Dave does a teardown of the Princeton Tec EOS headlamp and mods it with a new Cree XPG LED.
Throw in a quick reverse engineer of the circuit, gratuitous scope shots, torturing a thermistor, a practical demonstration of why you really do need 5 multimeters on your bench, and as usual Dave finds no problems filling up 25 minutes.
Throw in a quick reverse engineer of the circuit, gratuitous scope shots, torturing a thermistor, a practical demonstration of why you really do need 5 multimeters on your bench, and as usual Dave finds no problems filling up 25 minutes.
I bought one of these headlamps after I saw this video 13 years ago. It's still working, but the rubber seal on top of the switch finally disintegrated 😞
I think the LED part wasn't pushed down to where the heat sink worked. I think I fixed it. 1.59 well spent if I do say so…. On to the next thing.
Got one at Goodwill for 1.59. But what I'm going through is the little springs in the battery area are gone. Corrosion from someone leaving the batteries in. Question is do these heat up and cut off. I put springs in it to make the the connection work. Or at least I think it does. I finish watching. Maybe the answer is there.
gosh. I'm way behind time on this video. I have 3 units Princeton Tec Quad headlamp, one of which is dead (given by a friend) – I think what David is saying is correct. Princeton Tec decouples the LED so that they could use the same circuitry of the Quad (4x wide beam LEDs), to fit the wide-angle throw market segment. Smart move!
Please teach us how to build a flashlight driver using AMC7135 or some other current regulation
To achieve the same and constant current over the entire battery charge you could use a Batterizer to keep the LED light up down to 0V of the battery and even below.
Hi, I have 3 lamps and 2 new models are driving me crazy – if you choose say high beam and after a while want to switch off you have to cycle through medium, low, flashing modes where old lamp switches off right away. Can you hack that flaw please 🙂
where can I get this modded please .
When you've just removed the AAA batteries and you're showing us the empty battery compartment, you tell us that the compartment is held in place within the case by two small pins that you ended up drilling out. What are those pins called? I can't quite make out what you're calling them- are you calling them "hit stakes"? "Head stakes"? Something else? If anyone knows the answer, please let me know!
The Cree led is a much cleaner white light as well.
Don't know if you've figured it out yet, but you can add a resistor in series with either of the wires to trim the brightness. There's all kinds of resources on the net to figure out what size resistor is optimal, or you can get a large bag of resistors from RadioShack or the like and tinker away until you find the right one.
My EOS took a dump recently and it doesn't seem like PrincetonTec offers much, if anything, in the realm of support. I couldn't for the life of me figure out how to disassemble my light. Found your video and wanted to say thanks for the great tear-down/circuit schematic. Should make troubleshooting my lamp much easier. I definitely owe you a pint.
No joy…there is no "circuit" to speak of. Just two wires coming directly from the coin cells to the LED through a push switch.
Oooh, you may have inspired me to take apart a GE LED book light I have. The problem I have with it is that it's TOO bright. It lights up the entire room with fresh batteries and defeats the purpose of my using a book light at night so as not to disturb my wife. I'd like to see if I can lower the brightness and maybe get some more battery life out of it.
Great video but we were so close to having analyzed the whole circuit and I regret it did not happen:
what exactly is the function of the IC. Just to divert the power to a specific resistor with each brightness setting?
what exactly does the sense circuitry do?
buck converters give a constant voltage. How exactly does the current regulation take place? thank you
You could use a boost converter to increase the single cell voltage to that required to drive the LED. This uses very similar components to the buck, but a different topology. Wikipedia contains good articles on both. On the down side, the battery current would obviously be greater. I'm not sure how the average AA cell would cope with delivering some 600 mA!
AAA cells are a poor choice of portable lighting since, like I said, one AA cell has almost as much stored energy as three AAA cells. AA cells provide a much flatter discharge curve than AAA cells. Using three AAA cells makes no sense since you can replace them with one AA. You can drive an led form a AA cell with a regulated boost driver. 9V batteries have even worse capacity and discharge characteristics than AAA cells since they use the smaller AAAA cell.
How are you going to get 2.8 V out of a single AA? Plus, as Dave points out in another video, you get the most out of an alkaline battery if you run it down to 0.8V/cell. The more cells in series, the better for getting the most out of them (to a point obviously). A 9V battery probably didn't fit their form factor well.
Another great video, thanks! One question: There is a diode and high-value (100K?) resistor in series between the battery and the IC. I'm guessing that the diode is to provide protection against the battery being installed with reversed polarity, but what is the resistor for?
How can you like 3xAAA? Possibly the worst power format ever. One AA has the same amount of stored energy as three AAA cells. When is the last time you were able to buy 3 cells? You would have to buy at least six cells to utilize what you buy. Single cell always comes out on top.
@dk038967 It's trivial, take the old one out, solder new one in on the same leads.
u talked and talked and talked and i waited and waited on how to actually do the replacement. how and where did u solder one in. can u make a video showing the change?
@myfriendyou1 Sorry, don't have one, no idea.
Hey Bro
I have a Princeton Tec Torrent diving light. I would really like to know how i can replace the led with a cree high power led. Can you advise or point me in the right direction
I have a cheapo Energizer one (like $15 US). It has a more even beam than either your std one or the mod but it isn't as bright as the mod, nor is it water proof. It does the job for me, I only use it around the house, like when I need to work on the AC lines with the relay off.
@EEVblog I mean, all of them are invisible except for commercial interests. If you are a hobbyist, you are doomed to use cheap low quality parts. I am from India.