as maybe it's a worst case scenario maybe it just now helps to load off this zener diode if the voltage starts going too high maybe if the piezoelectric became disconnected in some way that is the very cluttered power supply circuitry and microcontroller circuitry now over onto the next bit the circuitry which is the most interesting bit in the way although the other stuff has its own merit there is a mosfet 12n10 that's being used with this 10 micro henry inductor um and it's pulsing that but it's also measuring the current with this 0.33 ohm resistor there's a capacitor across that i wonder if that's just so initially when it uh turns on it will be discharging effectively this circuitry here so there might be a current spike maybe it's just to mask that current spike or to provide stability but then there's a 10k resistor going over to the microcontroller that can sense a voltage there and it can measure the current going through the circuitry in that way uh this mosfet has the classic 10k pull-down resistor and it's got a 10 ohm series resistor from the microcontroller to limit the peak current as it charges the the gate of the mosfet and when the mosfet turns on it current starts flowing through this inductor building up a magnetic field in it but it also shunts any charge that has built up in this capacitor and the piezoelectric transducer which are in series there is the option for another capacitor in parallel possibly for fine tuning not sure but that's a when the mosfet turns on it's putting magnetic field into that also completely discharging any charge on this capacitor and the piezoelectric disk and then when this turns off uh the magnetic field collapses and it will provide quite a high voltage pulse to that so alternatively alternatively the piezoelectric transducer is being charged to a high voltage and then it's being discharged to zero volts so it provides sharp and high voltage pulses i'm not sure the voltage will be in this it will be determined by the inductor value and the the capacitance the combined capacitance of the series capacitor and the piezoelectric transducer very interesting the transistor itself isn't like the little gp water atomizer ones that you get that have the holes perforated through a disc and a sort of ring of material this one is a dedicated um transducer for creating [Music] the plume of water and atomization in those tanks so it's very similar to the classic piezo discs you find in the ultrasonic water atomizers but this one's a bit smaller and it's got a printed surface conductor on the front um which uh folds over the side here to connect to the back with conductive ink and then there's a small pad in the back but it's worth noting that uh to protect the metallization here they've also got us printed on a shiny layer can i can i shine that i think you can more or less see it shining hold on a show zoom down so you can see it better and i shall focus onto that so it's got that shiny layer i'm trying to point at a light i'm completely failing to point a light here um yes anyway yes you can kind of see the shiny layer on it there is um and that's presumed to protect it but it is a classic fairly thick ceramic disc the color is suspiciously close to some ceramic capacitors i wonder if there's a relationship there in the ceramics used but that is it this disc is then inserted into a silicon rubber surround with the wires coming out the side and then that is clamped on the back of the water tank and where's the water tank here it is in this port with this clamp that just presses on thumbnail round and ensures it's smooshed in and doesn't leak water the other side has a little fan here which is just pushed onto pins slightly tapered pins to actually hold it in place very simple and interesting construction it's a good effect the circuit board is heat staked and i can't get that out without breaking it out uh hold on i should just uh here yeah that's kind of heat stick that is heat staked onto a little pin at the back this little rib here that just basically clamps those leds in position but as far as i can see it's just 10 leds in parallel for each color technically speaking i could calculate how much current will flow through these leds because they are being powered from the 5-volt rail just give me one moment please i'm just unlocking my phone so they're being powered by the five volt rail the typical voltage across them will be three volts that's five minus three is two volts divided by the 75 ohm resistor is they're going to be about it's only about 26 milliamps that's less than i expected um but there we go and that's not stressing them at all i mean it doesn't have to be too bright it's just a very gentle effect it's not designed to light the room but that is it the piezo electric transducer little water plume generator that is the leds pointing up into the tank here um and uh out the port of the top and uh just creates the fan assisted flow of uh water vapor that's created by the ultrasonic atomization from this port here and that creates that sort of hazy decorative fake flame ultrasonic effect it's quite neat it looks quite smart

Channel: bigclivedotcom

Views: 101,509

Keywords: eBay, ultrasonic, water, humidifier, flame, fire, effect, usb

Id: iXKARsAv2B4

Length: 14min 49sec (889 seconds)

Published: Sun Aug 21 2022

Reddit Comments

[u/nemom]

From the description:

"""

These seem to be pretty common on eBay, so I got one to take to bits.

The circuitry is quite evolved, with a microcontroller controlling both the ultrasonic atomiser disk and also a boost circuit for stepping the voltage up.

There are locations on the PCB for extra filtering, that have been bridged by zero ohm links. I'd guess the designer wanted to keep their options open. That's also reflected in the extra LED position, allowing the PCB to illuminate a water container directly. I'd guess this PCB may find its way into other products too.

"""

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