I thought it would be worth taking a look at some more recent versions of these. I've had some older ones on test for a while, and they do provide surprisingly useful light on demand in the event of power outages.
For a while I had an issue with a failing appliance heater that would randomly trip the main RCD for the whole house (TT system) and these gave very reassuring light when the place was suddenly plunged into darkness.
The lithium cell in the small unit has now been tested, and is a miserable 150mAh. The lithium cell from the device I showed does fit, but only barely, and with no room for an adhesive pad to stick it in. Other similar vapour devices may have slimmer lithium cells in them that are easier to fit in.
As always, take extreme care when fitting lithium cells, due to their high energy release capabilities. If adding more cells in parallel, make sure their voltages are very close first to minimise current flow as they balance.
The electrical tests at 4.2V (fully charged lithium cell) showed that the small unit uses between 7-70mA depending on the intensity setting, and will stay lit for twenty seconds after the last movement is detected.
The standby quiescent current is a very good 22uA.
I like this style of light a lot. They don't need recharged too often - especially when you boost the capacity a bit, and are perfect little lights for power outages or just late night prowling around the house.
Keywords to find this type of light on eBay are:-
USB rechargeable PIR light
Typical cost should be around ยฃ$โ‚ฌ5 for the small one.
Supporting the channel with a dollar or two on Patreon helps keep it independent of YouTube's quirks, avoids intrusive mid-video adverts, gives early access, bonus footage and regular quiet Patreon live streams.

