Folks:

This is my first post on IntoFPV.

I've been flying micro electric helis, drones and fixed wing RC for over a decade but just got into FPV this year.

I prefer to fly fixed wing differential thrust toy planes like Airhogs and discovered that they can carry a small AIO camera/transmitter.

Here is some pics and a video of the plane I'm flying now:



More pics: https://twitter.com/John_Gardi/status/13...9879142408

Video: https://twitter.com/John_Gardi/status/13...8155919361

So here's the issue. I also carry an SD card DVR on the plane to record clearer videos (as you can see in the vid). This DVR will happily run at 1S 3.7 volts (though it's rated for 5 volts) but it fails if I hook it up to the plane's main battery when I throttle up the motors.

My solution is to carry a small 100mAh LIPO to power the DVR (the camera and its 25mW transmitter run fine on the 1S main battery). The DVR's battery doesn't last long but I can swap it out at least. I'd much rather have it all run off one battery if it's at all possible.

What's the solution here? How do I get a nice clean 5 volts out of 1S LIPOs?

I've ordered an LC filter and 3.3 volt to 5 volt booster and will probably try using a slightly larger battery. But what arrangement do I put the filter and booster in?

LIPO -> LC filter -> 3v-5v booster or LIPO -> 3v-5v booster -> LC filter?

I'd also like to try other receivers like Oscar's Backpack which has a built in microphone but needs 5 volts.

Hi Justatinker,

I have successfully used this Pololu 5V Step Up / Step Down Regulator S7V7F5   to power the video subsystem {combo Camera/VTX} in my 1s 85mm {frame} tiny whoops. What is nice about this regulator is that it maintains a constant 5 volts whether the battery voltage is higher or lower so it will work  with battery voltages from 2.7 to 11.8 and can easily be used on 1s and 2s applications.

Since a 1s is never over 4.35 volts you could just use a boost regulator. 

Also, these regulators provide good filtering so I didn't {and you shouldn't} need a separate filter. 

Are you running 1s due to the limitations of the flight controller and motor or is it purely a weight consideration? 

Now here is an interesting thought   ...use an adjustable regulator such as the Pololu Adjustable Step-Up/Step-Down Voltage Regulator S7V8A with the output set at 4.3-4.5 volts, run everything from it, and power it with a 2s LiPo battery. 
Just a thought 

I have used the Pololu regulators for about two years now and I find them to be very reliable and work as expected. They might be the cheapest, but they have always worked for me. 

Also, if all you have are 1s batteries, you can buy or make adapters to run them in series to make a 2s pack.

By the way, is that video from inside that model jet aircraft ??

+1 on the Pololu regulators, they're very high quality and well designed. In addition to their voltage regulators, they carry some excellent current sensors, barometers, etc that I've found useful for LR FPV setups.

For your purposes, this would likely be ideal:
https://www.pololu.com/product/2564
It's tiny (0.35″ × 0.45″ ) and only weighs 0.4g.

Cool setup btw! I like the cockpit view, and the DVR quality is surprisingly good for the size!

(01-Jan-2021, 10:55 PM)iFly4rotors Wrote: Hi Justatinker,

I have successfully used this Pololu 5V Step Up / Step Down Regulator S7V7F5   to power the video subsystem {combo Camera/VTX} in my 1s 85mm {frame} tiny whoops. What is nice about this regulator is that it maintains a constant 5 volts whether the battery voltage is higher or lower so it will work  with battery voltages from 2.7 to 11.8 and can easily be used on 1s and 2s applications.

Since a 1s is never over 4.35 volts you could just use a boost regulator. 

Also, these regulators provide good filtering so I didn't {and you shouldn't} need a separate filter.

Thank you for your informative reply. I did try using a step up power converter I hacked from a USB converter but it was noisy and still wouldn't run my DVR from the plane's main battery. It may not have had proper filtering.

Quote:Are you running 1s due to the limitations of the flight controller and motor or is it purely a weight consideration?

It wasn't so much a limitation, it was just what I happened to be using. I started out with a toy plane from Amazon that weighed 50 grams. The camera/VTX combo I got ran fine off the plane's battery. When I added the DVR, it would die when I throttled up the motors so I now carry a small LIPO to power it.

