Where to install a Capacitor

frogman1206

Member
I have a Diatone Tyrant 180 that was a PNF setup. A great little machine for a PNF when flying on 4S.

I bought it from an online retailer I have become friends with. The owner offered to upgrade my ESCs to Little Bees 20amp. He was replacing them on his racer and offered to give me and even install them on my Tyrant as a free upgrade. Of course I was all over it.

He did tell me I would need to install a capacitor since the Little Bees create voltage spikes that can toast your VTX for the FPV. The stock ESCs that came on the Tyrant had small capacitors installed on them but they seemed fragile just hanging out of the ESC in the open. The new ESCs don't have them. He told me a 1000uf 35V capacitor would do the trick. He mentioned to just solder it to the pad where the battery connections mounts to the board.

Is this the right place? It seems that would not be absorbing the spikes downstream but at the battery. Seems to me it should be somewhere on the PDB nearer the VTX plug? For testing he just wired the VTX off the balance plugs to alleviate the problem. I would rather not have to do that. I can get the capacitor and solder it on but want to make sure I put it in the right place.

Any help would be appreciated.
 

Peterev

Member
Hi,

What VTX do you have and what maximum voltage will it accept?

I have 2 quads, soon to be 3, that run on Littlebees and have never had an issue.. I wonder how an opto ESC could cause a system voltage spike that threatens the VTX?
 


ESC's have a capacitor on the battery side to smooth out voltage spikes going to the FET's. I would find it very odd that you have to add your own capacitor because the ESC doesn't come with one already. If you are running a BEC from the ESC to supply the power to your VTX then I could see the basis for the comment to add one but I still don't see the need. The voltage supply to your video transmitter can be "noisy" and this will affect the video signal and cause a poor picture in your goggles/monitor. If you are powering your VTX from the ESC this "could" be a problem. If you are powering you camera or transmitter from the battery directly it probably wont be an issue (but still could be). They do make an "LC filter" that provides a cleaner power supply to your FPV system if you have a problem with static in your video feed. Its important to know what voltage your VTX can accept. Don't just hook it up to the battery without knowing.
 

This is a known problem with little bee escs, they utilize a smd capacitor that is not up to the job. The voltage spikes happen when a motor is abruptly stopped during a crash. My suggestion would be to put a cap on the power input of the vtx, as they seem to be most susceptible to these spikes.
 

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