The little mad scientist in me

Just for fun on this wonderful Monday morning I thought I'd post this rather fun photo of a little bit of LED experimenting I did last night. As a bit of explanation, this is a picture of a little experimentation I was doing last night. The two disks on the left are triple LED puck lights. I built this setup, using an electronics breadboard as the intermediary, to test a couple triple LED pucks to see how much power they were drawing. The results were rather surprising. Depending on the battery used, their draw changed. That's probably not surprising to you guys, but it was to me. Anyhow, if IO used 3 AAA's to power them, the total draw for both likes in parallel was about 100ma. For 3 AA's, it rose to 125ma. But if you connected 3 D's to it, the amount jumped to 150ma. Kind of intriguing if you ask me. PS, no LED's were harmed in the making of this experiment, although I did where safety glasses just in case something did. lol. EDIT: Odd, posts don't seem to keep their formating. o_0;;

I got you beat! :tinfoil:

Yesterday evening powered up a Nichia 21W power LED (a Chip-on-Board module, to be exact). Cut up a P3 CPU cooler to serve as heatsink. CoB module -> heatsink contact was good enough to give me trouble soldering wires to the thing!

Used magnets to stick 10x 18650 cells together as a ~36V DC source, and a board with various power resistors to control LED current. Had it up to 10W+ for over an hour, and slightly above rated power for a few seconds several times. Which in this case translates to 1000-2000 lumens range light output, FYI. Found out that heatsink handled ~7W continous, more possible but then things got hotter than I liked.

Finally I used hot glue to stick on a small reflector taken from an old/broken plastic flashlight, and thus give the light some direction.

Will be aiming its power supply (to do!) around the 10-12W mark, with dimming function. To be used for turning a 20W halogen desk lamp into a power LED light. The electronics part is the easy part for me - but finding the right parts can be a journey sometimes.

Unfortunately I have much less time than I'd want for this kind of thing, and no decent work area either. Still have a 40W CoB module awaiting similar treatment (I intend to power that thing near its rated power in regular use).

lordraiden said:

Anyhow, if IO used 3 AAA's to power them, the total draw for both likes in parallel was about 100ma. For 3 AA's, it rose to 125ma. But if you connected 3 D's to it, the amount jumped to 150ma. Kind of intriguing if you ask me.

Click to expand...

Bigger cells = lower internal resistance = lower overall series resistance in the circuit. In simple LED circuits that tends to increase current.

HAHA! I love it, RetroTechie! Also, the revelation about bigger cell = less internal resistance does make a ton of sense, tbh. Also, while I didn't picture this above, I've come up with a simple system, using PVC parts, to create a battery bridge for projects where my power need is less than the number of batteries held by the battery holder. IE, all I have is 4 cell holders which would create 6v of current, but I only need 4.5v. In cases like that, just plug this spacer in, and bingo, you have your 4.5v and the battery holder is satisfied that it has all 4 slots filled. I'm also working on a design that allows me to insert a switch as the battery spacer too for certain projects.

Most electronic hobbyists use a regulated power supply rather than heaps of batteries. In fact I would have too, only mine does 24V maximum, and this LED needed ~30V. Stacking those 18650's seemed quicker/easier than wiring multiple psu's in series.

Many beginning electronic hobbyists start by building such a power supply (LM317 is popular for this purpose). Right after figuring out how to use a soldering iron, and how to cut holes in aluminium plate (to build equipment like power supplies).

With that in hand, experimentation with a LED = power supply + resistor(s) + turn knob(s) + measure.

Btw pro tip: your multimeter could use an upgrade! A $10 or so upgrade, that is.

Thanks. I've got a digital one, but I prefer this one for the "quick and dirty" work like this where I don't need all the fancy to the decimal point values on stuff. I only haul that one out when I need more precise measurements.

Hmm, it would appear I may have found something that'll give my little creative mind a bit of a boost. Was up on Amazon and found two items that I believe will allow me to be a bit more flexible with my voltages and battery configurations while experimenting. Since I'm not allowed to directly link them here, I'll give you the names to search for. Both seem like interesting concepts worthy of a look. The first is a "PKG(4) D-Cell Modular Battery Holders". This gives "Plug and Play battery holders" a whole new meaning. The second is "Battery Holder Set With 4 Different Outlet Supply Voltages". This is an odd contraption that takes four single battery holders and allows you, through the choice of four different locking lugs, to decide what voltage you'd like to operate at. It's rather intriguing, tbh. Anyways, thought I'd share those since I found them while searching for items related to this experiment. Oh, btw, I've made another breakthrough on this. I won't show you what I've done yet as I'm not done, but when I am this will be very cool.

Okay, I haven't had much time to work on this, but I've come to some interesting discoveries. First, the 3 led lights don't produce enough to keep me happy. 5 led puck lights, much better. Second, unrestricted they draw WAY too much power. But a nice 10olm resistor seems to reign that in nicely. I got from 225ma unrestricted to a comfortable 100ma at 2v, which kinda surprised me given that I'm feeding them 4.5v, so I figure that has something to do with the natural resistance of the LED's. As far as the voltage, that didn't change between resister and open circuit. At least not enough to detect. So basically my rig is either a single or double 5led puck (depending on the size of the room I want to light), a single 10olm resistor, a three cell D-battery pack providing 4.5v and a home light switch like you'd use for track lighting. Why the switch you ask? lol. Wall mounting light flicking convenience. Just mount on the wall and use just like a regular room light. I'm designing this whole thing more for easily mountable and removable emergency convenience lighting when the power goes out, which it has a habit of doing quite often around here. Lights go out, click, click, click, and you have ready to go battery powered room lighting that gives you a degree of normalcy while mains power is out. The reason for the D cells is actually pretty simple. It comes from Peukert's law. The more juice you draw vs overall capacity, the faster your battery dies. As such I've found a D provides longer life per amp hour of capacity draining at 100ma than a C, which provides more than a AA, and so on. I'm not talking overall capacity, but rather available at a particular draw rate vs its manufacturer rating. Of course, I'm preaching to the choir with this as you all likely understand this pretty well, but I figured to explain myself at least a little. Also, I found a neat way to get your LED pucks to spread their light out more efficiently across the room instead of projecting a concentrated beam at a single location. Just put a couple layers of Elmer's Glue-All, aka "White Glue", over the lens and it then defuses the light out really nicely for very little intensity loss. Anyhow, I thought I'd update everyone on how it's going. Yeah, it's a hillbilly hack, and it probably will look ugly in the end, but my thought is this. Do you want it to look really nice and be clunky, or do you want normalcy inducing easy to use lighting? I'm shooting for option 2. If I can do both at some point, great. But for now I'm good with just "it works". PS, I'm just stumped why this forum software won't parse my line feeds in my posts and just lumps my text in big blocks. o_0