Reverse engineering of shady lithium button cell charger.
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- čas přidán 19. 04. 2018
- This video wasn't originally intended to be about the charger, but when it turned out that it was overcharging the cells it had to be explored. Note that ordinary CR2032 cells should not be charged. LIR2032 cells are rechargeable.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
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This also keeps the channel independent of CZcams's advertising algorithms allowing it to be a bit more dangerous and naughty. - Věda a technologie
32:04 There is absolutely no need for you to apologize for a long video Clive. We watch your videos coz we appreciate your expertise and above all we value you. For me one of your videos can't be too long at all and I think that I speak for countless others who also watch your channel regularly. Thx for your great work and for your unbeatable Scottish humor and accent 😃
I once reflowed a pcb with a heatgun and forgot there was a lithium 2032 soldered on the board.
A search for clean underwear ensued. In fact I did a quick check to ensure nothing had embedded in my face.
Avoid touching the insulating ring on the cells. Depositing even a little bit of sweat into the groove will cause the cell to discharge over time, sometimes reducing the life of the cell quite a bit.
"I really like this charger in the sense that it's got this terrible flaw..." lol that's Big Clive for you
I love how 99% of the time I stumble back onto these videos, I learn something.
We never stop learning. :)
Well yeah, the best lesson is: Do not buy the cheapest chinese stuff, if you ain't wana be electrocuted.
Come for the "disappears in a puff of copper with an ear shattering explosion", stay for the "keep in mind this is primary school, what we'd just made was a maraca full of broken glass"
Doug Barry you forgot the “forcefully insert this wire into this probe in a noncompliant manner”.
Watching Clive with the auto-generated subtitles turned on is a lot of fun. "A modest amount of current cloud flow between them" becomes "Amorous Americans could flow between them". Anyway, another great video from Clive!
Mate; don't apologise for the video being long.... we're subbed to you because we like watching you doing this stuff.... long == more... and more is better ;)
Exactly! I was going to write the same basic comment. Love the long videos!
True, but this is Clive we're talking about... This is a man with a voice so smooth I would happily listen to him reading the phone book ;).... Walking ASMR
The only person who thinks long videos are a problem are the CZcams overlords
@@mortoopz You NAILED it, Mort! Even the dictionary, or, dare I say it? The Encyclopedia Britannica. ALL the Volumes. When you wake up, you will know (almost) everything. I am addicted to Clive.
"El Duderino, if, you know, you're not into the whole brevity thing." (via en.wikiquote.org/wiki/The_Big_Lebowski )
Clive, I can remember making the same glass filled maraca's at Woodburn Primary when I was about 8 years old!
I used to be able to recharge any coin cell with those old Bedini circuits. For whatever reason the low current flyback spikes did wonders for them. If I recall driving the circuit from an AA was well suited and even the little 1.5v button cells would recharge to 1.6v or higher. Given the number that could be recharged with one AA it wasn't all that bad a conversion.
45 Minutes of pure Big Clive? Dayum!
Elizabeth Long become a Patron and you'll get em early.
At 22:52 - "Fresh, juicy, lead-based solder" - Video is a winner!
lets not forget "Always use lead solder at home...." I'm a LARGE believer in lead solder... no reason it had to be limited in the way it is.... stupid hippies lol
I train an eleectronics engineer in early 80's so lived the whole ride from basic components to IC's
Love watching you get back to basics ,
!
That was a great era in electronics. The electronic revolution.
For a fun drinking game, go through all his videos and whenever he says "I'm not a 100% sure..." take a shot. You'll be drunk by video two.
I'm good, I don't want the liver failure XD
Chinese circuit designers need to run their projects by Big Clive before production. For a fee of course. ( + massive box of random 'lectronic products)
Wim Widdershins honestly they are really bad.
Wim Widdershins The designer of this model seems very competent. I wonder if she had a reason to actually want the continued charging at 0.1C above the target voltage. Maybe the originally intended cells would self-discharge at higher voltage, causing the charge to level off safely at (example) 4.4V. This might be typical behavior for cells intended as backup batteries in clocks and PCs, designed to be charged in 12 hours and remain stable using just a 2K2 resistor and a diode.
@@johnfrancisdoe1563 That hypothesis would only make sense if the charging circuit was supposed to be *in* a clock or PC, and was charging e.g. 3x series NiCD cells; because Li-Ion shouldn't generally go above 4.25V, and mains-powered clocks and PCs should themselves charge anything that needs recharging.
