$3 AliExpress 100-240V emergency light (with schematic)

[@humidbeing]

For those that don't know: An emitter follower (sometimes called a series pass transistor) + Zener is the basis for creating linear regulators. This is basic analog circuit design as shown in The Art of Electronics. It only seems genius because basics like this aren't taught to people anymore they jump straight to micro controllers. (I'm talking about the commenters, not Clive, obviously he would know this)

[@VarionJimmy]

I was thinking about the emitter follower. It’s not often you see that nowadays. It felt like I was watching a schematic from a couple of decades ago.

[@trueriver1950]

​​@@VarionJimmy I got a set of spare batteries complete with charger for less than an official battery would have cost for my Galaxy Note (the original Note, which was not actually sold as the Note 1, to give you an idea how long ago this was). The charger had a bright purple bar of LEDs that turned red when the battery was fully charged. In fact, behind the plastic there were two blue LEDs which took current proportional to the charging current, and one red one that took current proportional to the charging voltage. (Or maybe I have the colours of the LEDs the wrong way round, it was a long time ago now. The regulator was just like this circuit here: a zener emitter follower. I cut down the charge voltage to extend the life of the cells by inserting a power diode into the charge circuit, shorted with a switch for when I wanted a full charge: the extra diode dropped around 0.7V for me. It worked great right up to the time when I left the phone on a bus 😢 and stopped using the charger and those batteries And despite my initial doubts the Chinese cells that came with the charger seemed about as good as the official Samsung one that came with it, at least for the 22 months I was using them...

[@wtmayhew]

Emitter follower is in my curriculum when I teach Devices. One of our labs is building an emitter follower to launch pulses into a long 50 Ohm co-ax and monitoring the 50 ohm emitter resistor with an oscilloscope to see how long it takes a pulse to be reflected from an open or short at the distant end. Knowing the velocity factor, the students calculate the cable length. It is a neat way to get a small bit of transmission lines and impedance matching into a Devices class.

[@emolatur]

Glad this comment is already here. The concern I have here is the potential failure mode. For whatever reason, most transistors (at least both bjts and mosfets) have a tendency to fail short... at which point that cell most definitely will be overcharged.

[@sei-core]

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!❤

[@BillDunlop-b1u]

The beauty of this regulator is, a 4V7 zener has a negative tempco almost identical to the b-e junction of a silicon transistor. So the overall tempco is effectively zero; a very stable circuit. It's not often that (non-ideal) component properties work fortuitously. By the way, Y1 base resistor (330R) wouldn't have any effect on the voltage limit at Y1's emitter (within ridiculous limits, of course) if the zener and Y1 are thermally close. WARNING: old man rambling. This is why digital electronics is traditionally run at 5V; the tempco of 5V1 zeners is virtually zero; above that zener tempco is positive, below negative, and the early digital circuitry was very, very fussy. When we had to design (series) regulators, we had to use thermistors (sometimes series/parallel) clipped and glued onto the same heatsink as the transistors and zener. A lot more than $3. MORE rambling: A friend (back in 1970's) who was senior computer tech/programmer/administrator at a very large firm, would start the power supply for the mainframe 1/2 an hour before turning it on. The PSU consisted of two 3-phase motors each driving an ELV alternator through large flywheels, which when up to speed, were switched into the PSU circuits, which were left for 10-20 mins. to stabilise. It was a very warm room, separate from the air-conditioned mainframe room. This had the advantage of having redundancy, great stability and was an effective, if crude, UPS (10 mins running if no peripherals running). Ah, happy Algol/Fortran days. Hope this isn't boring.

[@sjmww1235]

Very interesting about the tempco correspondence. Learned something new today

[@richardwernst]

Very clever way to connect to the battery!

[@gdm2417]

Avoids needing a battery lid! (which always gets lost or broken). Cunning cost-saving.

[@Liz0rdX80]

Very cheapy Chinese mass production stuffs

[@richardwernst]

@@Liz0rdX80 I think the way they did the battery/hold very clever, also makes it easy to upgrade the battery capacity or replace if failed, no soldering, etc.

[@Liz0rdX80]

@@richardwernst yep

[@mikedjames]

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.

