Solar Light Circuit Explanation! Clever little design... 

Thanks a million Kevin! I've been hacking at my wife's solar lights that die for YEARS trying to get them going again - she loves cool glass, and the electronics that come with the cool glass are always crap so it's been a huge pain to recover from corrosion, re-solder broken connections, or even just tin the garbage wire that they use. The 4-pin Mystery Silicon has always been present; one switch, what I thought was a resistor, solar panel input, and battery contacts. Today after a particularly cool looking one died, I finally decided I'm going to dig deeper and figure these things out - I'm going to design & 3D print housings and come up with my own battery+solar driver circuit dammit! A little Google effort and I found this video - SUPER HELPFUL! 4-pin guy is an ASIC! Scooby Doo Mystery Solved! Thanks again! :)

nice job Kevin, you have a real teaching type of presentation. You present in depth information while not showing off and seem actually concerned that your listeners are getting the information. Kudos

I was a HVAC service tech for years and I've always been interested in circuitry. I was always tearing apart circuit boards to see if I cold repair them or see what the issue was. I found this interesting. Thanks for the info🤯👍

The approach of using the oscilloscope to show the DC-DC conversion was simple and elegant, great job!!! it shows the reader that it is not a simple DC circuit, but a complex and robust IC . Thank you!

Looking for a fix I ran into this video from a very smart man and I was mesmerized even though I could not understand all the technical jargon Kevin was saying, it was intoxicating and made me realize why I am such an average uninteresting dude that can in most situations never complete a task with out running into complications of my own creation...Of course I soon as I saw how technical this was I should have immediately gone to another page but no I was glued to the lights and the graphs and the schematics and all the fancy technical names for these little electrical thingiiees that made me want to be smart like Darrah so that I could fix the darn solars! Not to be in this lifetime. Ok done, time for a coffee and some medicine...

great video, love the way you explain everything.

Your tutorials are awesome and I want to thank you for that. I learned pretty much through your Tutorials. Keep on staying creative and sharing your knowledge. Wishing you a merry X-mas and all the best for your future!

Light(光)Control (空)Switch(开关) (top-left), Over (过)discharge (载)protecion (保护)(bottom-left), Switch(switch)-type(型) drive (驱动)circuit(电路) (right)

great video, much more in depth than I was expecting.

Had to watch this, I picked up one of those tops, a bit different, mine has the 8 pin package but pretty much the same, found it on a table at a community yard sale for a nickle. It was so dirty I had no idea what the hell it was till I got it back to the camper and cleaned it up. Put an AA cell in it and it came to life. Sure not sure what I am going to do with it, but I think to start with the solar is coming off and will be re-purposed to run some other device of some sort. They are very interesting, I built my own joule thief following Big Clive's video and it works great running a high output LED from a dead (mostly ) AA battery.

Awesome analysis!

Great video Kevin. More like this 😀

Now if i could get my hands on that chip 🤔, greate work, You have tauht me more than any teacher has ever done, keep it up

Hi Kevin, I have been looking every night at my sad outdoor LED lights. When they do light, they look great with the snow around them. But like you, I have been pondering an upgrade. So I would love to see a follow up video, or two, with some recommended upgrades.

I would love to see a video on DC-DC boost converters! good video, too.

wow im straight off to my local pound shop to get some , great stuff

Nice Video explaining the board. Question, is it inductor problem if LED light stays on while solar panel exposed to light?

Great job. Thanks.

I was hoping you will show how to "upgrade" this circuit..

Wow a connector i did not expect that They make them cheap as posible but still spend some cents on a connector

if you replaced the 600mah battery with a 900mah or higher would it stay on longer? or would it just need more sunlight charge time, or would it screw up the ASIC?

thanks kevin you rock

That was interesting. Eliminates the need for an LDR or other such light sensing circuit. Basically, your cell now doubles as your sensor.

Is there any way to "do this" such as to prevent battery discharge past _1.8v_ and operate at around 2.5v ? I ask not for just putting two nimh in series, but to utilize the awesome 2.2v _lithium titanate_ battery which withstands charging in -20 C and high temps, too. Also (supposedly) some 7,000 - 30,000 charge cycles! I imagine having to use more parts, since I couldn't afford to have a dedicated chip made just for that! And, thanks for this video! I am "testing" a 1500 mAh one by charging it in the sun (a couple of days were just 15 F) and discharging LEDs ALL the time, about 45 mA (3 Amber LEDs in parallel) each with about a 13 ohm resistor. And with NO diode, because that would drop too much voltage from the 2.5v ~200mA panel. It doesn't seem to lose juice through the panel at night. will last for about 48 hours or so without a full charge (only gets up to about 2.6v because too many tree shadows and LEDs on all the time. Of course, there's less current the next day, so, seems to last a lot longer (and has yet to dim completely). The "switch" is just me taking the battery out of the 18650 holder... So yeah, I want to be able to do it right with a chip like the QX5252 that would work for this 1 volt higher requirement. I've searched and came to the conclusion that the LTO battery is very unpopular (due to its low voltage? Can't even find a cheap protective circuit board like they have for li-ion). If you have the expertise to design such a board, I'd be able to pay after I get catch up with bills (painter in the winter, I am) ! Thanks for considering!

