capacitordiyled
I've had this idea for quite a while, as I got the idea from The Stormlight Archive book series, in which they have marbles that glow. I have a limited understanding of electronics due to some intro to physics classes in college.
Does this sound like something that would work?
If you connect a capacitor to a resistor such as a small LED, and then in case it in epoxy, but then place it on a inductive charger such as a wireless phone charger, will the capacitor charge and then release light?
The issue appears to be the USB master going into thermal reset due to sustained high current draw. It could as well be resetting due to overcurrent protection, but that generally wouldn't kick in after 35 seconds but much sooner.
Caveat Emptor:
If the USB port simply cannot supply as much current as the device requires over a sustained period, neither of the two solutions below will do you the least bit of good. The resets will continue, at best with a longer cycle than 35 seconds, and at worst even faster because the capacitor charging trips overcurrent protection.
Simple solution: Hefty capacitor between +5V and GND lines. Start with a 4700 uF 12 Volt electrolytic (just because those are common enough, and inexpensive). If that doesn't work well enough, keep adding more.
More complex solution: An inductor-capacitor combination: Two hefty inductors, say 100 uH 1 Ampere each (just because those are common enough, and inexpensive), on the +5V and the GND lines, followed by a capacitor between them.
simulate this circuit – Schematic created using CircuitLab
The inductors will slow down the inrush current spike when the capacitor is charging up at power on. This prevents the USB port from going into overcurrent protection / reset.
What you've seen with two LEDs it is called an astable multivibrator.
It has two states that change whenever one of the capacitors is discharged.
Assume Q1 is ON. This means the positive side of C1 gets connected to ground. This leads to reverse charging of it (discharging), thus modifying the voltage at the negative side - it becomes positive and biases Q2 which turns ON. Q2 starts discharging C2 and it turns ON Q1 again. And this cycle repeats forever.
While either of the capacitors is charged, the base voltage of the transistor is negative, thus the transistor remains OFF. The frequency of this is related to the time needed for the capacitor to discharge (when it is connected in reverse polarity to ground via a resistor - e.g. C1-R2).
Source: Wikipedia - Astable Multivibrator
LED Flasher circuits usually work on the same principle.
Source: next.gr
When they have one LED, the other is usually replaced by a resistor.
Best Answer
Nope.
In order to receive the AC magnetic field emitted by the wireless phone charger, you need a coil. These chargers are basically high frequency transformers, except they're in two pieces with primary coil on one side and secondary coil on the other side, whereas the usual transformer is in one piece with both coils wound on the same magnetic core. But the principle is the same. So, you need a coil.
Also it is likely the wireless charger will go into some sort of powersave mode when there is no phone on it, which means it has a means to detect a phone, so if you want it to turn on, you'll probably have to fake this. For example the Qi wireless charging protocol is pretty involved, charger and device communicate, this needs a microcontroller, etc.
If you want simple, use fluorescent marbles and a "black light" emitter.
If you want LEDs, you could DIY a wireless power transfer solution. If you only need a couple mA to light a LED and don't care about efficiency, it will probably be much simpler than getting a microcontroller to talk to an off the shelf charger.