[@fuller9x]

So the lithium cell will provide an audible and visible alert when its time to replace it. That's a plus I guess.

[@tenminutetokyo2643]

Looks like a bang up deal for $3.

[@ebradley2357]

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.

[@RedFathom]

it's a sad day when proper circuitry is inspirational...

[@nomusicrc]

$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

[@jagboy69]

Don't you know the chinese govt picks up the tab for shipping??

[@u.e.u.e.]

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...

[@SeanBZA]

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.

[@jimmybrad156]

@@SeanBZA Interesting, I wonder what might have changed in the last 212 days?

[@SeanBZA]

@@jimmybrad156 Lower power demand, plus there has been commercial and residential solar coming on line equal to at least 6 stages of load shedding. Massive numbers of medium power users have gone with either grid tie or fully off grid, with most of the Massmart (Walmart owned) stores all now having solar power as major part of their daily power use. Then lots of home solar and battery banks that are being used to shave peaks.

[@davidg4288]

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.

[@helgew9008]

The Commodore 64 (from 1982 or so) uses a regulator like this for the cassette motor. The early versions used a Darlington pair, while the newer revisions were cheapened to a single transistor.

[@whitelion7976]

I have some emergency exit signs with similar circuitry. Very interesting.

[@edwardfranklin18]

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.

[@chrisfranklin2104]

Greetings, Edward ! Are they available somewhere in Uk?

[@chrisfranklin2104]

Greetings, Edward Franklin ! Are these available anywhere in the Uk ? As the one Clive shows has a USA mains plug 🤔 Cheers

[@CYPH3R-0]

yeah they're lithium 18650's, not a AA

[@the_once-and-future_king.]

I think that's a 14500 protected cell. The little 'collar' is a giveaway.

[@BlondieSL]

Nice catch!

[@bigclivedotcom]

Probably a pressure switch, but no electronic protection.

[@Captain_Char]

better then some of the cheap ones ive seen here, which was basically a capacitor, resistor, and two lead acid cells that got overcharged and swelled up causing the unit to stop working

[@amorphuc]

Wow! Thanks Big Clive. Pretty cool little unit. Thank you so much for your time and bringing this to us.

[@kevtris]

a while back, I reverse engineered an LED exit light with backup power similar to this, but it had an interesting circuit on it that prevented the LEDs lighting until it had power at least once coming in on the AC input. it was all done with 4 transistors, and two of them were set up as a bogo-SCR to latch when it got the AC power. the battery pack kept it latched once triggered, and disconnecting the battery would reset it. this had the side benefit of dropping out when the current through the LEDs went too low, due to the battery discharging.

[@Shaun.Stephens]

Thank you Clive. Even after all these years of watching your videos I still learn the odd bit here and there. :)

[@seanrh4294]

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.

[@Lazmanarus]

1F caps - that's a bloody big capacity.

[@stinkycheese804]

14F worth of capacitors for barely any light for 8 hours? Seems expensive and bulky. Have you ever heard of "batteries"? I can grab my EDC AAA powered pocket flashlight and have light for 8 hours, or a lot more light for 1 hr.

[@seanrh4294]

@@stinkycheese804 I made it for emergency and camping. The capacitors can be charged more to hook up more LEDs and to last longer. 1F Capacitors are not that big (some of them are) and you can get them cheap. I got mine on amazon.(about 50€ total)

[@K26650]

​@@stinkycheese804you can't charge a aaa battery and you can't leave it empty for years and expect it to work. Capacitors seem like a pretty good option for a hand cranked emergency light.

[@bigloudnoise]

I was just today looking for emergency power-failure lights with easily replaceable batteries, then this video pops up. I think I might have to order a few of these!

[@SeanBZA]

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.

[@zebo-the-fat]

Not as bad as I expected!

[@nuNWO]

I love buying things that have "a free bit of plastic" included

[@Ray_of_Light62]

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.

[@bigclivedotcom]

As the full charge state approaches, the current will progressively drop to zero. But I'd rather it charged to a lower voltage like 3.9V.

