A mini electromagnetic lantern that can be recharged by shaking
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Tested using the new voltage doubler circuit with my latest coil
I will still need to test with supercap hooked up to see charge time, but I figure this might help to charge the supercap closer to it's full voltage.
Ordered some 10uF ceramic caps to test.
The order of 32 awg magnet wire came in so I wrapped a new coil, this time I also designed and added some edges to make the wrap a bit easier, this makes it more like wrapping a spool and has small holes for wire to pass through which helps to organize the wire.
I did a 22 mm section in the middle with 10 layers which equals ~800 turns.
When testing with the same generic magnet setup as before (10x 1.5mm thick x 12mm magnets) I was now able to generate ~1.5v..
Testing with 2x 10mm thick x 12m N52 rated magnets that I ordered https://jc-magnetics.com/Magnet-Cylinders/Magnet-N52-12mm-12mm-Discs, I was able to get this up to 2.5v, not exactly as much as I really wanted, but should be enough to get it working..
Started prototyping the joule thief circuit to see if I needed to tweak the components a little.
I wound the toroid with x2 24" 28 awg lengths of magnet wire which ended up with ~23 Turns.
I then set up a basic run of the mill joule thief circuit.
Through testing I found that a 20k potentiometer worked better for providing a good dimmer control vs 5k. I placed the pot between one of the outputs of the toroid and the transistor base.
Manually charging the supercap with a battery to 3v allowed me to test the run time and voltage.
I was able to run a full 1m length of 5v cob led string for ~2-3 min from 3v all the way down to ~ .4v.
Built a coil to test the power generation using some 28 awg magnet wire.
After marking out ~25mm section in the middle of the 1/2" tubing I did 6 layers of 28 awg, gluing it every so often to ensure it didn't uncoil on me.
This came out to ~250-300 turns.
When testing with the magnets I was only able to generate ~.5 volts. I tried with both 5 magnets and 10 and it still roughly the same voltage output. I think I need to get more turns to get to a higher voltage.
The issue is with the 28 awg wire I am only able to go 1 or 2 more layers before I use up all of the space available for the outside 1" tubing. So I need to try switching out to a smaller gauge.
I went ahead and put in an order for some 32 awg which should give me close to 2x the turns in the same cross section.
I will also redesign the drill holder and a couple coil edges to help make the process a little easier next time. A tighter and neater coil should generate a higher voltage.
Updated and Refined the design to better fit the components.
- Added a threaded top cap to allow for access to electronic components
- Added a 2 piece base to allow a 9mm switched potentiometer to be used to turn the light on/off and dim.
- Cleaned up the general design to make it look better.
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