Meanwhile, almost all clocks and PCs use primary cells; typically 9V PP3 for clocks, CR2032 for PCs, because that's "lifetime" for consumer products (despite we electronics mavens might demand / expect longer) and adding rechargeables adds $$ which most consumers won't pay.
Clive, would you consider taking a couple 2032 cells to pieces to show us the difference between the rechargeable and non-rechargable cells?
Possible alcohol and explosion containment pie dish overcharging of coin cell(s) too? :3
yea yea lets do it clive buddy !!
Yeah! That would be epic
I have a defunct rechargeable emergency light/motion detector light (from Aldi, but rebadged versions were available from elsewhere). After about a year it started coming on randomly and didn't retain any charge.
So I repaired it using cheap Chinesium rechargeables from fleaBay. They lasted about a month before random operation and the case (of the light) started bulging. Opened it up and one of the cells had disassembled itself, forcing the outer case open (and that forced the case of the light to bulge). Inside was what reminded me of the old polyester film capacitors. It took maybe only half the volume of the case. I didn't bother unpeeling it because I didn't want to let the flames out.
My guess is Clive would find something similar inside either type, the differences being down to battery chemistry and not visually apparent.
I could be wrong but I believe there is little physical difference. The differences are in the chemicals used, or so I have been led to believe. Take it with a pinch of salt though as my source has been known to be wrong before.
4:00 "... otherwise, it may go BANG. And while that's amusing, it's not terribly productive for the video." - I am not sure exactly why, but that phrase made me chuckle over and over again, maybe because of the way it was said so softly and easily as a matter of course. Could be that I'm just tired after a long day of working, but it sure hit me at the right time. Thanks for giving me something to smile and chuckle over.
This one reminded me to check the expiration date on the 9V battery in my Fluke 8020A multimeter. It was 8 years past the date - replaced. The Rayovac alkaline still worked, no leaks.
Thank you. I have had a rash of Duracell in date leakers to clean up in the last year.
That multimeter is so good, due to my job I have to test it once every 6months and it's mindblowing how accurate it can be despite its age
Clive, I wish I'd had someone like you tutoring me back in the day when I was a lowly electricians mate.....gave it all up to be a paint sprayer, and then a black cab driver, really wish I'd stuck with the electrician apprenticeship....... But thanks for reigniting that passion I had for tinkering with electronics with fantastic videos like this.
I am only just catching up on all your videos. No need to apologise for the length of the videos. They are interesting and there's plenty of content. I often watch your videos and don't realise how long I have been watching.
For this style of content, you are up there with the best.
I'm always amazed by his hand dexterity when he solders something
My dad owned a hardware store when I was a kid, and he'd supply brand new light bulbs in the bon bon-style packaging to our school every year. This allowed is to fully encapsulate the light bulb with papier mache before the teacher smacked it with a hammer, creating our maracas :)
Also, what happened to capacitive jump starters? I think I'm seeing fewer and fewer of them available.
16:55 This is right out of my Higher Physics Analogue Electronics unit, thirty-two years back. The op-amp has no feedback resistor, so it's switching straight from the negative supply to the positive supply voltage, whatever that is, depending on the difference between the two inputs. The word you are expected to reproduce in the exam is "comparator".
You do get specific comparators. In this case the transition is only "snap action" on the LED flasher with the feedback shifting the voltage divider. The op amp controlling the charging made quite a slow transition between low to high as the battery voltage neared the threshold.
The apparent gradual transition would be due to the op-amp thrashing about as the inputs were very close in voltage. It is effectively pulse-width modulation, and would look quite horrible if viewed with an oscilloscope. However, it does seem to satisfy the "good enough" criteria demanded of a commercial product.
Comparators tend to have a touch of hysteresis added internally, otherwise when the two inputs are very close they turn into oscillators due to all sorts of coupling effects. At least that's what I vaguely remember from many decades ago.
It is a bit of a head-scratcher, why they opted to use a standard op-amp instead of a comparator. But considering LM358s cost just under a nickel apiece, and comparators like LM311 cost just _over_ a nickel (in quantity, both according to Octopart), I suppose that extra half-penny expense would've put it over-budget.
I agree with Merlin though: the output would be interesting/a horror show on a 'scope, but it's "good enough," at least for the manufacturer(s). ;)
if they dont have any hysteresis they can produce rf interference depending on switching currents - not good
love going back through these old videos.
I can just imagine the inappropriate shape a light bulb in a tube covered with Papier-mâché would make, then the horror of imagining a bunch of children running around doing the action of shaking them up and down!