If I want to use a 1.5 A and 3.7V lighting, which transistor do you recommend?

What is the highest safe voltage input from the solar panel... want to use the guts of a solar light and replace the solar panel with a 5v inductive charge coil receiver for a string of led lights. Does this have some kind of over voltage protection/reduction on the input side from the solar pane feed? Not in any way familiar with this kind of thing so not even sure how to ask question.

My biggest problem is solar panel itself, seems that either photo resistor drops dead or they are already selling these lamps with screwed up panels, as in 70% of bought, they dont react to day-night, so 1st day they lit up, drain battery and NEVER recharge again, can this thing be fixed ?

Chinese says: Light Control Switch (top-left), Over discharge protecion (bottom-left), Switch-type drive circuit (right)

Thanks Kevin. Been waiting for someone to do a video on this.! I need longer run time, shorter charge times. Battery capacity seems easy to increase with higher capacity NiCds available. And could I use a LSD NiMH or won't they charge well at 1.2V?

How you fix that switch so that it doesn't short out the lights. Mine won't come on now but if I move the switch back to off then back to on they flicker but don't stay on.

Hey Kevin, do you have qualifications in electrical/electron engineering by any chance? great vid as usaul

Thanks a lot for that

I was also waiting to see the RGB LED and WiFi interface. What about that battery to make it last longer through the night?

I still don't understand where the measurement of the available light is done to turn the LED On or Off. There must be some critical voltage in the QX5252F that's uses the solar panel as a LDR like device.

Two Questions Kevin, How many SMD LEDs do you think it could run? Do you know how many mH is the coil?

That ASIC will probably have a comparator?

Hey Kevin, thanks for the great explanations. I've been looking into light/dark sensors a bit and I'm just curious if you know a solution with a low quiescent current drain. A 'standard' Darlington pair sensor with a photoresistor and two transistors works well but has a drain of a few milliamps. Would a setup with op amps work better? Thanks.

Impressive! Can you take a electric pump and make it solar? Is it possible?

wow those are fancy, jst connector, led driver ..

Any one knows eable library for TO-94 package so that I can put QX5252 on the schematic?

I took apart a Halloween lantern thingy, and found the identical circuit as this. How do you determine what looks like a resistor, is indeed an inductor?

I have a small garden solar light that isn’t working but the identical one is working really well. I have taken apart except removing the cell itself (which can be if needed) and found my red positive wire is no longer connected to the cell. Can someone tell me where that darn tiny red wire attaches? This light has blue, red and black wires, 2 of each. I can send a pic and would most likely be really simple for someone who knows the basics.

It works like a joule thief.

Help--something wrong with the solar panel or light sensor. Light goes on but won't go off when light is present. What could I do to fix it? There are like 6 of them but only 2 currently working. They are really nice copper or copper-look design. I love them and can't afford to replace them. Any suggestions to fix them? They don't have the plug thing--everything is soldered. Any help would be appreciated. Thanks.

did you made its Schematic? i want to know the position of switch.

Does the solar panel double-up as an LDR replacement you think?

Mine has a chip labeled Aj7y1. Only 5 pins. Smd chip. Anybody know what this is?

I was also hoping to show how to upgrade

i got some of those but they filled with water the first time it rained and broke

/Would it work with a 500uh inductor

Dang , that one looks like its constructed WAY better then the Dollar Story variety I mess with. They even used a Connector ? LOL All that and then they install a Wimpy azz 600mAh Chiniesium NiCad. Just replace that with a real Sub C NiCad out of a old Drill Battery Pack and you would have something. The circuit is working employing the Joule thief concept. en.wikipedia.org/wiki/Joule_thief

Nice video. When you cover photocell the light goes on not when you cover solar panel

Chinese writing on spec sheet says: American f-35 fighter has carbon fiber wing spar.

Source unit = power supply, when did this happen?

Basically a joule their circuit

i have this type product. the same

Your 600mah don't last all night? My 200mah ones do. O.o

im late to the party, but its basically a Joule thief with a solar voltage switch.

Sort of a juele thief circuit in disguise.

interesting

Please, why didn´t u draw tha whole circuit, an then draw a circle (on your drawing) around the components that are inside this intergrated 4-pin-circuit...??? This´d have been much more comprehensive and educational... I very well understand the clever idea behind its function, but knowning nothing about electronics, I cannot apply that knowledge, for that I´d need the circuit, cause I´m an absolute beginner!!! still thumbs up...

You started off with... "I want to see if I can swap to a lithium battery" and "a led upgrade." After 12min of electrical circuitry gibberish... absolutely no conclusion or answer to your own original question and provided us with zero information to either of the upgrades you proposed. No answers; No parts list; No build demo... Nothing... you sir are an engineer.