Inside a solar/mains rechargeable fan / work light. (with schematic)

a technical gift for our amusement from Vince the crew chief and I think he got this in Singapore for 12.9 Singaporean dollars I'm guessing standing camping late with fan from cash converters okay so I have looked online and unfortunately it is available eBay and it's available in pink but that's okay it just makes me feel guilty because Vince probably I had to bust his luggage and brought it back and we've taken quite a bit of space the box itself is quite big and well let's look at the features it's got a fan in it and this is probably good enough try not to blow it at the microphone but it's can op hear it starts off full and then as you turn it down or up it reduces the speed I'm guessing it starts it fill initially just because I that's to give the give a kickstart and get it running this grille is very slightly movable and it's got a flashlight in the side which you can turn on by clicking that way and it's quite bright it's useful looks like a 1 watt beat as the Chinese tenth column and then there's a work light at top you click it all the way and it's got a sort of a wash of light comes out this panel with a matrix of surface mount LEDs how many 1 2 3 4 5 6 7 8 9 10 30 LEDs for charging it's got the option of a solar panel the solar panel does actually look kimball and it looks chunky I would say maybe couple hundred milliamps possibly maybe just 100 milliamps but it's got 1 2 3 4 5 6 7 8 9 10 11 12 sections each giving about half of all which means it's going to be rated for about 6 volts for the rechargeable battery which at this point I'm guessing is nickel add not nickel metal hydride I could be nickel metal hydride given this a pedigree of this but I'm hoping it's lithium does it's a lithium Reserve anything on this I didn't see anything in the box so it's got a handle that folds up and it's got a charging port now notice that the red LED is lit at the moment that's just pure the light hitting solar panel is quite sensitive the figure-eight leader comes with is that one that starts to give clues as to its pedigree here it's a very small figure eight lead that goes into what looks like a standard figure Eight's of socket and if I plug it in with my recently bought Poundland adapter if I plug it in the red LED lights very brightly and it takes a charge not sure much charging current is I've not got this stuff to actually test that with not here anyway it does allude to the technology because it says where does it say it and please connect to 20 volts socket charge till the battery the charge of your heart please do not use from charging in order to avoid electric shock and this makes me think of the death Daleks the capacitive dropper charger flashlights that are available that also the sub token gesture solar panel more this one seems like a proper unit but what this lacks is the USB output which is good because it is USB overlay another ones that made them possessive hazard so let's take it to bits that's what we do so I can see a couple of screw positions here I can see a couple of screws here and a couple of screws underneath along with some of feet okay let's I've just ticked all the screws out that seems like a good idea I'm not sure if it's gonna wanna use things that does this on the screw yes it does yeah you can see the circuit board I can see the battery that looks like one of those suit lead-acid batteries in there let's say it get a bit closer to that you see that in there okay let's continue taking the screws out this is quite nice this assemble it's quite common of these lights that you've got the one white LED wanna now even your heat sink that then screws onto the back of reflector it's quite a nice idea I'm not sure along the run the unit runs they claim quite a long run tape and a fuel charge and certainly the phone we've had it running one evening with a fan because it was a rather hot day and it did pretty well a couple more screws to take out here gonna have to be careful not to short anything out this is a student accommodation 11 at the moment for a for work while the students are we in the holiday and there it's good sense of smoke detectors which is not good Oh does this thing have to cough oh right think that's how it comes apart any more screws I don't know but yes there is I didn't take one of the screws out that will be why it's not coming apart right here it is a capacitive dropper it's got quite a big batch in there all the DS air unplug that's quite nice so can unplug that and forget we ever get the fan motor coming down it everything plugs in that's nice and discuss transistor for the motor so it's viewing probably the current drive to a doubt it but pulse width modulator yet it will just be varying the air bias to the base or gate to painter what it is right so let's take a closer look at this actually you know what I should reverse engineer at first but let's take a look into here so what I'm seeing here is the classic big capacitor here I'm seeing to redirect for us what's that about and there's a big batch in the back the multi ways switch which I has a couple of resistors I'm guessing since this is doing the LEDs that one resistor will be for the led torch the flashlight and one maybe for the other panel that can look there's the two connectors right next to it right one moment please I'm going to whip this circuit board out and we shall reverse-engineer it I will not lie that took me quite a time to reverse-engineer because there's a bridge rectifier composed of four diodes here and then there's four other diodes each with a separate function increasing it was actually quite complex so let's full that hurt and I've split it into two sections because it makes more sense that way so the first is the battery charger and it charges the battery at 100 milliamps approximately so we've got the incoming supply the AC supply which is designed for 220 volts but one works at 240 and would work 120 volts it comes in via this capacitor and the capacitor allows a portion of current through in each half wave there's a discharge resistor across that to stop people from getting a bit of a zing if they pulled this plug out and then touch the pins it just makes sure that gets discharged if anything I would like to have seen that little bit higher value like 470 K so that then comes the bridge rectifier and I'll come down to the sir LED in a moment this is the charging LED so good should be direct fire full bridge rectifier gets smooth by this electrolytic capacitor 220 make fire 35 volts and then charges this why I guess is a sealed lead-acid battery here but there's a diode from the the battery's negative connection down to the negative from the bridge rectifier to pasta and that's - that's for a very specific reason the voltage because it's charging that battery is capped to about 4 volts plus the drop across the bridge rectifier me about