Inside a Homedics steriliser unit - with schematic
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- เผยแพร่เมื่อ 7 ก.ย. 2024
- This is one of many similar products that cashed in on the pandemic by offering products that would sterilise phones and other objects with UVC energy.
To be fair, this one has a better design, since it allows for greater distance between the UVC LEDs and the object, and it actually drives the LEDs at a fairly significant current. It could actually find use as a lab sterilising device, although the LEDs can't yet compete with traditional mercury vapour UVC sources.
The circuitry in this unit is surprisingly complex. It has the signs of being a "proper" design without the usual penny pinching shortcuts found in similar products. The thermal sensing in the lithium cell is a nice touch, but can't really protect against charging at very low temperatures. It seems mainly to protect against cell overheating.
The way the voltage booster is controlled by software is odd, but presumably more versatile. It appears to be using a fixed voltage and a low value resistor in series with the LEDs to set the current.
One good thing about the pandemic and the flurry of dubious sterilising products is that the development of UVC sterilising LEDs has been moved forward significantly by creating a huge market for them.
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#ElectronicsCreators
Homedics is a pretty well know brand in the US, and they're known for making rather sturdy devices that tend to do the one thing they're designed for well. Most of their things are more along the lines of massagers and light weight home medical equipment (pulse oximeters, blood pressure monitors, etc). I'm only a little surprised to see a UVC device from them, but not shocked to find that it's well designed and well made.
I couldn't have put it better.
Homedics stocks go up
So this is for sterilizing the back massagers and other body-touching products that might pick up stuff .
it may be well made but it is still designed to be bought by the ill informed. UV is a rubbish way to sterilise a phone.
Lmao I wouldn't say well known, from a quick google their website is like a QVC infomercial.
If it's 'HoMedics' you can rest assured that it's not cheap junk. HoMedics make proper medical devices which are, or used to be, sold by Boots the Chemist. I have one of their digital electronic blood pressure monitors, and it's right on the mark when checked against my GP's 'Omron' model. It's well made and accurate, and even though its onboard calendar has expired, I still use the monitor because it's easier than my new one, and no less accurate!
HoMedics might not be top notch hospital grade, but it's far better than the cheap kit you can buy online, and is supplied by a well known and respected company.
I thought it was HomeDics until he pronounced the name near the end of the video lol
Well designed! But we have seen so many UV sterilizers that put out no UVC, so I would be skeptical until I see it pass the famous Clive's Green Banana UVC Test. Thanks, Clive! 👍
yeah, he should get that checked out..
It's a Homedics device, it'll do exactly what it says on the box, well.
My mom works in sterile supply at a hospital and her tech she uses is amazing. Your channel has gave me some things we can talk about... thank you
I almost moved on but when you showed the circuit board I realized that this just might be a serious device. Your 3 pager circuit confirmed that. So, I learned much. Cheers.
Clive, I wonder, will it work as a uv prom eraser? :-)
Not sure if the wavelength is ideal for EPROM erasing.
I got the same thing from Lidl for very cheap a while back. I just drive the LEDs directly from a bench PSU to wipe EPROM chips. It's a bit slow but works just fine when not in a rush :)
At least it puts out some actual UV-C. Remounting the LEDs side by side in a proper box would make a decent UVilizer.
Do you smell ozone with these LED'S?
@@LutzSchafer No not at all
Clive, have you not read Hitchhiker's Guide to the Galaxy? An entire planet's population died after they sent away all their telephone sanitizers, deemed useless workers, on an interstellar trip to a (supposed) new home planet.
Aw I wanted to see lots more details about the UVC LEDs!! This is the first time I've ever seen a device without the usual sky blue diodes in line with the UVC chips to act as safety warnings. That makes them potentially useful for other stuff like illuminating fluorescent minerals for viewing etc. But I need to see how MUCH light it's actually putting out to see if it's worth it to buy. At 200mA and 6V each that suggests a total power consumption of a couple watts, and given the abysmal efficiency of UVC LEDs I'd guess they're putting out maybe nearly 100mW, which could be useful for some things like observing willemite and terlingua type calcite phosphorescence, especially at $7!
Great teardown.
Yeah, I too was hoping for a closer look at the UVC LEDs.
Are they in a UVC transmissive case style (hermetic with quartz window)?
What is the centre wavelength?