So my goal is simply to be able to power everything off one battery.

Quote:Now here is an interesting thought   ...use an adjustable regulator such as the Pololu Adjustable Step-Up/Step-Down Voltage Regulator S7V8A with the output set at 4.3-4.5 volts, run everything from it, and power it with a 2s LiPo battery. 
Just a thought 

A good thought! I am considering running everything of a 2S LIPO. The extra current available might solve my DVR power issues.

I think I've even found a step down converter that I might be able to use. Would this work?

Quote:I have used the Pololu regulators for about two years now and I find them to be very reliable and work as expected. They might be the cheapest, but they have always worked for me. 

Also, if all you have are 1s batteries, you can buy or make adapters to run them in series to make a 2s pack.

Good idea, I may try adapting 1S LIPOs to test things out then I can pick up proper 2S batteries and balanced charger if it does.

Quote:By the way, is that video from inside that model jet aircraft??

Yes, it's from the pilot's seat of the plane. My goal was to give as much a pilot's view as possible, thus the control panel and hoop representing the canopy pillar.

(01-Jan-2021, 11:52 PM)V-22 Wrote: +1 on the Pololu regulators, they're very high quality and well designed. In addition to their voltage regulators, they carry some excellent current sensors, barometers, etc that I've found useful for LR FPV setups.

For your purposes, this would likely be ideal:
https://www.pololu.com/product/2564
It's tiny (0.35″ × 0.45″ ) and only weighs 0.4g.

Cool setup btw! I like the cockpit view, and the DVR quality is surprisingly good for the size!

V-22:

I see that Amazon actually has Pololu regulator at a reasonable price as well!

The DVR weighs less than 3 grams but draws 250mA during recording. I may have to go the 2S LIPO route with a step down converter to solve that issue of it failing when hooked up to the plane's 1S 350mAh LIPO.

It is a cool setup for park flying. I got the plane in September of 2019 and flew it line of sight. Last summer I got my first camera/VTX combo and hooked it up to the plane's battery which worked fine. I originally mounted the DVR to my goggles but the video quality wasn't very good.

To got the plane to fly with the DVR and a 100mAh LIPO to run it, I had to add two extra motors (I just wired them in parallel with the existing ones and it didn't blow the receiver  ). I'm hoping I can save mass by using a voltage regulator so I can ditch the extra motors or put two more powerful one on it now that I know it can take the load.

Here's a couple more pics of the plane (75 grams, 14 inch wingspan).

What LiPo are you using? A decent quality 1s LiPo should have no problem powering the DVR, 25mw VTX and two micro brushed motors. You could also look into a micro cam from a tiny whoop style quad to reduce the added weight. If the stock plane is 50g you should be able to keep the total weight with DVR under 60g. Do a quick search on Amazon for "nano VTX" and you'll find quite a few options for cam+VTX under 5g.

(02-Jan-2021, 02:46 AM)V-22 Wrote: What LiPo are you using? A decent quality 1s LiPo should have no problem powering the DVR, 25mw VTX and two micro brushed motors. You could also look into a micro cam from a tiny whoop style quad to reduce the added weight. If the stock plane is 50g you should be able to keep the total weight with DVR under 60g. Do a quick search on Amazon for "nano VTX" and you'll find quite a few options for cam+VTX under 5g.

My camera/VTX combo is less than 4 grams already. It was making the plane just a bit nose heavy so I moved the battery and receiver back closer to the centre of gravity. I installed my DVR and its auxiliary battery right on the COG so I could remove them when not needed without changing the COG (that's the electronics bay in the second pic above).

The battery is a 1S 350mAh, 1.30wh LIPO. No markings as to its discharge rate though. The VTX on the camera is only 25mw and it stays on til the battery's low voltage circuit kicks in.

On my next plane, I might use a separate camera and VTX so I can move the VTX to the COG as well.

(01-Jan-2021, 10:55 PM)iFly4rotors Wrote: Now here is an interesting thought   ...use an adjustable regulator such as the Pololu Adjustable Step-Up/Step-Down Voltage Regulator S7V8A with the output set at 4.3-4.5 volts, run everything from it, and power it with a 2s LiPo battery. 
Just a thought 

I'm liking that idea more and more.

