Hi, I've got a 5v board but only 6v regulators...   

I'll probably just order a proper 5V reg, but I though i'd ask if anyone knows for sure if it will fry at 6v or maybe just die slowly?

I checked voltage after wiring a 1N4002 diode in-line, but I only get down to 5.8v.

Thanks!

Use at your own risk. I am pretty sure there will be some component that can tolerate, but others will not.

I wouldn't risk it. Get a 5V regulator.
Even if it worked, it will put more stress on the LDO (regulators) on the FC and it will be more likely to fail.

Thanks for the advice...much appreciated.

So I got powered up an flying using a 5v 200 mA  (edit: it is a 500 mA) voltage regulator to supply 5v to the RAM pin/rail on my "Omnibus F4SD".   ...and at first, using 3S, had a few successful flights.

Oddly, when I swapped to a 4S battery, my Runcam Sparrow camera blacked out?  OSD remains displayed in goggles, but video goes black shortly after plugging in a 4S lipo.  I thought maybe my camera just crapped out, but when I switch back to 3S, stable camera image returned?

I think I'm probably cutting it close with only 200 mA  (edit: it is a 500 mA) reg to power the camera, receiver, and FC (VTx is on vbat) but it seems like if this were a bottleneck, something would brown out using either 3S or 4S battery.

I checked the voltage at the camera plug when connected to 4S to be sure it was getting 5v and not vbat; it was 5V as it should be.  (...and this shouldn't matter anyway because the camera is rated to 36v)  

Am I missing something?  Any thoughts?

200mA seems very little for a regulator. What is the exact regulator are you using?

oops, sorry, you are correct, not sure what I was thinking. It's 500 mA:

Diatone Micro BEC 5V 500mA ...from BGood

Since vtx is on vbat and camera on a isolated regulator I would shunt both the vtx ground and camera ground to get a proper reference between camera and vtx. You can also disconnect the receiver just to make sure that you are not pulling too much current. With a regulator if you apply more voltage source you will have to burn more energy into heat. More demand on current more heat energy burning on the regulator, it can get noisy.

Your regulator is 500mah on 2-3S, but only 200mah on 4S. You are probably drawing more current then rated, hence the brownout from the camera. Your Sparrow consumes 180ma at 5V.

The Sparrow and your FC can take lipo why are you using a regulator? I would connect RAM to VBAT. Run camera off VBAT. The FC has onboard 5V regulator for your receiver.

Thanks Voodoo. thanks Maiden F.

I ran the camera off the regulator thinking I might avoid some noise, but I'll try to wire it up to the battery.  I do have a capacitor in play.

If that doesn't work, I think I have another vtx with its own 5V reg...probably better filtering too.

Quote:Your regulator is 500mah on 2-3S, but only 200mah on 4S. You are probably drawing more current then rated, hence the brownout from the camera. Your Sparrow consumes 180ma at 5V.

@ Voodoo, what you are saying seems to fit what is happening, but I'm curious to better understand why a regulator would only pass 200 mA on 4S though... I don't understand this.  

@ Maiden F., before I rewire the camera, I'll try yanking the receiver and changing the ground too.

Yes Weedle, like Voodoo said, the fc can supply the 5v for the receiver so you can disconnect it from that regulator and use the fc output. About your question, I addressed it in the previous post. You are trying to lower from 16,8v to 5v, so to make it simple, in a basic regulator you're burning the excess 11,8v. On 3s you getting from 12,6 to 5v, so less dissipated excess energy. If you pull less current the amount of excess energy will also be lower so you can get away with it. As soon as you put more load on it, the regulator will get hot and even stop regulating. There are different type of regulation, more efficient, but the typical ones work like this.
So, take off a bit of load from the reg, ground both camera and vtx and I think you will be fine

(16-May-2019, 11:29 PM)Green_Weedle Wrote: Thanks Voodoo. thanks Maiden F.

I ran the camera off the regulator thinking I might avoid some noise, but I'll try to wire it up to the battery.  I do have a capacitor in play.

If that doesn't work, I think I have another vtx with its own 5V reg...probably better filtering too.




@ Voodoo, what you are saying seems to fit what is happening, but I'm curious to better understand why a regulator would only pass 200 mA on 4S though... I don't understand this.  

@ Maiden F., before I rewire the camera, I'll try yanking the receiver and changing the ground too.

It is just the specs that was published for this regulator. But I think it probably has to do with Ohm's law.
Watt = amp x voltage

If watt of the regulator is fixed, when voltage goes up (3S to 4S) the amp has to go down. This is my guess.

With current cameras and VTXs, I don't really worry about running them off VBAT.

Yeah what they said

Quick update...

Once I unplugged the receiver, the Runcam came back on line, so yeah, on 4S, the voltage regulator became amp-limiting, even though it worked on 3S...learned something.

I ended up doing as suggested and running the camera directly off vbat.  Picked up some noise (black diagonal lines?), but flyable.

Thanks again!

Have you consider putting in a capacitor?