I've never in my life had any talent for physics and I have a degree only in software development, but I've gotten crazy invested in electronics (got a whole soldering station with all the required tools and knick knacks, INCLUDING A SPUDGER!!) thanks to your videos. They are very educational and keeps you watching, no matter the subject. Please never stop making em for us big clive!❤
A slightly longer version, with a few more rows of LEDs is also available. They come in two variants, the most common being a 4.2v sealed lead acid battery. The second variant has two 18650s in parallel. The circuit uses the same components.
Every family has several emergency lights if you're in a country with frequent blackouts. I got to know them from Brazil more than 20 years ago. But they had small fluorescent tubes in it back then. They were everywhere - in hairdressers, supermarkets, stores, shopping-centers, garages...
South Africa the same, it is still odd that I have still had power on all the time for the last 212 days, when before you woulds have power cut almost every day, since 2008.
The charging circuit is a simple series voltage regulator. These were very common before the integrated regulators became readily available. I built many series regulators myself back in the 1970's when battery eliminators were linear and unregulated. The unregulated supplies used a transformer, a diode bridge, a capacitor or two, and a couple resistors. The transformer would hold the voltage sorta close, but the AC ripple would be unacceptable for transistor radios no matter how big a capacitor you added. A better idea was to buy or build a higher voltage supply and regulate it down to the desired voltage using a series regulator. The series regulator would conveniently lower the ripple sufficiently for most applications.
I remember the emergency lights in my old elementary school back in the 80's, they were the size of a small microwave oven, took a car battery, and had PAR36 lamps! Talk about robust! We've come a long way since then.
I'll take a dozen at that price!!! Genius level design on the housing doubling as the battery holder. Running on 110, the only thing I would change is battery capacity! More than likely, I'd leave it alone and put one in every room... Love it 👍🏻
$3 is absolutely amazing for this regardless of circuitry how much was shipping I love it when you buy something for $3 and they charge you eight bucks to ship it I'm amazed that It has a replaceable battery
I don't think I'm far wrong in saying that Chinese engineers are masters at creating or finding the cheapest solutions possible. The problem is that sometimes they cut too many corners and end up in the dangerous zone. (in electronics, mechanics, chemistry.... everywhere) That's why we need people like you to take a look at "what's inside"....... before we end up in an inferno of flames, acid and shrapnel.
I think the 4.7 volt zener has a temperature coefficient that means as it gets hotter the voltage drops, same as the VBE of the regulator ..so that whole circuit may actually be very cleverly temperature compensated as well.
I built an emergency light before myself. I made the circuit with the Software "circuit" by Paul Falstad. I connected 14 one F Capacitors together, and you could charge them with a small hand powered generator. 30 seconds of charging is enough to power a white LED for about 8 hours before it gets dimmer. The capacitors are not anywhere close to full after 30 seconds so it has more potential. I was annoyed by these cheap hand powered flashlights that perform really poorly and wont work when you really need them.
I might get a few of these for my basement, but modify them for 12V DC power as I don't want to run mains cables to the various locations. Maybe I'll use an LM317. If the 500mAh batteries don't last long enough, then I can make the lights dumb and the 12V DC can be on battery backup and handle the cut over on power failure/test.
I'm wondering if using a 5V USB supply on the DC side of the rectifier and maybe getting rid of the 1K resistor next to it may be an efficient option. My choice of power failure lights is still a head worn light and the classic PIR ceiling lights that will kick in when needed.
No need to even use a LM317, just remove the 680n capacitor, and replace with a 220R 0.5W resistor, and it will operate exactly the same as before on 12VDC or AC. Battery the same, or replace with a pouch cell, though this cell likely will provide output for around 5 hours on dim setting, slowly fading as the battery discharges, so it will still glow after a day with power off.
If you want to check capacity of batteries like this then get an XTAR VC8 Plus battery charger. The first 4 of the battery compartments can run a 'Grade' battery checker, which does a charge-discharge-recharge and calculates the mAh's.
BMS stands for 'Battery Management System' this product does not contain a battery and therefore does not need a BMS, This is a single 'cell' stop with the 'Look at me everybody I know stuff look at me'
@@andymouse Sounds like you should be telling this to yourself cause that actually is a lithium ion battery and they DO need a bms cause when lithium batteries get mistreated they can blow up or catch fire and thus need a battery management system. Also the fact that your logic is "battery management system means bms so it is only needed for a battery" is totally wrong! Its like saying you cant fry an egg cause its a frying pan and egg does not have the word fried in it. Unless this is ragebait i will take my comment away but please dont go saying "oh look its another person who thinks he knows stuff 🤓🤓🤓"
@@andymouse Untrue. A "battery" can be a single cell and that single cell should still have protection against overcharge, overdischarge, and current limiting, except that in this case, the circuit itself inherently does this, unless it fails. The one thing it doesn't need, being a single cell battery, is cell balancing. In fact, some single cell batteries do have a BMS built in and then it's called a protected cell. As far as the look at me comment, you should feel embarrassed.
The 1k resistor isn't stressed at all. The voltage across it is limited by the 5.6 volt zener and its 10 ohm series resistor which are in parallel with it. You measured about 50mA from the mains, and most of that goes into the battery while charging, and into the 5.6v zener and 10 ohm resistor when it's full. The current through the 1k will only be around 6mA at the most.
