PackRatWorkshop BOBBLE GENERATOR Page
This is what I call a bobble
generator. It is designed primarily for charging
It's a very simple idea where
you have a coil of wire with a loose magnet inside the coil. You pass
another magnet near the coil and it causes the magnet in the coil to flip
around at high speed generating at least one pulse of power from the
coil and sometimes more. There is very little noticable drag
from flipping the magnets in the coils. On a bike you don't even
notice what little drag there is. I have two of his coils using
4 wheel magnets on my recumbent tadpole trike's rear
wheel. The two coils operate two home-made rear taillights that have
9 leds in each light. They work very well and are really hard to ignore
because they flash pretty wildly the way I have them wired.
The 2 pictures below give you an idea of whats happening when the magnet goes by the coil setup. There is another really good diagram at the bike light website above. He also has a small movie you can watch that show one of his setups in action on a bike and you can see the magnet in the coil spinning around a few times every time the magnet passes it.
I don't normally advertise for peoples products and ideas but this is the best bike lighting system I have ever found. It is extremely reliable and works great in any weather. You really don't feel any drag at all from the system when you are riding, it just works! It improves on the old fashion wheel rub generators in every way and the leds don't burn out like bulbs always do (normally at the worst possible time!)
My original prototype had 200 ft of 30 gage wire per coil and the voltage output was 3 vdc with average 20 millamp pulses from each coil at about 100 rpm.
This was the first version that was spinable. My first tries were just to see what a single coil and magnet would put out and if I could use more than one hooked up in series or parallel. This one only used 4 coil setups on each side and 3 magnets on the rotor. It would light up 5 leds easily and actually keep them going for a few seconds after you stopped spinning the rotor due to the charge built up in the capacitor on each coil. I decided to go ahead and try building bigger versions after this as it worked well.
This third version works
a bit better than the last two. It is made with 24 coils, 12
per side and uses 6 magnets in the rotor. (magnets from a different
supplier!) I went with 1200 turns of 30 gage on a 1 inch by
7/8 inch section of pvc pipe for each coil. Each coil contains
a 3/4 inch by 5/8 inch disk super magnet. The coil boards are
set up so each rotor magnet passes a coil on both boards alternately in a
left-right fashion. All coils are connected in parallel to a
common set of output terminals. So far 60-70 rpm seems to give
the best output.
I used 8 coils and 8 magnets
on the rotor. The rotor magnets are 3/8"
squares. All the coils are wired with individual full wave
rectifiers like the other versions and this time they have 150uF/50 volt
caps. (I had a bag full of these in my junk box) All the coils
are wired parallel to a common output.
This generator setup was installed into a small savonious rotor windmill to test it.
It has no problems supplying power to operate a small am/fm radio with just a light (7-10 mph) wind and it's been used to charge a 7.2v battery pack also.