Fat shark LC filter

[Col_M]

I just noticed that the Attitude SD goggles and VTx winding their way to me have a LC filter included in the box. Will I be OK to wire up my camera to the clean side of the filter along with the VTx?

I would have thought it';d be fine as the LC filter should be able to handle the extra current (I can';t imagine the camera draws much) and they are both 12V. It';ll just require making a modified loom to split the output of the filter to the camera and VTx.

Edit:
Also, do I need to connect the ground with the ';?'; or is that just for 5V cameras that are powered from the 5V rail from the VTx?


Thanks,
Col

[teslahed]

I would just put the low pass filter in between the battery and the camera and vTx exactly as you';ve shown in your diagram. You shouldn';t have a problem with the current.

I think the ground connection on your transmitter is just a pass through to make wiring things easier if you want to use it. As long as you have live and ground wired up to the video transmitter as shown in your diagram you';ll be fine; you don';t need to use it.

I made my own low pass filter the other day. They are just a capacitor in parallel and an inductor in series with the 12 volts output;

http://www.hobbyking.com/hobbyking/store/__26246__L_C_Power_Filter_for_FPV_A_V_Systems.html



I used a 16 volt 1000uF electrolytic capacitor and a simple ferrite ring inductor with about 8 turns of standard servo cable around it as well as misc bits of heatshrink to keep it all together. .

Bear in mind that the electrolytic capacitor used here has a polarity. If you connect it up the wrong way around (positive to negative) it will blow very quickly. You could put a diode in the circuit to protect the capacitor or else just do what i did - colour code your wires red and black and be careful wiring it up!

Low pass filters make a big difference. I';ve tried FPV without one - it';s not worth bothering.

[Col_M]

Perfect, thanks Chris! It';s good to get a sanity check when putting something together for the first time 

[nub]

this will be useful info for me thx

[fruitsalad]

So easy to make,the difference it makes well worth the effort..

[powerlord]

What values did u use for coil and cap ?

[fruitsalad]

one of these http://www.rapidonline.com/Electronic-Components/1000uf-25v-Radial-Electrolytic-Capacitor-11-3714/?source=googleps&utm_source=googleps&gclid=CP_Ql6z-4LcCFcKV3godIAkAlQ
and a ferrite ring and some old servo wire..

[powerlord]

Ah I see - old skool :-)

[powerlord]

What difference did it make ? I don lt get an interference. Until it starts to go with distance. Does the filter extend the distance or were you just getting noise on the video all the time without the filter ?

[fruitsalad]

was getting diagonal lines across my screen,the filter removed em..

[teslahed]

What values did u use for coil and cap ?

I used a 1000uF 16V low ESR capacitor i bought from here;

http://www.bitsbox.co.uk/capacitors/Low_ESR.html

low ESR capacitors are less likely to fail over time i believe. 16 Volts is enough for a 3 cell multirotor - if i was using 4 cells i would go up to 25 volts to keep some headroom for safety.

and a simple ferrite ring i got from here;

http://www.giantshark.co.uk/ferrite-rings-pieces-large-p-404727.html

which i wound with about 35 turns of not too thin copper enameled magnet wire. I haven';t measured the inductance though - my multimeter doesn';t stretch that far - so I';ll have to see how it performs once i have everything wired up.

I';ve covered it all in clear heatshrink - my version is very slightly smaller than hobbykings but i haven';t tested it yet.

hat difference did it make ? I don lt get an interference.

It filters out the interference from the ESCs and motors that would otherwise disrupt the video signal through the power cables. If you use a separate battery for your FPV system you wont need a low pass filter.