Two Plasmine Fred Lights USB Rechargeable. They contain Lithium cells and the idea is that you stick them onto the surfaces that you desire to stick them onto using a metal sticker and a magnetic sticker. The magnetic sticker I would guess goes on this and then the metal goes wherever you want it and it means that you can just take it off to recharge it when you desire different size pads because of different lights. Each light comes with this small typical micro USB charging lead and the control is done. What? I'll do with the big one with a button at the end. If you press it once, it blinks twice and that's it. in pattern thread mode, it's also got a dusk Center so it won't actually trigger until it's dark so this problem isn't going to trigger at all now. So if I press again, it does a single flash, then stays lit and if you press and hold it it will dim down and I have to say not really seeing any puzzle modulation Ripple Here that's pretty good. That's very good. Um, and then if you press and hold, you can dim it back up again. Oh uh at this point I should say I'm going to check this if I dim it right down to say for instance zero is it going to be that intense? And password red mode one moment please. Yes, it is undocumented feature. You can also change the intensity by holding the button in passive infrared mode. The measurements of the three versions of these are you've got the 12 LED one which is 11 centimeters long or 4.5 inches. Let me just double check that: 4.5 inches, just a bit over 11 centimeters. You get the 26 LED which is apparently 20 centimeters long and date entries and this is the biggest. It's well, I think it's the biggest Uh which is 300 millimeters long which is roughly 12 inch. Note that uh British measuring tapes have both Imperial and Metric on them. It's just how we roll, we just interchangeably use which comes the closest. So let's take a closer look at one of these. I'll open both of them and we'll see how they compare inside. and they're very easy to open if you take a screwdriver and you just push, this catch in the end slides out revealing the circuit board with its 12 LEDs a little lithium pouch cell in the back. it doesn't look on that big, but loads of room to put bigger cells in. and it's got the USB charge port, the little charging chip, and I'll show you the circuitry in a moment, the passive infrared detector with its lens which they've pulled it through and they've bent the leads over and poked them back through and soldered them. Two reasons for that: it keeps the heat away from the actual sensitive Electronics in the passion thread sensor, and it also means you can use a single-sided board. This one is strangely matte in the back. It's very peculiar. There's a tiny little six pin microcontroller And just the usual stuff. And there's a button in the end. Let's compare it to the other one. So this is basically the circuit board is scaled up. It has the same charge circuitry at this end. The only obvious difference is that this one has more resistor positions and they are in parallel just so they can actually run the LEDs brighter. Uh, just out of Interest Where's my magnifying glass? That is our 10 Ohm resistor. and that one is a 22 Ohm resistor. so it's not running them massively higher power for these larger ones. This one does have a notably bigger cell, but it's also got the positions for other cells either. maybe for one big long cell. or maybe they're just designed to take multiple cells. Either way, there's loads of scope in this one to. well I'll show you what the scope is for one moment, please. So say you were to harvest discarded douche fruits from the side the road. These Vapor producing devices with nice rechargeable lithium cells in them. The construction of this particular one is very good. These contain fat cells. Uh, roughly 500 milliamp hour each. That suggests that one, maybe a 500 milliamp hour cell. but how many could be fit in at one to three four? 5.. you could fit in 2500 milliamp hour worth of uh of douche flute cells into this and it would extend the runtime dramatically. Yeah, how often would you have to recharge it once a year? or something like that probably would be ridiculous. Depends the usage. Um, so let's take a look at the circuitry. I'll just, uh, grab the drawing ax I've got the drawing already because uh, as you may have noticed, they come apart very easy. So I just save some time. we can zoom down this. we can focus on it Boop Focused So it starts off at this end. Very simple circuitry with the USB charge port. it's got one. LED Very basic, the charge program resistor. They've done the absolute minimum in the sense that there's not even the decoupling compassion output. And there is the little Lth07 regular. There's a Lithium cell across the two big bus bars on out the side and at this end we have the uh. the other circuitry I can show you this up closer. to be honest because I've taken a picture of both ends of these. This is what I should have done in the first place. Maybe I should slip these back in before I end up shorting them out one Amendment please. They just go into a little reel. they slide in until the passenger thread detector. Just Hits that and then you take this and it's a silver lines and it just Clips in. It's very straightforward. nice. Construction You can also take the other end off if you want, but it doesn't really serve any purpose. It's just the end with the USB port. I Guess it's just a generic Extrusion Let me grab a little drawing and we'll start with the charging circuitry first. So the charging circuitry has the classic Lth7 the programming resistors deliberately low here: 3.3 K Which means I should say it's high for a low current, so the current is going to be probably about two or three hundred milliamps to charge this. That's part of the limitation of using such a small device when you use these little tiny chips as Chargers uh, they dissipate. They act like a electronic current regulator, so they act like a resistor. and if this is passing, say, 300 milliamps and the cell is at three volts. and this incoming Supply is 5 volts. It's dropping about two volts across this. so that's about 600 milliwatts. that uh, that uh, current 300 milliamps so you can't really go too high with them. but that's fine. Loop Slow charging of the cells is fine. The LED is just like a single. LED lights up red when you plug it in. If it's charged, it goes out. They've missed out the little decoupling capacitor on the output. that's it, really. And then the bus bars with the cell across it. When we get to the other end of the circuit board, I shall turn this round it has and this is a more interesting bit. a little six pin maker controller marked CX Ork maybe just generically designed for this task or just custom programmed standard processor, but we have a 3.3 volt regulator which is a bit of an issue because uh, the passion thread detector here requires a very stable Supply If it doesn't get a stable Supply it can, uh, re-trigger Every time the LEDs turn off and the voltage fluctuates, it can actually cause it to re-trigger and the 3.3 volts is quite high for that. because these LEDs will run right down to about 2.5 volts at low current and the processor may run down to that as well. In which case, once it gets to about the lithium cell gets about 3.3 volts, this regulator won't be able to regulate anymore and you may find it's one of these lights that just keeps triggering. It just won't turn off, it just keeps triggering itself. Um, we have one capacitor on the 3.3 volt side. We've got the WTF cap, which is somehow erroneously connected between the the 4.2 volts from the Lithium cell and the output. You do not connect the output and input of a regulator for the capacitor because that then becomes a coupling capacitor and will couple noise from the unregulated site to the regulated site. I Think they've made a mistake here. That's pretty common though. They could have changed this big track here so it went straight over to the positive and then they could remove this capacitor down a bit and it could have gone from the positive and then it could have had met up the negative connection here, but they didn't or they could remove that capacitor over here. That would have worked as well. Very peculiar. the light sends. The dusk sensor is not built into the passive infrared device. The pattern Thread device is an all-in-one amplifier threshold detector. It does everything. So what actually happens here is that you supply it with 3.3 volts and every time it triggers, it just sends a trigger pulse over to the processor. from this pink pin to the processor. The Dusk Sensor is based on a photodiode and a resistor. and there's the button. There's the transistor that switches the LEDs, There's the resistor that limits the current through the LEDs and there's the base resistor for the transistor, which is a standard Npn, but they've obviously allowed it to use a mosfet as well because they've got the position for another resistor, which would probably a 10 key resistor just to keep it firmly off when it's not getting the signal that is it. I Shall bring in the doodle the schematic and we can explore. It's in its blocky detail because it is very blocky. It is very modular, but very unsurprising in a way. really. USB comes in. There's the 1K resistor on an LED for it's indicating that it's charging. The resistor goes from the negative to the chip to actually set the current. You could change that if you wanted, but I wouldn't recommend it. Here is the Lithium uh cell that we could stack more in parallel with if we desired, the 3.3 volt regulator with its little decoupling capacitor. How generous! I'm going to put one across and that provides the stable supply to the pattern infrared detector which you can't control sensitivity or timing. with that, it's all locked in the microcontroller. We get the button going to the zero volt Rail and we get the resistive divider for the light sensor. I've shown the light sensor it's really a photodiode sort of in Reverse here, but I've shown it as a resistor because it actually acts. It limits the current in a way that it acts like a potential divider. and by measuring the voltage from this pin, it can tell you when it's dusk. you could change that resistor here to fine-tune the value of that if you wish. There's a 1K resistor going to the is it a Y1 transistor I think it was a Y1 transistor y1 which is generic Npn y1 and the 22 Ohm resistor if you wanted. If you wanted super long run time and you had a fairly small error, you could change that if you want. but I don't think the currents that current's that high anyway. I'll probably disconnect the Lithium cell off one of these and then get a current test on it for the ambient Quest and current. and then if I do that which I will do that. I'll put the information down in the description down below, but that's it. Uh, the only thing I'd have changed about this design is this 3.3 volt regulator. They could have used a lower one because I'm sure the processor and the password module will work to a lower voltage and that could have actually made it much more stable. Um, at the end of the when the battery is needing charged and all you'd see then is it would work as normal but it would be a much dimmer because there wasn't as much current flowing through. the LEDs I've shown LEDs all just as one LED here, but they are on Parallel Um, that's about all there is to say and you could stash the Lithium cells in parallel. Just make it last for a very, very long time. Good for a power outages, but that is it. Quite neat lights, Quite smart, not too expensive. They vary between about five to seven pounds shipped in the UK so I'll provide a search link as well that will find these things on eBay but they're actually quite neat lights. The one downside as I say is that they may go unstable when the intensity is low, but then that's your indication that it's time to give them a recharge..