This video was a real treat!
I honestly still don't know how or why it turned out so long.
Nothing felt superfluous, and it was a really interesting little circuit.
I still think that resistor was there for control-loop stability; I might go and simulate it tomorrow to prove/disprove it.
Okay, so after simulating the circuit with the closest equivalent models I could find, it does seem like that resistor is being used to stop oscillatory behaviours. Specifically, if the resistor is omitted, then once the battery gets removed after it is fully charged, the transistor will oscillate every time the transformer-switching transistor switches on or off. The oscillations only peak at around 5.5V, and they die out quickly after each switching event; however, this is without modelling all the parasitic elements of the board and the component leads.
It is entirely possible that, for example, the transformer can cause much worse oscillations due to inductively induced currents.
I thought of it as lowering the Q of the primary winding, which would damp the oscillations when the switching transistor turns off. This is just another way of describing what you suggest, really.
Merlin Skinner; Well, mostly, yes... I actually didn't include the primary supply part (with the transformer), in stead just simulating what would happen to the rest of the circuit when fed by a 8.4V DC supply, with 100mV of 30kHz 'switching noise' superimposed.
The reason why I chose to do it this way, was because I have NO idea at all what the core dimentions or the grade of ferrite is, nor do I know how many turns of whichever thickness wire was used (I only know the turns ratio). I don't even really know the switching frequency, but I figured a 30kHz square wave would be enough to excite any high-frequency instabilities.
I do, however, completely agree that the transformer's inductance, together with the transistor's input capacitance, and even the parasitic capacitance of the coil winding and the pcb tracks, would create a very high-q circuit at exactly those high harmonics of the switching waveform. It's just very hard to simulate without any hard numbers.
In the worst case (and with the damping resistor removed), the Q could be high enough to actually cause an avalanche through that poor little transistor!
All in all, I think the best solution would have been to just add a capacitor to make a simple RC snubber network, while still feeding the Zener from the main supply (like Clive did).
I was pretty sure it was there for a reason, as I've seen very similar things before, and I remember being told it was to decrease some sort of peaking (basically a snubbing resistor/cap). Could this have been fixed using a (very small) capacitor in addition to the resistor there? As the cap should fully charge and open circuit at some point?
What's this Q value your talking about, not a term I'm familiar with.
CZcams is constantly telling me I should watch this again, and every time I see the thumbnail, I think it's a 23rd century Type-1 phaser.
As a child we did the papier-mache glass lamp maracas also. Good fun. no one got hurt that I can remember.
Robothut; Yeah, but in those days children weren't inclined to eat the glass... or cut each other with it, for funsies!
MRLT Indeed! Or bam bam eachother in the head like the Flintstones.
Today,in the US,that paper tube would be classified as a weapon.:)
aye and probably harder to get than a gun.
Robothut Probably a recipe printed in a teachers journal or shared at meetings. Lots of these overly specific school activities are spread like that, with or without corporate sponsors.
CR2032 can make a pretty loud bang when they are charged. Bought a cheap RTC module for an arduino project off of Banggood and had it running for about 3 days when I heard a loud pop and couldn't figure out what happened. Went back to do more work on the project and found that there was no longer a battery in the holder and that it had shot across the shelf the project was put on and left a skid mark on my wall behind it. After some further investigation, discovered that the battery was basically in parallel with the incoming power and only a diode to prevent it from back feeding out to the arduino itself. Being new at the time to buying things from Banggood, I had not bothered to check anything on the module and just hooked it to the 5vdc rail of the arduino and pop went the battery.
Now I just run the RTC on the 3.3vdc rail without a battery in the holder and just have to reset the clock every time it losses power.
Enjoyed that. The image of bearded LittleClive running around his primary school with a toilet roll core full of broken glass (singing La Cuacuracha, likely), was worth far more than the price of admission... thanks...
I first noticed the lenght, and then saw this tiny charger. Then realized, this is going to be good! I clicked on the video with no hesitation because Clive never dissapoints with his content, and this Electronic puzzle is no exception. Loved that Maracas bit btw. Cheers
I got a Clive overdose... Time to go watch a couple kitten videos and come down.
The interesting thing about the maracas is that in theory, they would get safer the more you used them... That is, if the paper held up long enough for the glass fragments to polish themselves.
I like these longer videos, they help me relax. Thanks Clive.
Your primary school teacher had you making "Surprise Piñatas."
