### Load Stage: Schottky Diode and Capacitor Adding a Schottky Diode and a Capacitor before the LED Load, since I've seen some variants of the circuit do this. It serves to rectify the pulses. Pumping that current into a capacitor smooths the output tremendously. ![[Pasted image 20250116074128.png]] ##### Output Waveforms **No Load:** ![[Pasted image 20250116073514.png]] **Direct to LED:** ![[Pasted image 20250115160212.png]] **Through Schottky Diode:** ![[Pasted image 20250115160220.png]] Obviously, with no load connected, the inductive kickback does what it does and destroys things (~200-600V). The LED creates a spike as well, but that spike decays quickly once the forward voltage of the LED is reached. Running spike through a schottky and into a cap makes the energy more useful. I imagine the selection of the schottky and the cap are very important here for efficient energy acquisition & retention. Low Vf, low ESR seem critical. Note that this means the load can't actually turn on from this point without charging the capacitor for a significant period of time. Another boost converter stage or voltage regulator may be necessary here. Once the capacitor is sufficiently charged, the LED will conduct again, around 3.3V/20mA. There will be a ripple on the rectified voltage, but it's something closer to DC than 50kHz inductive explosions. **Capacitor Output Voltage** ![[Pasted image 20250116074159.png]] **Inductive Kickbacks vs. Capacitor Output Voltage** ![[Pasted image 20250116074420.png]] Output signal is somewhere around 3.3VDC with a 25mV ripple. Not bad. At this point, it's time to start considering how to condition this signal to become a proper source for driving a LiPo BMS Charging Circuit. Since the power constraints are so extreme (<100mW), some kind of trickle charging methodology will be necessary.