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Jan 21, 2020, 11:14 PM
fly by night
BCSaltchucker's Avatar
OK for 2S testing, I ordered one of these bench power supplies

https://www.amazon.ca/UNIROI-Availab...0&sr=8-17&th=1

sucks these won't commonly do more like 50 amps or more for testing motors on quads and larger planes, but my main purpose is to see exactly what will run on 2S li ion packs on Nanogoblins. And 10amps is plenty for testing the oem motor. So many vtx say they need 7 volts., and even FCs like F411w say they need 6.5 volts minimum. But li-ion 2S packs can safely be drained to like 5 or 6 volts to use up their real capacity.
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Jan 22, 2020, 08:21 AM
400' + is where fun starts.
Martin Y's Avatar
Yea, I tossed a 12 Volt 100A supply 2 years ago. Used it for working on car amps. Makes me think I should have kept it.
Jan 22, 2020, 10:10 AM
Registered User
Do we know the amp draw of the new Caddx DJI VTX?

You could look into a step up regulator. I know every gram counts on sub-250 but these are 0.4g.

https://www.pololu.com/product/2116

Or this is able to handle a little more amperage at 1.6g.
https://www.pololu.com/product/791
Jan 22, 2020, 10:33 AM
Registered User
Quote:
Originally Posted by smackfpv
Notamed,

Interesting, I ordered the Dart 250 as well!
No plan yet as to what guts will be in it. What are you planning?

BC
That build looks good! Third one or second one?
Great minds must think alike .

Swapping in parts from my FoamTini.

Matek F411-Wing with a Caddx Tarsier for video.
EMAX 1306B 4000KV
Hope my coax cable shows up in time for the build, and I'll have to try to make some shielding for the Tarsier so it doesn't give me the same GPS problems as my FoamTini experiences.
Jan 22, 2020, 02:22 PM
I tell her RC is cheap !
carguy1994ca's Avatar
Quote:
Originally Posted by BCSaltchucker
yeah DJI is in the back of my mind. And now with a much lighter weight Caddx flight pack for DJI coming out, it becomes more compelling to me, as it could be built into a nanogoblin and still under 250g.

https://www.snhobbies.com/product_in...ducts_id=11610

So then a starter system would only cost me the $700 for the goggles and $200 for the Caddx DJI set. OK that is still a massive pill to swallow! Add in the TrueRC long range antennas too
Seems pricey to me. I got the Experience combo with goggles and 2 Air Units (AU = vtx + camera) for 929$ can. Granted there was a Holidays special but 900$ for only the goggles and one vtx that canít record HD seems expensive.
Jan 22, 2020, 02:24 PM
fly by night
BCSaltchucker's Avatar
Quote:
Originally Posted by notamedclosed
Do we know the amp draw of the new Caddx DJI VTX?

You could look into a step up regulator. I know every gram counts on sub-250 but these are 0.4g.

https://www.pololu.com/product/2116

Or this is able to handle a little more amperage at 1.6g.
https://www.pololu.com/product/791
thanks! I might try that too.

In the past I have had some issues with adding regulators though. Like not producing the voltage they promise. But Pololu units are usually good
Jan 22, 2020, 02:43 PM
Registered User
smackfpv's Avatar
Quote:
Originally Posted by notamedclosed
Great minds must think alike .

Swapping in parts from my FoamTini.

Matek F411-Wing with a Caddx Tarsier for video.
EMAX 1306B 4000KV
Hope my coax cable shows up in time for the build, and I'll have to try to make some shielding for the Tarsier so it doesn't give me the same GPS problems as my FoamTini experiences.
Yup!

Oh, you did use the Emax motors? How have they been for you?

Most likely a RunCam split or Caddix Turtle v-2 that I will pull from a 7" quad. Might not even go HD and just put a DVR behind the camera.
Motor will be either a Racerstar 1507-3600 or a LDARC 1806 -2500 (overkill).
Matek wing or may use an Omnibus F-4 I have here just slightly used.

Have had good success on a few builds now wrapping wires and blocking the camera with a metal foil tape. It has eliminating interference on a ZOHD Dart 635 that was really severe when I first tried it.

Any recommendations on micro 4 to 6 gram servos? Have not had any success with them on builds and always end up using 9 gram units as they just work.
Jan 22, 2020, 02:54 PM
Registered User
Quote:
Originally Posted by BCSaltchucker
thanks! I might try that too.

In the past I have had some issues with adding regulators though. Like not producing the voltage they promise. But Pololu units are usually good
That's because they usually lie about their output capability, or more accurately their output capability is severely diminished the more the regulator has to change the input voltage.

I'm not EE but there are a lot of factors on exactly how much a regulator can push out, heat being the main one. BEC's are usually labelled showing what they are good for in terms of amperage output, but you'll notice the Pololu one only mentions max input amperage, not output because it's the input that matters.

So a step down going from 12v to 5v can handle 3 amps lets say, but if you give it 6S regulate to 5v it now can no longer handle 3A and will only realistically be able to handle 1A before thermal protection kicks in.

If my understanding of the Pololu documentation is correct then:

The DJI Air unit lists input power as 7.4-17.6 V, about 4-9 W.

That should be .45A to 1A at 9V (I guessing thats the difference between 25mw and 700mw transmissions).

So if the Caddx Vista is similar and needs 1amp at 9V then that is 9 W of power.

