So my better half is a librarian at the local town library. This library like many others is trying novel approaches to encourage patronage. One idea being put forth is that of a basic electronics class taught by the local retired electrical engineer. So my wife mentioned my flashlight sickness to the EE (without my knowledge or consent) and now I have been asked to lead the final class project in which each attending family will build their own flashlight. In about an hour. On the cheap.
My first idea is a simple p60 build with XM-L and Nanjg ak-47a to be run off CR123 primaries. I can get it done for 12 bucks each including a 502B host and it only involves 4 solder joins and a bit of thermal paste. The only thing I don't like about it is that drug store CR123 primaries may be prohibitively expensive for the participating families and I don't want them buying cheap chinese batteries on line for to make pipe bombs.
So I turn to the enlightened hive for ideas on projects easy enough for ordinary folk, cheap enough for local government grants to fund (less than $20 per completed light), and that can run off alkaline primaries. As I see it the choke point here is the host. What say you?
I can’t see CR123 cells (pricey over time
as long as you can avoid alkalines (leaky), although that topic suggests wrapping 2xAAs in paper to make them fit a 3xCR123 tube, which would be some corrosion protection.
NiMH or Energizer lithium AAs would be safer.
P.S. — applause for doing this tutorial, and congratulations to the library for hosting it
I did a “tweak” with better copper pours and thicker traces (could probably customize silk screen for the class too [if you wanted to go that route ]) {don’t have it shared though}
Since the two AA hosts that popped to mind got used maybe a DIY type Paklite/Safelite. As simple as a 9v battery, a 9V connector, two 5mm LEDs each (in series), and an appropriately sized resistor. A glue gun or other method to pot the whole “light” together completes the basic build. You could get fancy and go multimode with a couple position switch and another resistors. At it’s simplest it’s connect to the battery for one mode on and disconnect for off. It’s way underbudget and in some ways really pushes basic DC circuit learning more than “solder the wires to the mystical board that has everything built in to drive the LED right.” It’s only a couple lumens if you’re driving both little LEDs at max. It’s still not a bad emergency light using a stash of partially used batteries from smoke detectors.
There’s plenty of examples if you do a search. Some don’t use a separate connector instead tearing the case of the battery apart. I’d stay away from those options.
LD 30 is a nice driver. No PWM! Only disadvantage is that with fresh alkaline, the driver goes into DD so low output is as bright as medium.
Joules thief is a good idea for someone doing an electrical course. A simple driver using a single 7135 is also an idea. Can a pot be used to dim a 7135?
Just trying to stay with the point and the EE putting on the show…
I’m going to second the Joule Thief idea. It’s more about “Electronics” and not so much bothering with “Manufacturing”, which is most of what “Modding” is if you use pre-fab drivers. Plus you won’t have to watch the little buckaroos with Very Scary Soldering Irons!!
Getting a Joule Thief tuned up and running is a non-trivial exploration into the arcane interactions between various standard electronics components, and the result is something even some EEs find to be Amazing. (Just mention the words “BiFilar Coil” to a recent EE grad & watch their knees buckle!)
And you don’t even need a battery! Try using a JT with a pickle battery, or just run 100’ of THHN in two opposite directions to ground rods (a-la the pickle battery but with Earth as the pickle) & see how many Volts your dirt produces.
Also, the parts can be scrounged from (e.g.) CFLs, old toys, etc. which encourages recycling.
If you’re really ambitious, you can get an XM-L to light up with one, but it won’t blind you. But an XM-L on a “dead” AA Primary is a joy to behold.
Screwing parts someone else made together and burned-baby lawsuits, not-so-much…
All I ask is, please come back here & let us know what you chose & how it went?
As I’ve mentioned elsewhere, the pictures in the listing you linked to are clearly of a 20mm driver (which Ric also sells over here). The 17mm version will likely either have a similar amount of GND ring to a Nanjg-105c or even less.
I’m not so sure about the “cutting” aspect either. From the views shown in the photos they sure look like regular soldering stars, not cutting stars. If those black arrows drawn into the photo are not covering up traces then they are soldering stars, not cutting.
Definitely not your fault IMO. I’m particularly unhappy about Ric using that picture. In general I support CNQG and respect Ric’s right to run it the way he does… but I suspect that the mix-up with those pics is on purpose.