I got a 3.3V / 500mA Pololu for a glider-based FPV project I'm working on. I wired up the following harness last night, and although the receiver works fine and I read 6.6V on the VIN side of the Pololu, on the VOUT side I'm only getting 1.66-1.69V... so the camera won't run (it needs 3.3 - 5.5V).

I have tested the camera separately and confirmed it works... in fact it works amazingly well! Really impressed by the quality of the picture and the strength of the signal.


   

Now, I'm not electronics tech or engineer, but I have been active in the hobby for a long time (15yrs+) and am reasonably competent - or so I think anyways - at soldering. I tried desoldering and resoldering a couple times and got the same result with the output voltage.

My thinking: If it was a bad solder joint the first time around, I'd think the second I'd get a different result, but it was the same. Which leads me to believe that either the Pololu is shorted somewhere (that I can't detect) or that maybe I was accidentally sent one rated for a lower voltage?

Anything else I should try? I have a cheap RadioShack multimeter, can anyone give guidance on how to test this?

EDIT: Here is the Pololu I'm using:
http://www.getfpv.com/pololu-3-3v-500ma-...lator.html

It sounds like your camera/vtx needs more current than the Pololu can provide.

What camera/vtx are you using?

(01-Oct-2017, 08:26 PM)unseen Wrote: It sounds like your camera/vtx needs more current than the Pololu can provide.

What camera/vtx are you using?

I am using this one:
http://www.getfpv.com/lumenier-aio-adjus...tenna.html

Supposedly it does not need more than 350mA at maximum power. It worked fine when run directly off a 4.8V receiver pack, while running the radio receiver and a pan-and-tilt rig (headtracking, whee!) at the same time.

The Pololu I have was the one that GetFPV recommended (I called them) that I use with the camera, for whatever that's worth.

Thanks for the reply!

I'd have to agree that if the camera only pulls 350mA at full power, then the regulator should handle it. It'll get hot, but it should handle it.

I guess you have a dead regulator. What voltage does it give if you disconnect the camera?

Just tested that... it gives 3.28V with camera disconnected. Hmmm.

Got some resistors handy? You could load up the Pololu with an appropriately sized resistor and see if it can produce (say) 250mA without the output collapsing.

Something around 13 Ohms...

It would at least rule out the camera as the source of the problem.

I don't, but that's a good suggestion. I've dropped GetFPV an email to see what suggestions they have.

Thanks again!

I use these. They are cheap. You can adjust your voltage.
http://www.ebay.com/itm/272604581988

So GetFPV was cool and sent out a new Polulu, same specs as the first.

Unfortunately, I'm getting the same outcome as the first time around:

3.28V at the VOUT with no load

1.68V at the VOUT when the camera is connected.

I've attached another image of my setup - I just want to make sure I'm not doing something fundamentally wrong here?

Wiring looks correct. I know it is silly, but is your battery fully charged. Have you tested with higher voltage lipo?

Anyway, voltage sag is usually the VOUT is drawing too much current or the VIN is not keeping up. You can rule out VIN source by replacing the source with something like a PSU. If you still get voltage drop, then the camera might be drawing more power then you think.

Thank you for looking at the wiring and your suggestion. I tried it, and still got 1.68V at VOUT, after confirming ~12V at VIN. I guess this little camera needs a "more powah!"

Thank you!

I am using this super cheap and small stepdown to hook up Spektrum satellites. It is rated 800mha and works flawlessy. Vin 10v Max.
https://m.banggood.com/5V-To-3_3V-DC-DC-...33674.html

(14-Oct-2017, 09:11 PM)surfimp Wrote: Thank you for looking at the wiring and your suggestion. I tried it, and still got 1.68V at VOUT, after confirming ~12V at VIN. I guess this little camera needs a "more powah!"

Thank you!

It probably wouldn't hurt to measure the actual current consumption of the camera once you have something that will power it. If it's being sold as only consuming 350mA but actually consumes 650mA, the seller should update the specifications so that other people are not caught out.

650 mA for a micro aio cam seems a lot imho.
More than a 600 mwatt vtx? ?

(16-Oct-2017, 02:55 PM)lorentz Wrote: 650 mA for a micro aio cam seems a lot imho.
More than a 600 mwatt vtx? ?

The transmitter is 200mW maximum according to the link that surfimp posted, so I agree it does sound like too much. On the other hand, if the Pololu regulator is shutting down due to the current and the regulator is rated at 500mA, I can only assume that the camera is pulling more than the regulator can handle.

It's not as if Pololu has a bad reputation, so I'd trust their regulator board.