If our input voltage is 8.4v then the input amperage will be 1.1 A.

At 5v input the amps are 1.8A (or probably a little higher because they are not 100% efficient).

So you would want to the bigger, more powerful, step-up I had listed in that case. It's maybe a little dangerous still as voltage sag actually draws more amps as the regulator has to step up further. Also it warns you against going past double the input voltage...so if you sag to less then 4.5v you will be at a high probability of losing your video. Probably wouldn't risk it on a quad or non-inav airplane.

Edit: Oh, just realized something...you would be better off outputting as low as you can. If you drop your output voltage to 8.4 (theoretically your max input with 2S) you would gain a little breathing room. Also it says not to exceed the output with the input, but you could always try it. If you lowered to 8v or even lower to 7.4v (which I assume your flying voltage drops close to pretty quickly under load) you will have even more breathing room.
Jan 22, 2020, 03:04 PM
Registered User
Quote:
Originally Posted by smackfpv
Yup!

Oh, you did use the Emax motors? How have they been for you?

Most likely a RunCam split or Caddix Turtle v-2 that I will pull from a 7" quad. Might not even go HD and just put a DVR behind the camera.
Motor will be either a Racerstar 1507-3600 or a LDARC 1806 -2500 (overkill).
Matek wing or may use an Omnibus F-4 I have here just slightly used.

Have had good success on a few builds now wrapping wires and blocking the camera with a metal foil tape. It has eliminating interference on a ZOHD Dart 635 that was really severe when I first tried it.

Any recommendations on micro 4 to 6 gram servos? Have not had any success with them on builds and always end up using 9 gram units as they just work.
Motor has been good...it limits you for props though because it's a T-mount style. I can't find anything bigger then 3" for T-mounts. I was thinking of trying a 2S Li-ion pack but you need a 4" or 5" even at those voltages for this motor. So I'd have to change motors, but T-mounts are lighter then 5mm bolt mounts.

I use the ES9051's on my FoamTini and will transfer them over. They seem nice, but buy at least 1 extra. They have super tiny wires and I managed to fry one of mine. They also make kind of a high pitched whine but based on the tv show discussions going on here maybe most wouldn't hear them .



https://www.banggood.com/Emax-ES9051..._warehouse=USA
Jan 22, 2020, 03:55 PM
fly by night
BCSaltchucker's Avatar
those are some punchy motors for your Dart250

I just orderd a 1606 4000 for my old nanogoblin airframe. with a 30A Spedix and 4.5 inch tri prop. This will be for 4S operations and hopefully over 160kph speeds. The old airframe is too heavy now for sub250g flying, so I will rebuild it and laminate fully. And maybe install balsa elevons too (already has like 8 or 9g servos in it)
Jan 22, 2020, 06:09 PM
Registered User
smackfpv's Avatar
Awesome but damn they are expensive! I may stick to the 9 gram unit like these:
https://www.banggood.com/MG90S-Metal...r_warehouse=CN

These I have used in the past but can not recommend.
https://www.banggood.com/TowerPro-SG..._warehouse=USA
Jan 22, 2020, 06:49 PM
Registered User
Quote:
Originally Posted by smackfpv
Awesome but damn they are expensive! I may stick to the 9 gram unit like these:
https://www.banggood.com/MG90S-Metal...r_warehouse=CN

These I have used in the past but can not recommend.
https://www.banggood.com/TowerPro-SG..._warehouse=USA
$7?

Also not if you want to get in under 250g easily. It's 18g heavier for 2 of your MG90S servo's. I was amazed the stock setup goes with 9g but it's probably a cost thing too.

Servo's are one of those things I don't mind spending a little more on, and iNav recommends digital servo's. I have lost very few in my RC career and frequently reuse them when the model is ready to retire. I have stacks of those MG90's because unless I build a brand new plane instead of recycling I never seem to end up using many new ones.

So for iNav builds carrying expensive FPV gear, only the "best". Well, the best cheap option like Emax.
Jan 22, 2020, 10:25 PM
Registered User
smackfpv's Avatar
Quote:
Originally Posted by notamedclosed
$7?

Also not if you want to get in under 250g easily. It's 18g heavier for 2 of your MG90S servo's. I was amazed the stock setup goes with 9g but it's probably a cost thing too.

Servo's are one of those things I don't mind spending a little more on, and iNav recommends digital servo's. I have lost very few in my RC career and frequently reuse them when the model is ready to retire. I have stacks of those MG90's because unless I build a brand new plane instead of recycling I never seem to end up using many new ones.

So for iNav builds carrying expensive FPV gear, only the "best". Well, the best cheap option like Emax.
lol

I have a Tupperware container full of broken servos.
It happens when you push the limits or are a crappy pilot (I do both at times).
Funny though very few are metal gear servos. I do oversize them when I can as always have had better luck that way.

So 7 bucks each does add up. Though when you try to get sub 250, you gots to spend the cash!
Jan 22, 2020, 10:46 PM
fly by night
BCSaltchucker's Avatar
could go with high end DLG servos, lol . $50 a piece. I've considered it and have some on hand
Jan 22, 2020, 10:54 PM
Registered User
smackfpv's Avatar
Quote:
Originally Posted by BCSaltchucker
could go with high end DLG servos, lol . $50 a piece. I've considered it and have some on hand
Not an area I have done much review of, DLG's.

Why are they so expensive?


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