They are pretty low output compared to a mercury vapor tube, like I put one in a similar device against a UVEPROM window and it took something like 45 minutes to start flipping bits.
@@KallePihlajasaari they are quartz windowed and the center wavelength is 280nm. We've done a simple mod on the fluorescent minerals subreddit and it's at least as bright as those 4 watt UVC lamps intended for fluorescent mineral viewing and at 1/10th the price!
Great detective work on circuit design, one of your more upscale devices you have shown us.
I still don't think I'm going to get myself one in the near future.
I built my own in the pandemic for about 20€ using a large plastic Makita box, foil tape and a UVC fish tank lamp. No safety interlocks or anything like that, just put stuff in, close the lid and turn it on. The sweet smell of ozone is proof positive it works.
Homedics is a serious brand. I've yet to find a UV steriliser big enough for my smartphone.
LOL
According to the website they were originally selling this for £79.99 🤯
Very interesting unit!. My friend bought a similar device yesterday, and of course I've "tested it" already. It cost 6 euro (!!), down from 40 euro, cause it went out of fashion after main covid spike. It's powered from USB-C (charger is not included), stating maximum consumption of 9V/2A, which looks like it can negotiate quickcharge. It features a shitty induction charger (so it can charge phone when sterilizing it), and pretty interesting 254/185nm sterilization. To my shock it features two "true" mercury discharge tubes inside, looking like old-fashioned xenon flashes. It obviously works, because after you open it there is this pungent acrid smell of ozone, with amount enough to make you cough after you "sniff" it. To my wonder the quartz (or even sapphire) tubes are behind some kind of yellowish translucent plastic, with color looking similar to kapton. I wonder if it is translucent to UVC, or if it makes only ozone behind it and the plastic is transparent just so you can see the tubes. I must buy it, with this absurdly low price it is worth just for the interesting discharge lamps alone. Model goes by the name "MAGINON ST-1QI".
Interesting device!
I am a bit shocked that there seems to be no monitoring of the UV-C LEDs. Means that the user will never notice, if something fails and things are not sterilized.
I worked in projects developing two pretty similar products for water. Monitoring was a huge topic and taken very seriously.
There are a lot of products with zero monitoring.
That's what the sense of the LED voltage is for
The mysterious boost chip is probably of the constant current type hence the sense resistor. So many things can be monitored here
1. Switch on the mosfet and watch the LED voltage. It should be Vbat minus the diode drop of the shottky. If not, the LEDs are shorted or the diode is blown
2. Enable the boost chip. Now you can monitor the LED Voltage under constant current. If the voltage goes high, at least one LED is open. Also the LED voltage is dependent of their Temperature. If the LED gets hot, the voltage gets lower, so maybe this is also to protect against over temperature. and of course if one LED goes short circuit the voltage will half
And what also comes to my mind is some kind of dose control
From voltage and current you can very precisely work out the output power of the LEDs (voltage at current gets temperature und thus efficiency)
Over time you get rising temperature and decreasing efficiency
The difference between your product and this one here is that sterilizing water can actually be useful as you can get seriously sick from drinking contaminated water. On the other side, it makes absolutely no difference wheter your phone as actually been "sterilized" or not. If you want your phone clean, wipe it off.
If it's under software control, it's not a safety interlock. Should've used a reed switch on the UV LED power rail.
I've found those LED based steriliser units aren't all that useful as their outputs are so low, they've gotten a lot more efficient but the mercury tubes always achieve higher intensities which is essential for proper steriliser or UV EPROM erasing. Expect it to take multiple hours to erase an EPROM in one of those if you just place it on the bottom, maybe half an hour if you place the LED right on the window.
That's definitely true. Mercury vapour lamps are much more efficient than LEDs, at UVC wavelengths and cheaper too. There are a few advantages of LEDs though: no toxic mercury, no glass to break and they should last longer, as long as they're not over-driven.
Vince is a star!
Thanks for the insight to very serious product... 🥰
If you had children (young adults) in your household whom are permanently attached to their phones you might get the purpose of the device in regards to grubby hands and bathrooms...
A very well designed device...I'm really impressed!
Good morning Clive from the other side of the planet. Wishing you all the best. Take care old friend.
Look, an EPROM eraser! Nice board indeed.
That's what I've been using my UV sterilizers for. Both UVC LEDs and tubes seem to work fine.