In the unmodified charging circuit I think they were misguidedly trying to give the circuit some hysteresis: when the battery is fully charged the transistor starts to turns off which reduces the current through the voltage reference reducing the voltage at the negative input turning the transistor "more off". So when the voltage on the battery reaches the fully charged voltage the transistor snaps off. Essentially the loop gain is increased by this positive feedback. As Clive points out the forgot about the current through the 2K charging a fully charged battery
I look through the comments and missed your post as I posted the same thing (a year late!). It was definitely the cheapest, nastiest way they could have provided hysteresis. They maybe could have coupled the op-amp output back to the non-inverting input but it would have needed a diode and a resistor or two; there goes an extra penny on the BOM.
One of those meters started my fascination with DVM's. Found your channel, Joe Smith and Dave Jones. Too lazy to go to the van and get my 87V I used one of these for testing mains 240volt. However the dial was 180 degrees wrong, ohms setting . Bang, sparks, smoke and a new pair of underpants.
Just noticed the "Burn" setting on the Hi-Pot tester.
When is that used?
31:45 - that "file size" limitation probably isn't anything to do with the technical limitations of your camera, most modern file systems can handle very large files, it's done for tax reasons. IIRC, Cameras that can shoot video for longer than 30 minutes are classified as video cameras and are taxed differently to stills cameras, so most camera manufacturers arbitrarily limit the length of video shots to 30 minutes in software.
what an awful stupid thing.
Governments are involved.
I had no idea about this, now I have a smarmy comment I can say to people with DSLRs! Also, it's quite interesting in general. Many thanks! :D
FAT32 doesn't allow large files than 4 294 967 295 bytes which is less than a DVD. But ordinary DVDs aren't full HD, so 30ish minutes is not an unreasonable limit for FAT32 which the camera probably uses.
He’s doing it with an iPad 2.
Ahh the broken glass maracas :) we made those too in Austrian primary school a good 30 years ago. If I remember correctly we put the paper mache directly around the lightbulb, without the toilet paper core. Good times!
Mum made some maracas for us like that, too, in the 1970s. And she was a English teacher. I'd never have gotten into electronics in the modern risk-adverse era. At high school we made power supplies for the future electronic science classes to be 240v ac mains in, 5 and 12 volts dc out. And breadboard kits
Don't worry about the video being long big Clive.
We love your long videos!
I love these reverse engineering vids. Also this vid was not too long. It's good to get the odd few this length every now and then. That said your best vid is still "Fanny Flambau". Showed that to a friend a couple of weeks ago and she laughed so much she got a small muscle tear between the ribs.
Haha, the maracas at school story made me chuckle. Incredible what teachers got away with back in the 70s/80s. Enjoyed this teardown
VERY nice....
Perfect length.
Long enough to explore all the relevant rabbit holes.
A super-massive 45 minute BigClive video! Hell's Yeah!
I quite enjoyed that too. Until it ended! Clive, Thank You. You are the first person I have seen dissect a transformer.
You might like glasslinger, and also Mr Carlson's Lab; they do restores which sometimes-often involve un-potting and re-winding transformers.
Try Mr Carlsons Lab, depotting a transformer
I think that charger had a fair number more parts than it really needed to have.
On the primary side:
The designer seemed to worry about the transistor not switching in a quasi-random chaotic matter. There is no good reason to not have the roughly 8V on the output side go between 6V and 10V.
On the secondary side:
Making the reference 4.2V would mean no need to power a voltage divider from the cell.
The op-amp's input could go directly to the battery or through a series resistor just to be safe. The output of the op-amp could charge the battery through a diode if you select one that doesn't produce too much short circuit current.
Also. Yes very long video, but it was worth every second. I just want more long videos.
28:45 "It is not ideal that you have to do that" Excellent!
Been missing your transformer tear-downs, Clive! Thanks for that. :-) They missed a trick with using two resistors instead of one, and ending up with a product that could have been made better, and more cheaply. It's a minor shame about not having a reverse discharge diode, but that could have been done very simply, and with a similar component count to this version. Even so, most people would remove the cells when charging had finished, so they might not encounter a problem with it.
I like the longer videos. Now to have one with you and your brother sampling snacks and drinks.
I have found that all button cells are rechargeable and have this handy feature that lets you know they are beyond their usable life by exploding on the charger. Phenomenal! What will they come out with next!
oh, the TP and light bulb maraca was a thing i also made during primary school. you got me to remember that time.
I think your mod bypassed the current limiting that was measured across the 150 ohm resistor.
