Hello.
This is my first post in this forum, and I know very little about electronics.
I am currently using wireless power to light up a LED inside of a wooden sculpture.
So far I have been using matching components from a kit:
https://www.aliexpress.com/item/32944450041.html
The sculpture has a stand with the transmitting coil inside. The receiving coil will usually be in the most favorable position to receive power from the transmitter.
To do get this I take apart the receiving coil and the LED, and reconnect the coil to the LED through thin wires.
The coil have a tiny capacitor attached to it that I have been told is for resonance with the transmitter. I have also learned that the transmitter sends AC power, and that this is no problem for the LED to handle as it will just block half of the pulses and use the rest.
What I want to achieve is for the LED to turn on slowly when put in it's stand, and fade out slowly when it is taken off the stand.
I have managed to create a circuit that gives me the wanted effect, but the question here is how to make it safe, and what is the best components to use.
This is what I have done so far:
C1. I want to use a super-capacitor to delay the light up, and to store the energy. This is because of the high amount of charging cycles before replacement is needed. In my working example I use a 2.7V 0.5F super-capacitor.
D2. In order to use a super capacitor I have to turn the AC from the coil into DC, right?, so the first component I have added right from the coil (after the tiny resonance capacitor) is a Shottky diode 1N5819.
This is my circuit so far:
R1. I was told that i need a resistor before the LED, so I found some formulas and found that i needed on at 3ohm. Anyways I have tested the function with and without resistor, and it works in any case, but the question here is to find out what is safe since the whole assembly will be put inside a wooden sculpture.
L1 is the receiving coil shown i the photo. C2 is the tiny capacitor shown in the same photo. D1 is the LED in the same photo. All these three parts was the original receiving assembly.
Now to what I am wondering here.
1. The super-capacitor is made for 2.7V, but the voltage in this circuit is much higher. When I try to measure the voltage of the AC directly from the coil i get around 2V, but I don't think this is a correct measurement, because the measurement i get after adding the diode is up to 28V. I have measured this directly with my multimeter, but also indirectly by charging a 100V capacitor and taking measurements from it after i take it out of the circuit. The LEDs are rated from 2.2V to 3.6V, so this does not make sense to me. Could i destroy the super capacitor by charging it at this voltage, or is it just mye readings that are wrong for some reason?
2. I don't really know how to choose a resistor for this circuit, or if i need it at all.
When i test this circuit on my breadboard it works just the way I want, but the readings make me concerned about the safety. Maybe the capacitor and the resistor can generate too much heat over time closed inside the wooden sculpture? What is going on here with the voltages?
I have tested on my breadboard a lot, and no component ever gets hot to an extent where i can sense any heat with my fingers. Still these are critical questions because i sell these sculptures to customers who may have them connected to power day and night over years.
Can anyone help me to understand what is going on here?
This is my first post in this forum, and I know very little about electronics.
I am currently using wireless power to light up a LED inside of a wooden sculpture.
So far I have been using matching components from a kit:
https://www.aliexpress.com/item/32944450041.html
The sculpture has a stand with the transmitting coil inside. The receiving coil will usually be in the most favorable position to receive power from the transmitter.
To do get this I take apart the receiving coil and the LED, and reconnect the coil to the LED through thin wires.
The coil have a tiny capacitor attached to it that I have been told is for resonance with the transmitter. I have also learned that the transmitter sends AC power, and that this is no problem for the LED to handle as it will just block half of the pulses and use the rest.
What I want to achieve is for the LED to turn on slowly when put in it's stand, and fade out slowly when it is taken off the stand.
I have managed to create a circuit that gives me the wanted effect, but the question here is how to make it safe, and what is the best components to use.
This is what I have done so far:
C1. I want to use a super-capacitor to delay the light up, and to store the energy. This is because of the high amount of charging cycles before replacement is needed. In my working example I use a 2.7V 0.5F super-capacitor.
D2. In order to use a super capacitor I have to turn the AC from the coil into DC, right?, so the first component I have added right from the coil (after the tiny resonance capacitor) is a Shottky diode 1N5819.
This is my circuit so far:
R1. I was told that i need a resistor before the LED, so I found some formulas and found that i needed on at 3ohm. Anyways I have tested the function with and without resistor, and it works in any case, but the question here is to find out what is safe since the whole assembly will be put inside a wooden sculpture.
L1 is the receiving coil shown i the photo. C2 is the tiny capacitor shown in the same photo. D1 is the LED in the same photo. All these three parts was the original receiving assembly.
Now to what I am wondering here.
1. The super-capacitor is made for 2.7V, but the voltage in this circuit is much higher. When I try to measure the voltage of the AC directly from the coil i get around 2V, but I don't think this is a correct measurement, because the measurement i get after adding the diode is up to 28V. I have measured this directly with my multimeter, but also indirectly by charging a 100V capacitor and taking measurements from it after i take it out of the circuit. The LEDs are rated from 2.2V to 3.6V, so this does not make sense to me. Could i destroy the super capacitor by charging it at this voltage, or is it just mye readings that are wrong for some reason?
2. I don't really know how to choose a resistor for this circuit, or if i need it at all.
When i test this circuit on my breadboard it works just the way I want, but the readings make me concerned about the safety. Maybe the capacitor and the resistor can generate too much heat over time closed inside the wooden sculpture? What is going on here with the voltages?
I have tested on my breadboard a lot, and no component ever gets hot to an extent where i can sense any heat with my fingers. Still these are critical questions because i sell these sculptures to customers who may have them connected to power day and night over years.
Can anyone help me to understand what is going on here?