couple of volts so the voltage here is approximately it's halfway but it's it that it's going to light this LED but it will be limited to about 6 volts so that LED glows dimly when it's charging and has a visible flicker because it is a little late in each half wave the battery can also be charged from this solar panel and it does so via this diode here that's one of the extra two heads of this and the another diode is used from the solar panel going right across it's used to block current flow from that side but also tell though the solar panels are actually like the LED - and the let me think here let me think the other diode in the circuit is used for the fun disable I didn't realize that had this function when you've got it in charge because the fan draws quite a lot current it turns the fan off and that sums up the charging circuit so I'll just pause moment trial if you want to freeze frame and explore the habit of circuitry and then we'll go on to the next bit of circuitry which is now I want before turn over keep in mind that when the fan unit is charging fan disable gets pulled effectively negative respect is your the zero grill the LED is in the fan I shall just nudge that up to lifting Fitz and that's about it there let's start with LEDs because they're easiest it goes from the positive 4 volt real via the switch and the switch S three positions middle is off either side is via a 4.7 ohm resistor though the four point there are two 4.7 ohm resistors the current is slightly different you've got this spot LED which is a typical one more chip and it's running at 170 milliamps the other one goes to the parallel array of 30 their surface mount LEDs and it pass it goes through a simple resistor and it passes 215 milliamps because they're these LEDs are being run quite low so their forward voltage will be a tiny bit lower whereas this one's being run about effectively half a watt so its voltage will be slightly higher so that explains the difference in the current the fan the circuit is the most complicated FET here we've got the rotary switch with the potentiometer here and when you turn it on it makes circuit to the power of the fan which is then shoulde by this transistor down here which is operated in what they call its linear region they're basically viewing the base current to this transistor which then regulates the current flowing through the fan it means that this is acting that a resistor so it will disappear a bit of heat the potentiometer also has this variable resistor section as well as that switch and that forms a potential divider with this one k5 resistor and then there's another two resistors one coming from the tap there and one coming from the wiper arm through this 1.2 key resistor and I'm reckoning that they've balanced the values here so that if you were to put this wiper array up to the 4 volt rail it would not limit the current so this 1.2 ki resistor is to limit the current to the maximum current into the base and that will also set the maximum speed that's probably the the transistor tonfa on this 330 ohm resistor I think is to nudge the value of current flowing into the transistor to a sort of give it an absolute minimum value so when you turn it down to the lowest setting it won't just turn off completely it will always keep running at that speed just to make sure that the fan keeps turning and that's fundamentally that's the potentiometer and three other resistors to set that sort of variable range the fan disabled here is the one that is in the previous page at piltan just below negative basically speaking it turns this transistor off completely by shunting the gate current and I can prove that let's ahead let's zoom out here let's bring a circuit board in let's plug the means into it it's not plugged in yet I shall move this so that we team up I'm just gonna zoom back in this because what I didn't do there was let you guys take a brief snapshot of this if you want to freeze frame and take a look at the circuitry so now zoom back oh again and I'll show you that function where it turns the fan off I can find so plug this into here I won't plug it in yet let's plug the battery Enrique now sure I get into the rate connection and we'll plug the fan technically speaker probably plug the LEDs insuring it visually but let's to the phone let's make lots of fan noise in the microphone so no if I bring this and if I plug this in but don't turn it on at the wall so it's not charging and I've turned this round and I've turned the fan down to lowest speed where it's probably not making make fully hissing whooshing ear noises alerts rat thing about if I don't charge this by turning on it turns a fan off and it doesn't match the setting I'm holding my hand up here just to block the mic front of it from the ear floor if I turn there that off again it won't actually start because there the fan was at its lowest setting so it needs that little bit of a nudge to start they see I can block make phone here to avoid hissing noises so even if I turn it up to its full speed setting and then click that switch while it's charging it kills a plan completely I should turn off there so that's the circuitry it's surprisingly complex the bit that took the most to work out was those four diodes and the circuitry used for regulating the fan motor speed just by operating a transistor in its set of linear region and it is a standard NPN transistor a forgotten number that transistor hold on second just give me a second I'll just faint number of that transistor it was 8 8 2 P was that a DAT yes it was a d8 8 2p transistor which is a generic NPN transistor so there we go it's interesting it's actually ok it's a very simplistic circuit but it does charge that consistent 100 milli for that even though it's just using a capacitor simple capacitor here there's no over VOC protection I guess it's just relying and maybe charging a hundred milliamps all the time there's no cap to what it charges this but maybe the sealed lead-acid just simmers away gently when it's left trickle charging for too long other things were they've naught is this housing initially I thought this was all bonded together but err this batch actually slips out of here so this air carrier doesn't just screw the battery down but also as a mounting post for the circuit board for the two men to push the circuit board and you'd have to be careful if you took this apart not to put there too long as screw in New York that could actually penetrate into the battery because it's smaller screws but there we go it's an interesting little unit so I'd like to thank uh Vince the crew chief for supplying that for our entertainment it really was quite interesting

Channel: bigclivedotcom

Views: 77,128

Rating: 4.9549179 out of 5

Keywords: rechargeable, solar, work, light, spot, wash, flood, capacitive, dropper, charger

Id: 4mvMScvexjc

Length: 16min 9sec (969 seconds)

Published: Thu Aug 15 2019