[@casemodder89]

3.7V is about 50% so the equilibrium of electrons in the positive and negative side of the separator. that gives the max. possible life in a standby application. 3.9 or 4V is best bang for the buck hence older dewalt equipment used this as termination voltage. the problem with the ever dead laptop batteries is exactly the 4.2V termination, keeping it at that and people not removing the battery when they work on-grid. i got a toshiba Netbook @ Win 7 (the tiny 9-10" laptops, better known as the Asus? EEE PC), that's still on it's first battery. from 2015 ! always charge it to 50% then remove the pack when not in off-grid use and it will last AGES. samsung one day inttoduced the battery saver which terminates charging at 85%. and even that does wonders to battery life. like on my galaxy Tab A SM-T585 (also on it's oem battery) and the previous white /silver bezeled Tab A that only serves as a kitchen timer for eggs and stuff. treated right Li-Ion and Li-Po can last a decade. but most devices + users never treat batterys right. being an apple product + the accompanying user makes everything even worse.

[@muzikman2008]

Nice for the consumer unit incase of power failures. 👍

[@GodmanchesterGoblin]

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.

[@sweh]

That can't be a very high capacity battery, 'cos otherwise the battery would be worth more then the whole unit!

[@andyspoo2]

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.

[@stinkycheese804]

@@andyspoo2 No need to get that specific charger. Any better quality Li-Ion charger has a discharge capacity test function.

[@Quickened1]

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 👍🏻

[@KeanM]

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.

[@bigclivedotcom]

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.

[@SeanBZA]

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.

[@stinkycheese804]

Why even bother? I mean you don't need this light at all then, just use a buck switching current regulated LED driver to drop from 12VDC to whatever current your array of LEDs needs. More efficient, or of course you could just swap out the 14500 cell and swap in an 18650 around 3400mAh and it'll run longer than you'd normally need.

[@KeanM]

I design IoT based emergency lights for a living (amongst other things), so the electronics is no problem. LM317 was just a quick idea that others could also use, as I typically use boost or buck LED drivers from Diodes Inc. My interest is the low cost compact housings. They don't need to be compliant with standards for use in my basement workshop.

[@KeanM]

BTW, I ordered some of these lights 3 weeks ago, and got them last week. Getting ahead of the BigClive effect can be important as the price from the store I bought them has now nearly doubled. Still reasonably cheap, but not quite as easy an impulse buy.

[@normandothegreat]

Brilliant in its design. 😊👍

[@stoneostrich129]

Interesting little light. I have a couple of, what I call, "Oh Shit" nightlights that turn into a flashlight in a power failure. That, and a battery bar light magneted to the back of my steel door. Has come in handy a couple of times, thanks to drunk idiots knocking over the power pole with their car.

[@jpkosoltrakul]

I got a very similar looking one sold under local lighting brand in Thailand 6-7 years back. But mine had a separated circuit board and a 18650 cell soldered to the wires from the circuit board. If I remember correctly, funnily on its package or the leaflet said that it should not be plugged in all the time, which defeats its purpose for being an emergency light (I guess because it would keep top up the cell to full charge all the time, which would shorten the cell life). I ignored the warning and left it plugged in. Until maybe half a year or a year later, it was no longer able to charge. The cell still worked and be able to charge with external charger, although the capacity was pretty much gone. The light itself also still turned on with other fully charged cells, it was just the charging part (and the test button) that stop working. I didn't bother try to fix it, so I hooked a 18650 cell tray on its back and use it as a flashlight instead.

[@chuckthetekkie]

Sometimes simople is the best. I may have to get some of these. I like that it's works on both 110 and 240 volt mains. While we don't have too many power outages, I always wanted to have emergancy night lights.

[@electroumit]

Thank you again.

[@Sentinel-1]

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.

[@massimookissed1023]

What's _really_ ironic is the light won't work during the emergency that it caused.

[@gertjanvandermeij4265]

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 !

[@AlaskanInsights]

The danger is real, but so is winning the lottery. I think the odds are about the same in this case.

[@volvo09]

House fire lottery...

[@SeanBZA]

@@volvo09 That mains wire is the fuse.....

