Regulators

[Pisces]

I know this thread started out with the objective of finding a regulator for use with 4S packs...

What about 3S packs? I fly 3S packs almost exclusively with 12v camera and vTx. Up until now I've been powering cam and vTx with a separate 500mAh 3S, but I want to try the "one battery" approach. I am finding that when the flight battery gets low, applying throttle makes the picture go very dark and lose sync. Will the range video regulator give a constant 12v out if I give it a 3S input, all the way from fully charged (12.6) down to drained? I already made a sander-style LC filter, couldn't I just put the reg in line with it, ahead of the filter?

or could I simply use a step up converter?

Maybe this will help. I have been using a DC-DC boost converter to get regulated 12V DC for my FPV gear.

There are many DC-DC boost converter using the same National Semiconductor IC. The PCB are not all the same. Best to find a converter that has the better L-C filter at the output. For example this Ebay seller. Look for the output inductor on the PCB

http://www.ebay.com/itm/3-30V-4-35V-...item416472d09a

3S Lipo is fully charged at 12.6V. Discharged 9.9V. In practice the Lipo fully charged steady state settles to 12.4V. The IC boost chip needs a 1V drop to work. I have used 2 x diode at the input. 2 x diode drops the voltage 2 x 0.7V so is 1.4V. Then the DCV into the converter is 12.4-1.4= 11V. If the output is adjusted for 12V then the IC spec for 1V drop is within tolerance to work.

Any silicon general purpose diode rated 1 Amp or more will work ok for this mod.
The IN4004 is a very common diode.

I have used the converter to supply 12V continuous up to 800mA.

Attached photo show the DC-DC boost converter details. The DC-DC is lighter than a separate lipo for the FPV gear. The voltage is regulated +12V.

[SecretSpy711]

That is a clever way of doing it. I am familiar with diodes as I used them to step down the voltage when I converted my RC TX to LiPo. Looks to be about the same size as the SEPIC converter though. Are there advantages to doing it this way?

[volto]

Good idea pisces, this is much better than purchasing the more expensive SEPIC type dc/dc regulator, unless you plan to use 4s or higher.

[GregSilver]

Greg, that's not working. At least not with the cam and tx I have. I need some kind of reg, otherwise picture is unflyable when the battery gets low.

change your equipment. unless you are flying below safe levels, this should never happen. fly with hardware that is known to work...thus not re-inventing the wheel.

[SecretSpy711]

Greg what vTx do you use? I believe I am using good equipment, the 400mW 1.3GHz from BevRC and the Sony SuperHAD II 600TVL camera. I may have just run the battery too low, and with the voltage sag from the motor caused the video to drop out. I'd still feel more comfortable using a regulator when running everything from a single battery, though.

Pisces, the inductors I'm used to seeing look like a donut with coils of wire around them... Is there one on the board you linked to? I do see one here, however.

[Martinba77]

Hi SecretSpy711! Do some edit on the Pisces picture to show you where is the L-C on the board...hope that helps.

Hope you dont mind Lindsay.

Regards

Martin

[GregSilver]

99% of the people that use a single battery setup don't use a regulator. Why add the extra equipment when it is not needed?

There is no point, except to added unneeded equipment.

[Pisces]

I had a severe interference with one of my cams. The DC-DC was the only way I could stop the ESC noise from interfering with the CAM on this model. Black spots in the Video was fixed with the DC-DC.

FPV shops sell 12V DC-DC.

All my FPV grear is 12V. Vtx, OSD, CAM. I connect the DC-DC to the AUX Batt input of the OSD.

After the ESC shuts down on low batt and will no longer run the motor the DC-DC will keep 12V on the FPV gear until the flight batt is very low V. Like 4V?? and still give 12V output for the FPV gear. Maybe then one can save the model with an emergency glide in landing.

Thanks Martin. Yes the inductor L is the ferrite core as you have shown. Sometimes DC-DC with this L-C filter are sold as "low ripple" The bigger inductor ( on the PCB marked 2R2 ). Note also the 220uF CAN capacitor is also part of the output L-C filtering.

[SecretSpy711]

That's exactly the reason I think a reg is a good idea. Greg I'm sorry, I just don't agree with you. I think the reg adds a degree of reliability. Maybe the 99% of people that fly everything from one 3S pack with 12v equipment just haven't figured out a good way to do it. Pisces & Dio just nailed it. For 5v its a no brainer. If one cell in your pack failed, you'd be SOL without a regulator.

[Dionysos]

Let us know how it went as soon as you get the stuff going

Cheers,
Dio