The regulator would maintain a constant voltage for the plane's receiver and motors instead of continually dropping while I'm flying as well as giving me more VTX and camera options.

Also, the extra available current from a 2S LiPo would probably allow me to run the onboard DVR from the plane's battery. It'll cost me in flight time but improve overall performance.

It would even give me the option of hooking something up that's 2S powered as well like a Tarot OSD (if I could find one).

Would this step down converter work? It can handle more amperage (2A) than the one you suggested.


As far as onboard audio goes, I'll just get a VTX with a built in microphone and if there's no audio out through the Smart Audio line, I can hook up an external mic to the onboard DVR (which I already know works).

i had two of the one in green, both didnt work at all xD i will stay away from these cheapish becs with poti.

(04-Jan-2021, 10:45 PM)hugnosed_bat Wrote: i had two of the one in green, both didnt work at all xD i will stay away from these cheapish becs with poti.

Thanks for the head's up on that! I may have to go with the Pololu power converter iFly4rotors suggested then, though it's expensive.

Could you recommend any other good power converters to use?

The smaller and lighter, the better. I probably wouldn't need more than 2 amps load capability.

(01-Jan-2021, 10:55 PM)iFly4rotors Wrote: Now here is an interesting thought   ...use an adjustable regulator such as the Pololu Adjustable Step-Up/Step-Down Voltage Regulator S7V8A with the output set at 4.3-4.5 volts, run everything from it, and power it with a 2s LiPo battery. 
Just a thought 

I did some testing on my plane's receiver and motors (2 x 0716 coreless).

It turns out that they only draw 200mA at full throttle. That's well within the 1 amp capability of the Pololu converter.
I found it on Amazon for $30, more expensive than the receivers and cameras I'm looking at but since you say it works, I'll get it anyway just to save time and not reinvent the wheel.

I have some 220mAh LiPos from a pocket drone I can use a 2S test battery. I'll also order some connectors to make a wiring harness to hook them together. My plane uses a 1S 350mAh battery so I should get better flight times with a total of 440mAh from the two smaller batteries in series. That how it works, right?

One reason I really like the up/down converter is that I can then run my plane on both 1S and 2S LiPos using the same battery connector. I could use 1S for flying practice and 2S if I want to do recordings with the onboard DVR.

This is the one, isn't it? 

Hi justatinker,

Yes, the Pololu regulators cost more than a lot of others, however, I have used them a lot and not had any issues. For my money, they work as advertised and expected. 

Now, if you set the regulator for a voltage that the flight controller, the motors, and the video system can work with {let's say that is 5 volts} then you can use either 1S or 2S batteries for input. 

Yes, if you want a 2s, wire the 1S batteries in series.

(06-Jan-2021, 07:15 PM)iFly4rotors Wrote: Hi justatinker,

Yes, the Pololu regulators cost more than a lot of others, however, I have used them a lot and not had any issues. For my money, they work as advertised and expected. 

Now, if you set the regulator for a voltage that the flight controller, the motors, and the video system can work with {let's say that is 5 volts} then you can use either 1S or 2S batteries for input. 

Yes, if you want a 2s, wire the 1S batteries in series.

Great then!

The 'Flight controller' runs on 1S, the AIO camera/VTX is 3.3v to 5v and the DVR is rated for 5v but runs on 1S (on its 100mAh auxiliary battery). Since it's current that the DVR needs to run properly, I may be able to run everything at 4.2v to 4.5v as you suggested to not tax the FC.

Here's the 'flight controller'. It has 2 ICs and a few FETs (one of which had to be replaced when I fried it). One of the chips is a processor and the other must be the gyro (but I don't know which is which).

Sounds like a plan.

(06-Jan-2021, 09:08 PM)iFly4rotors Wrote: Sounds like a plan.

It's pandemic scrimshaw time anyways until outdoor flying season starts again here.

I do have a pocket drone to fly indoors to keep my reaction time honed. 

I'll look into getting a tiny whoop to play with as well, I already have the goggles.