[@calex9398]

Inspirational indeed

[@DanielDan-rg9zw]

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!

[@SeanBZA]

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.

[@stinkycheese804]

Not necessarily, they keep heat management easy by using that LED board, then the enclosure has to be as thick as the battery in it. Since it's not meant to be pocket carry, why would it benefit to be much smaller? Besides, 3 batteries would increase the cost.

[@wirdy1]

These types of lights are ideal candidates for some paralelled disposable vape cells that we all seem to collect :)

[@satanicinduction]

Nice simple battery protection That could make using lithium cells in random gadgets slightly less sketchy

[@JoseSilveira-newhandleforYT]

Very interesting! This video comes just when I was considering buying two more emergency lights for my house. If the price doesn't go over the roof after this video, I may even buy more :-)

[@greendragonmakerspace]

Great stuff, Thanks! I'm going to make one of these.

[@Fred2-123]

I just got one for $0.99. Limit 1. ☹ Also got the one you showed the other day "Simple USB LED panel for adding light anywhere", 20 LED version for $1.37. and the 16 LED version for $0.99. Free shipping. Not the new-account-only price, good for returning customers. This has to be a first, the price went DOWN after a bigclive video went up.

[@jamesplotkin4674]

As of my posting, these are going for an astonishingly low $0.99 with free shipping.

[@carlettoburacco9235]

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.

[@phantomkate6]

Hiiiiighway to the danger zone!

[@dcallan812]

$3 for an emergency light 🤔 I wont be rushing to buy one dont want it burning my house down. 🤣 Interesting bit of cr@p 2x👍

[@volvo09]

Yeah, kind of scary to have a $3 device with a lithium cell plugged into mains for years.

[@robertfitzjohn4755]

I recently bought an emergency light from Screwfix for £19.72. I think the battery is Ni-Cd. I was amazed at how many components there were on the circuit board, considering it doesn't have to power a fluorescent tube like the old one did.

[@jarekqwerty6433]

This cell should have protection BMS (maybe it is built into the cell). If it is not there, it is worth adding it.

[@andymouse]

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'

[@309electronics5]

​​​@@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 🤓🤓🤓"

[@stinkycheese804]

@@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.

[@andymouse]

@@stinkycheese804 Not me pal..Goodnight :)

[@davadoff]

A single cell protection circuit board is still called a BMS

[@fishyerik]

Unless it's a high voltage type lithium cell, keeping it charged to 4.17 V most of the time will make it degrade much faster than necessary. A 18650 cell isn't that much more expensive, and will have much more capacity at 4.0 V, or even 3.9 V than that 14500 has at 4.17, and would last many times longer. Could have been a much better product for just a slightly higher manufacturing cost.

[@d.t.4523]

Thank you, keep working.

[@CollectiveSoftware]

It shorts its power supply to test? That's cheeky!

[@zh84]

It's not /quite/ a short, as there are resistors in the circuit.

[@FamilyOfEyles]

I wonder what the supply current goes up to while the Test button isreerssd? Would it damage the bridge or dropping capacitor in any way?

[@Friendroid]

That is not what is known as short.

[@davidg4288]

That avoids high voltage appearing anywhere past the dropping capacitor. It's also a real test.

[@MeriaDuck]

I was wondering why the 20 Ohm resistor was important, the schematic was revealing 😂

[@jeffdayman8183]

It's a neat little light but I don't think the battery connection is a good mechanical design. Depending on the plastic to keep the metal contacts making a good connection is optimistic. The plastic will relax over time (creep) and contact tension will be reduced then lost. Any number of simple springy type contact arrangements acting in the direction of PCB assembly would be far better and much more reliable mechanically. L shaped bits of stainless steel spot welded to the cell ends would be an easy and cheap way to do the battery side mechanical connection reliably. Just my opinion. Cheers!

[@Mr.T4LLY-0]

We like a circuit that makes BC happy or impresses him. Be like (some of) AliExpress 👍

[@gordonlawrence1448]

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.

[@robertburrows6612]

I remember the days when voltage regulator were made using a transistor and a zener diode with a big heatsink

[@Sonny_McMacsson]

The battery charger is just emitter follower thing used in those solar lights you showed in earlier episodes.

