Hi guys, 

Just wondering what LC filter you use on 4S rigs? 
And where do you use them (ie between the battery and VTX or flight controller)?
Do you use a 5v step down regulator from PCB to flight controller?

LC filter is used to minimize noise in the power, so it needs to be right before the vTX.
Some people use capacitors where the battery connects to the PCB to limit voltage spikes to all your gear.

In addition sometimes you will see smaller Caps on the power tot he ESCs. For example Little Bees have been known to cause some power spikes and some of the vendors actually send out a capacitor with them when you order a full set. They usually have a voltage on the cap but around 16volts and up your safe.

I use LC filter on all my quadcopters, and they have improved the video immensely.

But be aware some ESCs like the Little Bees with damped light enabled are the worst offenders in my limited experience, when it comes to noisy FPV video. I've got a few cameras that got damaged before an LC filter was fitted so they still demonstrated the same symptoms after I fitted the LC filter. I've also heard of manufacturing variations in VTX of the same type.

Apart from LC filter, you can also get a D-Sun reg with a cap on the outputs, not only does it regulate power going to the vtx/camera down to the right voltage but it cleans it up completely. I run my reg at 9v so it works on both 4S and 3S.

You can get the D-sun from lots of different places on the net, but yeah, I certainly recommend it over an LC filter. I found powering my VTX directly off the flight battery tended to overheat them and reduce their lifespan as well.

thank you guys! I already have a LC filter on order will give that a try first, failing that would get a voltage regulator!

In my last build i had an LC-Filter too.
Now with my newest build (http://intofpv.com/t-armattan-f1-6) i just got rid of it and what can i say.
Either it's the immersionRC vTX doing a great job or i'm numb. But it didn't change anything. Same quality of my pictures.

With an old Boscam vTX you could see the differences.

(05-Feb-2016, 02:03 AM)CurryCat Wrote: In addition sometimes you will see smaller Caps on the power tot he ESCs. For example Little Bees have been known to cause some power spikes and some of the vendors actually send out a capacitor with them when you order a full set. They usually have a voltage on the cap but around 16volts and up your safe.

This is absolutely true, I've had a VTX burn out because of surges from LittleBees.

Question - Will an LC filter or voltage regulator provide the same protection that a capacitor would from this kind of surge?

Yea, a LC filter is essentially a capacitor plus an inductor so in theory works even better than just having a cap alone

I hope you guys can answer this question then: I'm doing a 180-size build with LittleBees and an Aomway 200mw vTx.

The Aomway is rated up to 28V and I'll be running 4S. I was planning to supply the 4S pack voltage directly from the PDB to the vTx. The Aomway has a built-in regulator that supplies 5V to the FPV cam (I tested it with 14.8V in and yep, it produces exactly 5V), so I think the cam will be protected.

So… will the LittleBees produce spikes that go above 28V, and do the spikes affect vTx's as much as they do cameras? Do I really need an LC filter? I have one but there is no more room left inside the frame to put any more stuff!

From what I understand, the spikes are mainly caused by the fast switching transistors, and the voltage spikes don't normally go over the voltage of your battery level, but in fact it can drop a few volts below.

No matter what, I feel like a LC filter is necessary these days in most multicopter builds, not just to filter out noise, but to protect your electronics. Especially the motors and ESCs are getting more and more powerful and runs on higher RPM...

(11-Feb-2016, 09:39 AM)Relic Wrote: So… will the LittleBees produce spikes that go above 28V, and do the spikes affect vTx's as much as they do cameras? Do I really need an LC filter? I have one but there is no more room left inside the frame to put any more stuff!

I've burned out VTXs that were rated to 24v. Under normal conditions I don't think its a problem. However for me the issue was caused by a loose connection in the battery wire that caused all four ESCs to reboot several times in quick succession when I connected the battery, this caused a much higher voltage surge than usual, and burned out out the regulator. I just put LC filters or capacitors inline to anything coming off the PDB now as a precaution.