In an attempt to reduce the all up weight on my FPV FunJet, I decided to try and power the FPV gear from the main battery, and thus being able to remove the 52 grams heavy 3s500 battery that I usually power it with.
This is my first attempt, a 1mH 1A inductor in series and a 470uF capacitor in parallel on the output side.
This worked OK, but there was some small lines still appearing during high current draw. ( You can see them in the beginning of this video)
After that flight I added a few extra small capacitors which got rid of the lines completely. But another problem came to light, I got less range. This is because the voltage of the main battery is often down at 10 Volts or so and the transmitter is made for 12V. That voltage difference is enough to make the transmitter loose output power and reduce the range. I still got good range, but not as good as I get from using a separate LiPo.
So I decided to scrap my homebuilt filter and order myself an AnyVolt micro, which is a step up/step down converter that can handle both voltages above, the same, and lower than the output, which is necessary for this kind of application.
It just arrived and I hope to be able to start testing it soon. Stay tuned!