THat's what I use this for. Although have to provide direct power to the LEDs, the timer only runs for a few seconds and I have to blast the chips for about half an hour for a good FFFF experience.
Quack sterilising aside, it seems like a great little portable curing station for UV Resin repairs!
I just went over to Mouser's website, and found them selling UVC (less than 280nm) LEDs. They are a real thing !
Vishay & Lumex are some known component makers that sell them thru distributors, like Mouser. A Vishay part that draws 120mA with a nominal 6V drop, runs for ~$3.60 if you buy 10, or more. 5 bucks in single unit buys. 30mA units also available, but only a buck cheaper. This is as of Sept 2023, when this comment is posted.
A decade ago I made myself a photoresist cooker out of 10 1A 460nm diodes, and I haven't even try them under 1A, because under 400mA, and mounted on properly calculated huge radiator taken out from old equipment they become double purpose cooker - I can also warm my lunch. Probably there are newer and more efficient UV LEDs, but as I've heard the shorter is the emitted wavelength the lower is the efficiency.
I guess you don't have your UVC test cards to check that the output is really what it says it is. Although, the competency of the design and implementation would suggest that it doesn't have anything to hide.
Unless a bean counter replaced the UV LEDS for cheaper components like doubled 3V leds .
@@johndododoe1411 They didn't, mine erases EPROMs.
That’s because they continued to beat the drum about fomite transfer, and touch/object communicability. Even though there was never a single verifiable case of fomite infection anywhere in the world. Gave them another excuse to lock everything down.
Nice device, "unexpected professional design". 🙂
The reason the MCU pulses the thermistor is because if you keep the current flowing continuously it noticeably raises the thermistor junction temperature, by a few degrees. Very complex circuit for what is essentially a torch.
I find those hook tools that mechanics use to be really useful for those stinky little plugs. The small ones are great for a lot of tiny stuff like that I find
that would be great for UV EPROMS, if anyone remembers those. I'm so old I started programming before the EPROM was invented. I spent many days chiseling ones and zeros into stone programming cards.
Probably not the ideal wavelength for that.
I've got a Homedics footbath sauna, very nice. They make great stuff.
You bring the real maker spirit. Keep it up! Also I love the carbonation videos, make some more of those if possible : D
I love your breakdowns Clive and the UV equipment is of particular interest. However, any manufacturers worth their salt who claim UVC output should qualify what the 254nm "Germicidal" intensity is so a corect exposure time (hence dose) may be calculated.
It would be so helpful if your excellent videos could measure or at least estimate the UVC power.
The cost of a proper lab grade device that can analyse wavelength and strength of UVC accurately is unfortunately absolutely prohibitive.
Vince The Crew Chief has finally found someone to clear out his electronic tat collection!
Fumblesome...great word, so descriptive. I will be stealing that, if you don't mind...!
hi from Sweden Clive. Me and my Daughter loves watching your videos together!
The classic 4056 charge chip. Nice bit of Eric O. terminology there (not a sponsor).
I have a Psion Organiser II. This might work to format the Datapaks :)
Clive.
Just to let you know that if you hear a loud rumble on the IOM it might be a monster truck, Kevin Talbot is moving over there and might be talking his truck. 😆
Also re. Edinburgh tattoo dancers colour changing clothes. I told my mum what you said and she was surprised, my dad had no idea what we were talking about. 😆👍
Surprisingly well made. The main purpose of the device appears to be extracting money from people who have no idea how viruses transmit. If there is virus on the surface of your phone, it got there from someone who used the phone, probably you. So sterilising it is a bit late. Maybe you want the device so you can sterilise your phone after lending it to somebody. In that case, an easier way to decontaminate your phone is to not lend it to anyone so it never gets contaminated. The manufacturer is just cashing in on peoples ignorance, but at least they did manufacture the device properly.
Fumblesome; one of the best Cliverisms ever. Now in my everyday vocab 😂
Thank you. Keep working, good luck.
These are commonly used to sterilize small devices that are used by multiple people in institutional settings; the example I'm familiar with is the shared remote control in a seniors' home. They're also used by health care providers on their own electronics and jewelry to lessen the risk of pathogen spread between home and work.
Fun fact: when hospitals in the 70s were trying to reduce infection rates in hospitals, they identified two unexpected germ carriers: nurses' caps and doctors' neckties. Nowadays it's cell phones and earbuds.
