Light balance with electromagnetic inductance
Hey everyone! I’m working on a “light balance” project that uses electromagnetic induction to power LEDs. The idea is simple: an emitter coil generates a magnetic field (driven by an AC source), and a receiver coil picks up the induced voltage, which we then rectify and use to light up LEDs.
The distance between the two coils changes based on how much weight is placed on the balance, which in turn affects the induced voltage and the number of LEDs that light up.
This is the circuit :
the component values are therefore wrong + Rcharge represents the LEDs
But, problem :
The induced voltage is way too low (max ~700mV), which isn’t enough to forward bias the diodes and power the LEDs (they need at least ~1.8V).
We’ve tried lowering the frequency from 200kHz down to 5kHz, increasing coil inductance from 10mH to 100mH, and improving coil alignment. Nothing seems to get us above 1V or so.
Plus, I am using LTspice for simulation but, there is one thing I do not understand (i'm a beginner in this field) : the voltage in the transmitter circuit is 10V, why is the voltage in the receiver circuit after L2 and C2 a few milliVolt ? Which is not enough to power the LEDs...
I have tried a lot of thing but i still struggle a lot.... Do you have any advice for me ?
How can we maximize the induced voltage?
- Is there a better way to boost the voltage after it’s induced (e.g., a simple transistor amplifier or voltage multiplier)?
- If LEDs are too demanding, what alternatives might be simpler to drive at lower voltages?
Any insights or advice from folks who’ve done similar inductive power transfer projects would be hugely appreciated. Thanks in advance!