If the batteries were flat it would of overcharged.
Really interesting, educational - amazing what you dig up, eh? I enjoyed it, but please don't apologize for "too long" videos because my preteen daughter and I find you fascinating and that's why I'm such a grateful subbie! 😊 -Wendi
Well now I had no clue they had rechargible button cell batteries now I know.
Goes off to see if Amazon has some. xD
This is absolutely delightful. Thank you kind Sir.
That 68k resistor will indeed act as a snubber. However the losses will be greater than the RCD circuit normally used.
Those little sealed light units are very useful to keep in luggage, and are a very useful signal light (if you are into remote area back-packing).Clearly visible for over a kilometer.
You can't see those lights from 20 feet away. You're not signaling anyone, besides the person sharing your tent, with those.
I had some similar rechargeable button cells Russian ones I made a slight miscalculation in the current charging and the Cells went into orbit with a big bang !
My favorite head torch in the nite core nu32. Have and it's been going storng for about three years now.
Clive, how does that little charger handle a dead short across the battery contacts? I ask because kids will stick coins in there and plug it in. Hell--I'm an adult and *I* want to stick coins in there and plug it in.
My guess is that the mod Clive did, traded short-circuit protection for over-charge protection.
Not that we would know, now... (as #5 would have said: no disassemble.)
Richard Rudek I don't think so. To get the opamp to turn off, reverse polarity is needed.
Richard Rudek "No dissasemble" Was that a Johnny 5 reference? That's a good movie. Watching it now... Cheers
it will handle it safely, as theres a 150 ohm resistor in series with the battery connection,,,however, if one battery hole is shorted while theres a battery in the other one, that could be nasty..! to make it safer you could fit something like a 10 ohm in series with one line of each battery socket, it'd still flatten the battery with a short on the other socket, but will stop(hopefully) battery blow up..
The Devil In The Circuit thanks that would never have occurred to me. Lol
Clive, there is one thing that has to be said about these crappy chargers. They do have useful battery charging stages, that can be utilised with far better microprocessor controlled chargers. iSDT smart chargers are an example. "I'm Really Crap At Surface Mount Soldering" - It doesn't help when you have a soldering iron tip the size of your elbow, Clive.
Do you not know how to edit a comment? You posted the same comment twice, with this one having extra added to it.
“Mommy mommy! Timmy is hitting me again with his glass filled maraca!”
Oh, the things we miss from childhood…;)
Glad I got to listen to part of this video while in sleep paralysis because I left autoplay on
Excellent video! I think you would find SMT soldering a lot easier if you mechanically held the PCB with a vise or such.
A helping hands
"Doesn't stop charging". This is purely an academic question, but can you explain? If the cell it at it's rated charge voltage, how COULD it continue charging if it is only being given the same voltage? You mean effectively trickle charging the cells as they naturally slowly self discharge? Why is that a bad thing?
You can't keep trickle charging a lithium cell. It causes the lithium to concentrate to the point it causes chemical damage with a risk of sudden failure. With NiMh cells you can keep trickle charging them because they recombine the gases forming on the electrodes back into electrolyte. With lead acid batteries continuous trickle charging depletes the electrolyte by venting it as gas.
I actually like these longer videos.
I love the moments when you take me back when you and I were 10 or 11,we are only a few months different in age , me Nov 64, things were very different weren't they ....
Cool widget. I used to use the LM339 for similar circuits. Cheap and reliable. Wide supply tolerance. I wonder how widely it's used these days. I still have a couple of tubes full of them out in the garage. :-)
Just plug..clup a couple of cells in. Thats why I like unedited videos Clive like yours. Real and as-is. Oh yeah, sorry to hear about your mum from previous video. Hope you and family are doing ok.
Love the story about your primary school days , a time when there was some sanity in the world and common sense was common
Exploding coin cells (safely contained in a pie tin) would make an excellent video.
Yes, the Explosion Containment Pie Dish would be a good host for battery explosions.
David Coghill He already did a demonstration with "car emergency starter" batteries. Much more fun. Though we still lack a demo of non-rechargable lithium cell overcharging.
I misread this as "safely contained in a tie pin"; sounded like a mini-Claymore, "FRONT TOWARDS ENEMY" ;-)
Watching this at 4:30 am, that good is the video, subscribed
i really enjoyed your vid but the smashed glass maraca's story was just like my school..
Brilliant.!
We made broken glass maracas in elementary school too 😂😂 kids these days will never know the things we thought were fun...