These devices aren't permitted or approved anywhere near a hospital or healthcare! IDK what back alley clinic you're going to but nobody in 1st world modern medicine is using these, you might find them at a nail salon with all the other cancerous chemicals and polish hardening UV lights
I bought something similar at around £27, nice white plastic box, pretty pattern on it - and bloody blue LED’s, no UV 😤
Cleve would be interesting too looks at one of these sterilizer waters bottles.
Why do people sterilise their phones? When was the last time you did a number 2 without your phone?
Where I live, food handlers are not allowed to use their smartphones at work, due to mouth proximity.
The devices that were designed for the pandemic have not suffered the 'race to the bottom' of other long-term devices (short of the purposefully scam products).
This might explain the quality of the design?
I don't know about sterilizing cell phones, but one of these would be great for blasting actor mics to keep the creepies and crawlies away. Maybe why Vince had it.
All plastic is "as black as the inside of your grandfathers hat" as they say. That silver reflector at UV-C wavelengths will be black. As a result only surfaces facing the UV-C LEDs will be sterilized and then only if enough UV-C is emitted. The sides and back of any object put inside would obviously see no direct light. You need a total dose of 60J per square meter to sterilize most viruses and that is quite a lot when the LEDs only emit a few milliwatts. Added to which the LEDs send most light straight downwards and very little to the sides so the exposure won't be even across the object inside. Remember if you are working with UV-C LEDs you should be very careful about exposure to the light. A thin sheet of clear Acrylic will block all UV-C and you can see if the LEDs are working because they will glow a dim white/purple colour.
The feedback for the boost chip is puzzling, normally the feedback comes from between that 2R2 and the LEDs, a 204mV reference is common for those chips which would make 2R2 and 1R74 in parallel exactly 200mA. Are you sure those two resistors aren't in parallel? Look at the TPS61169 for example (it's even pin compatible excapt for one unused pin)
The mechanical design is more interesting than the electronics :) Question is, are those two UVC diodes actually effective? Maybe you should join up with Applied Science to have him test it!
Looks well made. Wonder if you could repurpose this to erase eeproms. Serious eeprom erasers are specialized and expensive. Everything else readily available is on the complete opposite end of the spectrum and is the cheapest and most suspect kit you can find.
I believe real uvc diodes put out 254nm wavelength which I think is appropriate (Experts feel free to chime in!)
Probably not the ideal wavelength for that. The classic UVC LEDs are not as shortwave as UVC tubes.
Currently on Amazon for less than $9 US - worth it just for the lithium battery!!!
WE used to sterilize our Android phones by rubbing them with Isopropanol hand gel during Covid, just didn't put too much, in the USB C port, as it thought it was wet and told you so.
Hmm... I guess, nowadays, a Hall effect sensor is cheaper than a small reed switch?
Try "t" pins. They're great for removing those little rubber screw seals.
Douglas Adams had a thing or two to say about telephone sanitizers 🤔
Probably fantastic for field reprogramming of EPROM
Not the ideal wavelength.
@@BigClive That's a shame. It could have had a good purpose.
Very interesting insides, a lot more than I thought, not the typical cheap Chinese knock off. Nice 2x👍
Nice teardown, but didn't notice on your schematics where the third connection from the battery went? I presume it's an NTC feeding the 4056?
It's the NTC drawn to the right of the battery on page 1 . This is actually the standard 3 pin battery connection arrangement used in other products and supported by battery control chips .
The charging case for my LG Bluetooth earbuds claims to sterilize them; and there's a blue light that appears momentarily when you open it. Might be more valuable than doing your whole phone. If it actually does anything, of course.
Not surprised by the complexity, software and hardware with any medical aspect need to certified as medical devices so I guess only serious companies can produce these.
Let's say I went to the thrift store on Tuesday last week to pick some thing up for somebody I saw one of those there and declined getting it a week later TH-cam recommends me this video I am slightly scared. Although I did bring it upon myself for subscribing.
Nifty device 😮
Do plastic devices survive repeated exposure to UVC? If the steriliser actually works, oxidizing viruses and bacteria, destroying the, then one might expect the device to damage the surface of plastic items exposed.
Can this be used as a tanning bed for my pet rocks?
How or maybe why did you change your work top surface appearance? That was such a "trademark". Initially I thought that it was just a hols location change. Now I am not sure. Nice work though. Thanks for the insight.
This video (plus the last few) were recorded whilst he was travelling due to work
Work accommodation.
