Im looking for ideas on how to make a circuit that will charge using inductance, very much like a cordless toothbrush. Hopefully I wont have to tear apart a cordless tooth brush for parts.
All the circuit has to drive is around 4 or 6 ultrabrite flashing LEDS (hopefully, all flashing at a different rate) for as long as possible (hopefully for around 30 minutes...thats it). As well, can I use a Supercap to power this circuit instead of rechargeables?
My other option is to use the power generator from a "shake to charge" supercap flashlight. Could such a circuit run off of this type of generator, and how long will the charge last between shakes (approx)?
Any suggestions??....thanks guys.
Kim
Wireless (inductance) recharging
Wireless (inductance) recharging
Kim..The man with the cute little girls name...and Frankensteins face and body.
Hi there,
The basic idea is to use two open frame inductors where the
magnetic field of the first one can reach the core of the second one.
The first one is then driven with a square wave and the field
transfers the energy to the second one, which can be maybe 0.1
inches away from the first one.
There are a number of ways to do this. You can wind two E cores
and have them face each other while you drive one of them with
the square wave. You can also use a split toroid core where you
wind turns around each half and have the cores face each other
as one is driven. You can also use two pot-core cores in the same
manner. The main idea is to split the core and have the two
halves facing each other.
It's not as good to use two straight bar cores because lots of the
energy will be lost because only two of the four faces can actually
get close to each other. Closeness is part of the trick...the closer
you can get the two halves the better...because the field decreases
very quickly with distance.
Graphically, the idea looks something like this:
[] <-- core before being split
[|] <--core after split with a thin separator material between faces
Note for each 'face' there are two places where the cores meet,
not just one. Each face has a N and S pole.
The basic idea is to use two open frame inductors where the
magnetic field of the first one can reach the core of the second one.
The first one is then driven with a square wave and the field
transfers the energy to the second one, which can be maybe 0.1
inches away from the first one.
There are a number of ways to do this. You can wind two E cores
and have them face each other while you drive one of them with
the square wave. You can also use a split toroid core where you
wind turns around each half and have the cores face each other
as one is driven. You can also use two pot-core cores in the same
manner. The main idea is to split the core and have the two
halves facing each other.
It's not as good to use two straight bar cores because lots of the
energy will be lost because only two of the four faces can actually
get close to each other. Closeness is part of the trick...the closer
you can get the two halves the better...because the field decreases
very quickly with distance.
Graphically, the idea looks something like this:
[] <-- core before being split
[|] <--core after split with a thin separator material between faces
Note for each 'face' there are two places where the cores meet,
not just one. Each face has a N and S pole.
LEDs vs Bulbs, LEDs are winning.
the wireless toothbrushes use a coil in a coil approach. The base unit is wound around a tube that the toothbrush handle can be inserted into. The handle has a coil, battery and controller electronics in it. That seems to be the easiest way to go. Maybe not the most efficient but very convenient to use.
If you have an old appliance around you might as well canabalize the charging coil since it's already designed and built for you. Or you could take it apart and copy the design.
One point worth noticing is that the charger has a series capacitor so that it is a resonant circuit tuned for when the applliance is charging. When the coils are seperated the circuit is mistuned so it draws(wastes) less current.
One point worth noticing is that the charger has a series capacitor so that it is a resonant circuit tuned for when the applliance is charging. When the coils are seperated the circuit is mistuned so it draws(wastes) less current.
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