Y'know, as cheap as chips, but not as shabby as you might have thought. I'd be proud ofthat as aproduct engineer. The R mod seems odd, maybe the float was to re-vivefy a totally brown bread cell.
oh my goodness, finally, an op amp! I mostly work with analog electronics (mostly synthesis) so it's neat to occasionally see something that isn't logic level
The LM358 frequently pops up in Chinese products.
@@bigclivedotcom I almost want to buy some just to collect discrete parts, but the story isn't worth the large price difference
I think, there could be a reason for the connection of the 2.2k resistor like that. This way the charge current is reduced for very low cell voltages of deeply discharged cells. Some kind of precondition current.
I think the best solution is to increase the 2k resistor in parallel to the transistor to something in the range of 4.7 to 10. For an end of charge voltage of 4.2v and a supply of 8V I calculate a value of 5.2k. Then the resiitors and the 2.5V reference give exactly 4.2V and the trickle charge current should be net zero.
trusting a thin bit of tape of unknown quality for barrier isolation is not good
Uses a screwdriver as a pointer on the schematic... Clive is a god!!
Hi Clive when I was at Nursery dacj in the say we was given a wooden hammer to brake up a piano lol
I'll bet you 2 hotdogs that if I took the same crap you did, I would be able to learn and perfect this craft that you do.
We made the same sort of maracas out of very large 300w incandescent bulbs when I was in elementary school in the 80’s. They were great fun!
I now want a glass-filled paper-mache maracca.
Thomas Galea make one. Instructions are on the internet. It’s fun to do with those vase marbles.
Its really kool that you use the M-830B meter..
I see Op amps so much on GreatScott's channel but it feels weird seeing them in a Big Clive circuit diagram.
Bet they use the 2 tape colors in the transformers to help visually identify which lots had which windings installed at the factory. You look at a tray and you see what's in it.
A car..... a dog “bit” of a different there, I love this guy and that bread rocks
Andrew Horton not if you Spoonerize "dog collar" to " car collad" [a double spoonerization] and abort half way through. 👍😊
Not massive difference... Dogs have 4 legs. Cars have 4 legs. Dogs can be raced on a track. Cars can too. Basically the same animals.
tin2001 I love your logic
They also make lots of noise, pollution, and slobber too. XD
Rechargeable button cells - did not know they existed - thank you for that. Though the aspect of mains charger that charges two - does seems a bit mad in many respects - solar charge be nice as they won't need much juice and would make more sense. Mains power for something so small just seems like the wasted energy from mains conversion would exceed what you would charge the battery with.
With that it feels like akin to feeding an ant with a steak.
22:24 brute force and ignorance, two of my favorites!
a LM358 with an adjustable current shunt...
Hey look they added a green laser pointer driver to it!
got the same item from alibaba express for $2 it s a cool one. just wired in a USA plug since it came with EU one. for any consumer battery you can recharge them. the worst that can happen is they pop open with the button cell and a little black power falls out. if the "disposable" battery can be recharged it will hold a voltage after unplugging it from the charger for 30 minutes. expect for Lipo and Li Ion batteries recharging is safe. Lipo typically will go flat down to zero and cant be recovered. 18650 battery have a safety value that has to be reset by pushing down to bring a battery up slowly. best to charge batteries up with 500ma or less from a low voltage. after charging batteries i stick them individually in clear bags to protect against possible leaking.
Simple trick to comparators. When the input equation is true the output is high. When the input equation id false the output is low. Works for opamps as well.
Your videos are awesome man. Smart fellow
I wonder if the design has been taken from an old product, hence the lack of specialised chips with discreet components, and repurposed using SMD?
I love your light bulb maracas story and I'll be passing the idea on to my sister-in-law, who runs a childrens nursery - she'll be thrilled!
It certainly had a lot of parts for a cheap design. It makes me wonder if it was really cost optimized. Even cheap parts have a cost to obtain and place. Sometimes spending a bit more on a purpose built IC is the way to go.
Quality video with a quality anecdote XD
I had a frisbee/ultimate disc that would use this same mechanism to turn on a light in the center of the...disc. Was great for once the sun starts going down and you want to keep playing, even just a little light from a flying object is enough for human eyes to track. Same waterproof 'tighten to turn on' setup.
That broken glass maraca story is ringing some bells. I think I did the same thing in elementary school.
I bought one of those chargers with a tray of those cells for those same lights for my cats at night! Never worked a dam (charger not lights, lights were good)