Zener voltage very easy to drop the voltage, simply increase the resistor from the supply to base from 330R to something higher, probably 470R to 1K, which will probably, because the zener diode at 4V7 is a rather soft breakdown, so the slope resistance works for you. I did the same to older NiCd lamps, using some selected 1W zener diodes, running them at 50mA, and then using a multimeter to bin them for voltage drop, selecting from the packs of 10 2V7, 3V0, 3V3, 3v6 zener diodes, plus a pack of 1N4007 diodes, so as to get a way to have them sit at 4V2 for the charge voltage when the battery was disconnected, so as to cut the charge to zero, and not have a constant 50mA flowing through the cells, which was killing them every 6 months. As they were 1W units, a small bit of metal soldered to the leads (old spade terminals from PCB connections as I had lots) was added as heatsink, and then the diodes with selected series strings were fitted to the board, and the new cells soldered in. They lasted at least 2 years then, making it possible to actually have the emergency lights work when power went out. Same was done to later cheap lamps, with 3 cell lead acid packs, as they also would suffer from cooking the cells, even after dropping charge current down by removing the one resistor of the parallel pair of 0.25W resistors dropping the voltage from the small 6VAC transformer. they also introduced me to a retrofit SMPS, built to fit in place of that small cheap transformer, with a simple half wave rectifier and mystery input capacitor, 2 transistor blocking oscillator, and rectified flyback secondary with primary side regulation, and a 100uF 16V capacitor, possibly made almost entirely from recycled components. Came with 2 wires primary, 2 wires secondary, and still had a bridge rectifier on the main board. Bet the next run the removed 4 diodes, and soldered the wires direct, saving that 4c from the BOM.
With that big of a box you'd think there would be at least 3 batteries! I have one of those black box solar lights, I had to change the battery twice in it, now I put two 18650 in parallel hope they will last more!
I managed to stuff 8 of them into a solar light, replacing the 2 dead EV lithium cells they had in there. Also had to replace the BMS as the venting cells had corroded the protection board in the shrink wrap on the cells. DW01 board, 8 recycled lithium 19650 cells, and a new glass front ( because it was stuck in with silicone) glued in place, and it has been working well for a year now. Took a week to get fully charged, and still runs the entire night at full power, even in winter.
Who doesn't like Aliexpress stuff ! I do, they always have funny things for cheap, I always order many stuff every month for around 100 euro, just for the fun of it ! And a lot of stuff is really useful !
We've got three that look like a higher quality version of that, came with certification for use as an emergency light and 220V plug. They were more than $3 but not a lot, I think maybe $5. Ours have 18650 batteries.
Li-ion at end of charge - must have the 4.2 Volt removed. Unlike PbSO4 batteries, they degrade very quickly if the charging voltage is not removed at end of charge.
Be careful! This charging circuit doesn't meet the charging requirements of standard lithium cells. When the voltage reaches 4.2 V and the charging current reaches an average of 0.1 of the initial value, charging should stop completely, otherwise a slow degradation of the battery electrodes occurs with the risk of short circuit over time. This emergency light itself will eventually cause an emergency. It's quite ironic.
I cant speak for all zenners but the ones that I used to design with had a voltage specified at 1mA for the 250mW and 500mW parts and 10mA for the 3W ones.
I bought some emergency lights 3 years ago but this one for only 3 dollars has better features with a button you can turn off the light. We get the odd power cut and they are brilliant just come on and my one runs for 3 hours.
That's why any cheap battery powered electronics never lasted. They intentionally let it overdischarge so you buy again. I had a cheap bluetooth speaker that lasted for a month, with the battery fully filled with hot glue in the case so it's pain to replace it. I surrender and tossed it to the bin.. Got a trauma from it, i don't buy battery powered electronics anymore..
Shunting the capacitive or resistive dropper is massively easier than trying to shut the power off. The designs that try to do it the "proper" way are very complex and expensive compared to the simple shunt.
A month ago I went to Romania, it was full of these emergency lights, the power went out, none of them turned on... I don't trust them, I prefer the Legrand brand emergency lights, they work the best.
...Ah...it's the simple things...Thanks for that....Hopefully the white solder mask didn't make tracing too hard...Single sided would have helped...clever.
I bought an emergency led thing off aliexpress a few years ago, had the usual figure 8 plug input, worked one way, but when I plugged it in the other way it blew up
Not entirely sure I'd trust such a thing myself, just seems a bit too squirmy for my liking, I have visions in my head of that solar light from a few years back that had an 18650 ejecting out the side from being overcharged....... :S
May be 'not bad circuitry' but not a very safe device, if it falls it can open easily showing the inside high voltage parts, neither strian relief of the powercord... Must be another quality - high safety device from good old China! to overflow our market with...
I'm amazed there aren't more zener+junction-drop charging circuits. I guess you do have to make sure the input is current-limited, but at 500mA, most lithium cells will cope with that just fine, and it'll drop as the battery gets closer to full. Much simpler than a full BMS. Cheaper? Dunno, charging chips are jellybeans these days anyway.
You may want to look closer to home for examples of deskilling, forced labour and exploitation. It's everywhere. I get the feeling that it's weaponised against some companies for business reasons.
I wonder why they've done it that way... Dedicated charge controller chips are very cheap these days. But this is definitely a valid way to limit the voltage, and could be used in a DIY project.
Although, if the zener 4.7V zener diode fails open circuit, it could overcharge the cell. But zener diodes generally fail short circuit, and there won't be enough current to blow it open.
I was just reading about acting props and personas, the best RU-vidrs I know have it all just being themselves, desk, printout, breakdowns, present in their personality just being themselves and what they like doing. ❤ ❤❤❤