Just a thought: With the high energy of UVC, I wonder how a phone's plastic bits, cameras, and parts would handle it?
It's very low power and will be blocked by the screen glass.
Gritty stuff !
"Fumblesome "- 1.bunglesome
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80. ambilevous. Perhaps some alternatives for future use . My favourites No.'s 7, 16, 22, 48, 49 57, 59, 77, 78 😏
Summer, you're the reason why we all got pinkeye because you won't stop texting on the toilet.
Yep, that's what these are for 🤣
Could you do a video on a hall effect sensor
Is it strong enough to produce ozone when you open it right after operating?
No. Wrong wavelength for ozone.
Thanks
Thanks. Much appreciated.
That battey Has got to do a lot for 500mah, I thought a 1000mah would have been a better choice
What on this muddled planet is a decimal value resistor? Decade (decadent?) values perhaps? Oh, I knew I should have taken Latin, even if it's now largely (bigclive?) considered a dead language, R.I.P.
What about putting a UV diode in a computer mouse? When you move it around it sterilizes the desk?
Clive, on the topic of these, I've got a "talking" uvc phone sterilizer with "essential oil diffuser" built in. I think you would really enjoy having a laugh at it. I'd love to mail it to you, how do I go about doing that? I sent an email a few months ago but haven't heard back.
Depending on where you are it may be easier for me to buy one online if you have some keywords.
Why is there even a pcb ?
Mine is an open box that you put out in Sun for a few minutes...
wonder what damage the uvc does to oled and lcd panels
It will be blocked by their outer glass.
Just in time for 2nd lockdowns.
I wonder what longterm use of this will do to oled screens in phones.
The glass should block the UVC.
@@BigClive you're right I didn't think about that
the newer folding phones might not do so well though
hhhmmm... better than expected!
Sterilise a phone that way? Silly, well... I have ocd so, usually I'll put some spray bleach on a bit of kitchen towel and give it a rub over, so long as you don't go crazy, it's fine - people put their phones everywhere, restaurant tables, the floor their pocket, they by their head while they sleep, and people wonder why they're always getting sick 😂
Just checked Amazon, think they have the price wrong it shows it on sale at £5.80
They're selling them off in bulk.
The deconstructive cubes are real tho
These things appear second have for a good price these days. Do they work to erase EPROMs ? If so then they're actually useful.
Not sure if the wavelength is ideal for EPROM erasing.
@@BigClive That's what I was wondering. I'd have to buy one to find out, and I guess they're probably not all alike anyway.
I've a tube of 27128s here that have been waiting for over thirty years for me to do something with them. If I ever do get around to it I suppose I'll have to rely on the lash-up eraser using a foot long UV tube in a box still being in working order.
Sterilising your phone is very important. As the Golgafrinchans found out, you can catch really nasty diseases from them.
HoMedics, a Michigan Company!
Pride of Commerce Township!
Neh. Everyone went earth earth then carved out a slice of the earth pie
What WOULD you suggest for sterilising phones and other similar electronic?
I could be wrong, but my interpretation/impression of what Clive said was more like why would anybody want to sterilise their smartphones.
I use a lens cleaning wipe that is pre-soaked in isopropyl alcohol to wipe my screen for cleaning it. It will have a sterilising effect too.
@@BigClive Thank you for the reply.
I have been doing the same, but had a bad experience with isopropyl stripping a paint/surface finish from some plastics.
So I was looking for an alternative in cases where water can't be used either.
@@galaxya40s95 Isopropyl alcohol is actually very plastic friendly. Are you sure it wasn't acetone? As that is very aggressive to plastics and paint.
Maybe it can erase EPROM's as well ?
Probably not the ideal wavelength for that.
A fleeting bout of dyslexia made me ponder why the big man was doing a video on a Homicidal Sterilisation unit.
One flew over the cuckoo's nest sprang to mind .
Where can I find one to buy??
eBay for around £5
Can you use it to erase PROMs?
Not ideal the 254nm wavelength is better for that.
EPROM eraser?
Do these UVC sterilisers make plastics like phones brittle?
Its UV light so yes.
But it will take time
Ageing the plastic is not a good idea. @@NinoJoel
Will it erase EPROMs?
Probably not the ideal wavelength for that.
Ah Clive, more well made landfill.
This mobile device could be really useful if capable to sterilize hypodermic needles.