[@royshaft]

Neat ! Fit one above a fusebox , just in case ?

[@dpvng.dpvng.]

If this thing had a pir sensor, it would be priceless.

[@SigEpBlue]

And no fuse. Great.

[@BlondieSL]

There should be at least 2. One for the input and one for the zener .

[@joeschmo622]

Nah, that's a standard voltage-follower regulator. Even as a kid I used 5.6V zeners to get a quick'n'dirty 5V supply. Kick it up to a 6.2V zener for power Darlingtons like the TIP41/TIP42 pairs if you want bipolar +/- 5V supplies. You might not be able to wait for the 78xx/79xx regulators if you didn't have the voltages you wanted, but you could keep a supply of zeners in *all* voltages for cheap.

[@nigelwilson8331]

Nobody has ever heard of a spudger till clive used one.just the old kitchen knife was used by many.😅.

[@Shakey31]

Thanks, i got 2 in my cart now lol

[@tonysheerness2427]

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.

[@rj7855]

I've been using that charge circuit for year, it does however has one weak point; the zener, if it breaks the cell will overcharge

[@therealjammit]

Personally I'd replace the zener for the battery with a TL431, with the sense pin hooked up to a resistive divider that's connected to the battery.

[@jerrydurand4127]

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.

[@andyreact]

Neat little light! Is it bright enough to be useful?

[@bigclivedotcom]

In a power outage, anything is helpful. But it's actually quite bright as a work light.

[@stinkycheese804]

Define useful?

[@andyreact]

@@stinkycheese804 most emergency lights only give out enough light to just about see how to get out of the room you're in. I meant is it bright enough to use as a general light for work or whatever...

[@stinkycheese804]

@@andyreact Work or whatever? No. this is going to only produce a few hundred lumens at most, is literally only enough to not bump into things while evacuating the premises in case of a power outage, or to see well enough to find your vastly brighter flashlight.

[@davem4845]

Mmmmm, Kink Palculator!

[@phils4634]

My original comment was strangely deleted by YT! We have a similar model, however ours uses an LiPo flat-pack battery, and a "legit" charging / discharge protection circuit. Bought it back in the day from Bang Good, and it's now very "old and yellow", yet still works fine.

[@phils4634]

You can also buy rechargeable LED lights for installation into standard DIN D rail distribution panels. These are durable, demountable, and a lifesaver in cases of unexpected night-time outages.

[@UKsystems]

you can get standard ones there too i upgrade the lithium cell to make a torch

[@brabhamfreaman166]

0:50 FULL-BEAM; dipped beam; FULL-BEAM; dipped beam; FULL-BEAM; …hours of switching fun😅

[@leybraith3561]

...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.

[@jagboy69]

For 3bucks, you just KNOW this thing is waiting to burn down your house when the power takes a shit.

[@fourtysix4646]

It’s been a while since I’ve seen a good doobie video, maybe some electrocution cooking? I always get the munchies after.

[@bigclivedotcom]

No more electrocution cooking. KZbin is not a safe platform for that any more.

[@ReedmanFL]

Clive, I am suspicious of the brightness control on the far right of your schematic. The diode in the upper right forces its cathode to be one diode drop below the "5.6v power bus". I don't think that voltage can ever be low enough to pull current out of the base of the PNP and turn on the LEDs.

[@ReedmanFL]

Never mind ,,,, I forgot that this light is an emergency light and will only turn-on when the input power is off and the 5.6v bus is dead. My bad ....

[@Z-Ack]

I bought a cheap head shaver, one of the shavers with the 7 little shaving surfaces.. looks like a flower. Well the thing cost me around 9$ shipped and went to use it the other day and it bogged down suddenly and burst into flames.. the entire time it was burning the motor stayed on.. until it was a crispy thing.. would be nice to see one reverse engineered.. i never got to take it apart.

[@bigclivedotcom]

Any keywords for where you bought it from?

[@nevilleaufdermaur]

Nice circuit. Please check the cell capacity, now i'm curious.