17 thoughts on “Usb rechargeable pir light teardown with schematic”
  1. Avataaar/Circle Created with python_avatars keith king says:

    Just as I'm make a few of these right now. Great timing Clive ๐Ÿ‘๐Ÿ‡ฎ๐Ÿ‡ช๐Ÿ’š๐Ÿ™๐Ÿผ

  2. Avataaar/Circle Created with python_avatars Mizai Slots says:

    i always thought you said microfart untill i searched it up

  3. Avataaar/Circle Created with python_avatars Vaughan Ellis says:

    I have a similar PIR light that runs on 4 AAA batteries (currently powerowl 1000 mAh), that only needs charged 1 or 2 a year, there is no on/off switch, just a sliding battery end cover.

  4. Avataaar/Circle Created with python_avatars big marc says:

    Fek me, I got the big one yesterday!

  5. Avataaar/Circle Created with python_avatars Curtis Hoffmann says:

    Hey, a new way to play strip poker!

  6. Avataaar/Circle Created with python_avatars John DoDo Doe says:

    In my country that changed to metric around 1900, measuring tools still had our national inch unit until around year 2000. Makes sense that Britain would do the same until year 2100, given the late change in daily use.

  7. Avataaar/Circle Created with python_avatars Michel777 says:

    If 200mm is 12inches, i'm way above average

  8. Avataaar/Circle Created with python_avatars Qscreator says:

    i like you show how to work of PIR in this circuit ?

  9. Avataaar/Circle Created with python_avatars First Name Last Name says:

    I have something similar to this except it doesn't stay charged at all. I charge it up and the next time I go to use it it's dead.

  10. Avataaar/Circle Created with python_avatars Dave Fredrock says:

    Thanks Big Clive. I was thinking what a bummer it was that they could go unstable but then also being an indication that a charge was needed is convenient. With greater capacity that might be a benefit in less frequent charges though getting the cells down to 3.v would be cool. I've seen similar lights really plugged recently on Ali.

  11. Avataaar/Circle Created with python_avatars lawson143 says:

    It's an outrage

  12. Avataaar/Circle Created with python_avatars SeanBZA says:

    That WTF capacitor position is for a resistor, as they likely had a cost cut version that removes the 1c regulator and runs the little micro and PIR off the filtered battery voltage. Both will work, just PIR sensitivity will change with battery voltage.

  13. Avataaar/Circle Created with python_avatars Cody-JRT says:

    We use the same measure tape in the USA too. We use both systems in my house interchangeably.

  14. Avataaar/Circle Created with python_avatars toxicpsion says:

    could the WTF cap instead be a link to run batteryless with a power supply ?

  15. Avataaar/Circle Created with python_avatars Robin Cross says:

    For years if not decades in the USA, I remember metric on one edge of tape measures. And of course feet inches and other helpful lengths indicated on the other edge.

  16. Avataaar/Circle Created with python_avatars meet v says:

    One of the cleanest design.

  17. Avataaar/Circle Created with python_avatars Zygfryd Homonto says:

    thanks you you @bigclivedotcom I collected from my friends and family already 100+ of these LiPo batteries. Only 1 of them is not really keeping the charge – all others are 100% OK – thanks again!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.