Help with shake generator light up wand

[brit]

Hey this is my first post here. I'm thrilled that my 8 year old wants to build a circuit. the goal is having a harry potter wand that lights up only when you move it, and the LED light would stay on for 2-3 seconds after the motion. so kind of like a shake flashlight that drains immediately.

my current plan is to use a magnet coil generator in the handle, which powers an LED at the tip. However to get the response we need, I'm trying to put a capacitor in parallel (along with a resistor) to try and drain the charge slowly, but I'm still stuck. here is what i'm thinking:

right now our coil only generates about 0.5V on each "shake", and the LED is 1.7V.

How can I prevent the led from immediately draining?

Can I make it so that the capacitor doesn't drain until we hit 1.7V (so maybe 2 shakes are required to activate) any ideas? thank you kindly!

 

[Externet]

Welcome.
A single shake to lit a LED for a couple of seconds would need a considerable generation of energy from highly powerful magnet and a properly matched efficient generating coil.
Better re-direct your efforts to a mercury switch/manual pushbutton to lit the LED from a battery in it.
Seen clear bouncy balls at the 99 cent store that light up its internal LED when shaken/dropped. They have a sensitive spring that initiates an 'on' timer. Explore re-purposing/adapting one. Cheap enough to try and retry many times. Coin built-in battery included ---->

Or, modify longer, larger,...---->

 

[brit]

thanks so much for sharing, I'd love to try and make this work for the sake of the magic of no batteries. Can you clarify "highly powerful" and "efficient coil"? so far I bought rare earth magnets which are quite strong, but with my coil (i'm using a thread spool of 0.2mm magnet wire) i'm only getting 0.6V so far. How could I boost this aside from winding it thicker?

- does shrinking the air gap between the magnet and the coil matter more?
- or should I simply keep winding it until it gets thicker (OR should I have a longer magnet and coil with a long stack of magnets inside)
- i notice the resistance on my coil is 60ohms, should I move to a thicker magnet wire to shrink this (or will that be at the expense of
more turns)

separately, it terms of how to "let it charge" before discharge (i.e. three shakes), could I use a

transistor, which triggers after the capacitor hits 2V? Does this make sense? attached is a rough idea with transistor in middle.

Or is there any other way to do this?

thanks so much, this is great.

 

[Externet]

The generation needs is not about Volts from the magnet/coil interaction. It is about Joules or wattseconds. Do not think 3 shakes will be enough, but try and come back with findings.
"Highly powerful" magnet and coil means yes, neodymium magnets, coupling and matching.
Your second schematic needs a supercapacitor in series to a diode to prevent self-discharge into the coil.
And having to shake for ten seconds to get a couple of seconds of light may not be ideal. Shaking it for minutes to charge a supercapacitor maaaaybe fits the purpose. A kids capability to perform the energetic generation requiered may diminish expectations too.

----> https://www.instructables.com/Shake-Flashlight-1/