[@georgeemanson]

Great video - as usual - Do you have any ideas on how to put a 'over discharge circuit' into the battery line to prevent over discharge?

[@wirdy1]

The little circular bms boards kit or parts that sit atop the battery with a strip to the negative & some heatshrink to tidy the job are fairly cheap on Ali. Haven't looked if they do them for 14500, but certainly for 18650 & would fit even though slightly larger circumference of the pcb, it wouldn't matter in this application.

[@frogz]

surprised they have not made these usb for universal dumping the power supply on somebody else's problem

[@teslatrooper]

I wonder how that charge circuit behaves over temperature, clever solution though.

[@gregorythomas333]

Well that's different! Don't know if I like the way it shorts the power supply though

[@Slikx666]

I'm looking at it and wondering if an 18650 would fit with a small amount of modding? At least it could have a protection circuit built in. 🤔

[@Cassandra_Johnson]

Would that PNP transitor trick be more useful for night lights compared to shunting out the power?

[@bigclivedotcom]

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.

I'd love to see schematic for the E-Bike / Motorcycle / Car lights that are powered by 9 - 80 V DC.

[@bigclivedotcom]

Here ya go... kzbin.info/www/bejne/iWe0n6N-rJxpl6M

[@TomCee53]

I hoped you would check the current draw when testing in low and high brightness.

[@bigclivedotcom]

4.2V = HI-170mA LO-106mA 3.6V = HI-120mA LO-73mA 3.0V = HI-84mA LO-51mA

[@bahagursoy8138]

Dear Sir Nice work. Can you say value of capasitor and resistor for 220V mains. Thank you Stay safe Baha

[@bigclivedotcom]

This is designed for 220V.

[@MothKeeper]

Clive, how about a score out of 100 for each device and/or circuit used?

[@bigclivedotcom]

I've toyed with a scoring system, but safety and longevity are hard to quantify.

[@wirdy1]

Good idea. I'd like that too. Maybe scores out of 10 for Design, Componentry, Efficiency, Value for money & overall.

[@jerrydurand4127]

Holding a lithium battery at that voltage will shorten the life of the battery, same as running it down below 3V.

[@fire_stick]

does the lithium cell have built in protection? to stop discharge

[@bigclivedotcom]

No. But the current is very low by 2.5V.

[@davidfalconer8913]

The charging circuit is worth building to recharge abandoned vape cells ( FYI pick them up , NOW ! the UK are banning them next year ) ... Use a 5 Volt USB charger , with low Ω current limiter( ? ) .... this is simpler ( 4 components ! ) than the usual little PCBs crammed with ICs , all components available from your junk box 😝..DAVE™🛑

[@jhonsiders6077]

I have several of the industrial ones out of a plant we demolished they have 3 wires coming out of them orange black and white but can’t seem to get them working right bought now sla batteries for them but they will charge if the are unplugged they will come on then plugged back in they stay on Till the battery goes flat then nor charge. . Any ideas

[@bigclivedotcom]

Some maintained lights use a neutral, a continuous feed for the battery charging and a switched feed for direct powering of the lights. But without knowing what you have there it's hard to say.

[@thisnthat3530]

To paraphrase George Bush: "I've got one word for the way transistor Y1 is wired, and that word is 'emitter follower'."

[@Wanton110]

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

[@bigclivedotcom]

Most likely a bad connection causing arcing in the connector, or just circuitry on the edge of going boom.

[@BillyNoMates1974]

wont Y1 transistor get hot when charging a completley dead battery. i.e. highest current draw ?

[@bigclivedotcom]

The incoming current is limited by the capacitive dropper.

[@SrWolf90]

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.

[@RFC3514]

The "Sesamo" part of iSesamo is pronounced "SEsamo", not "seSAmo" (i.e., stress on the first syllable). I mean, you can pronounce it however you want, of course, but it's literally just "sesame" in Italian, and pronounced the same way as the English word, except for the last letter.

[@ralphj4012]

Now only 79p (89% off), hurry whilst stocks last (though factor in an additional £4 for the mains socket adaptor and £100 if your mains socket isn't in the right place).

[@twocvbloke]

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

[@tappel0]

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.

[@tappel0]

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.