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Thread: Jeti DS-16 with TBS Crossfire

  1. #1

    Jeti DS-16 with TBS Crossfire

    Hi folks,

    I was just wondering if anyone who is using a TBS Crossfire radio link, also uses it with a Jeti DS16 (Or any other jeti TX for that matter)? I'm looking at powering the Crossfire from the Jeti TX, but the PPM output connector on the Jeti TX can only supply a 1s battery output at a maximum of 1 Amp, (i.e. 3.2-4.2v @1A max).

    Reading the specs on the Crossfire reveals it is rated to 3.5v, so it should work, at least for a portion of the battery life on the Jeti TX!

    Has anyone ever used the Crossfire on a single cell Li-ion or Lipo battery? Does it work okay, even at the higher power levels?

    Cheers
    Andy

  2. #2
    Navigator cracymarc's Avatar
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    why not use a external lipo?

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  3. #3
    Mainly because I'm looking for the most compact ground setup possible, for travelling with. The more batteries and stuff I have to remember to charge, and mount, the more complicated it is getting. Having a simple plug in module, that uses the TX power source, would be perfect for me.

    If it is not possible to power the TX from a 1s li-ion, then I shall more than likely go down the route of using a 2.4GHz repeater (i.e. Jeti RX in a box, connected to the Xfire TX, and with the ground monitor mounted inside too. Then I just have the one ground station battery to worry about.

    Andy

  4. #4
    Navigator plingboot's Avatar
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    I was wondering whether it was possible to tap power from the DS-16's battery…

    I drilled a hole in the back plate to mount the ppm socket and was thinking of having a second socket, next to it, for power.

    I emailed jeti and asked on one of the RCG Jeti forums about doing this - asking whether there are any locations on the circuit board(s) from which I could tap power, but received a pretty uninformative replies.

    I'll probably go down the route of adding a battery connector with a splitter. The only potential downside to this is the jack being permanently live (unless I install a power switch too) - tapping power from the board somewhere would be better as it'd only be live when the radio is on.

    It does seem like a lot of faff to do this, when velcro-ing a small lipo to the back of the radio would be the most straightforward solution, but I can guarantee that I'd either forget to charge it or forget to put it in the case.
    Last edited by plingboot; 13th April 2017 at 06:31 AM.

  5. #5
    I was under the impression that the PPM output connector on the circuit board of the DS-16, also had a 1A switched battery voltage (raw battery voltage) available? I was planning to use that. According to the TBS Crossfire specs, it draws 3.2watts at full 2W RF output. On a single cell li-ion, that equates to around 1A, so the only question is whether the Xfire is happy being run off of a 1s battery supply.

    I'm hoping to get a few hours tinker time this weekend, so will give it a test. If it works, it would be great. I want to make a new ds-16 back plate with a recess for the Crossfire, and all teh cables tucked neatly out of the way. I'll probably fire up the old 3d printer to make it...

    Andy

  6. #6
    Hot off the bench in my workshop: The TBS Crossfire doesn't like running off a single cell lipo. Well, for most of the time it doesn't anyway.

    I've tested mine hooked up to a bench power supply that has accurate current and voltage readouts. I turned dynamic power off, and set testing. At 5v input, the power drawing is 0.2A @ 10mW output. up to 1.04A at 2W output. (That's 5.2Watts input power).

    Drop the input voltage to 4v, and it still works, but draws 0.22A@ 10mw output all the way to 1.27A@ 2W output (still about 5.15Watts input power max).

    Drop it further to 3.6V, and the Xfire will work, but only on a power setting of 10mw. Any higher, and it moans about the input power, and doesn't transmit properly.

    So, whilst it might work for a short time on a single cell lipo that is fully charged (4.2v), when it drops below 4v, it will start not working properly.

    And in summary, powering it from the Jeti TX battery is not going to work properly. It needs more juice.

    I could run a small step-up (single cell to 5v @1A) converter off of the battery in the TX however. Not sure if I shall do this, or have a relay box somewhere...

    Andy

  7. #7
    Navigator plingboot's Avatar
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    Thanks for the update, using a step-up converter didn't cross my mind, but I do have a couple of Adafruit ones in the spares box - from a single cell project.

    Where abouts were you drawing power from (do you have a pic)? It's more than 18months since I last looked at this (had the back off the ds-16) but seem to remember the ppm cable only having 2 wires…

  8. #8
    For the bench test, I was using my variable power supply to see the sort of current draw. The PPM connector inside the Jeti TX, has four connections, so from the left, there is a PPM input (might be useful for connecting a head tracker or similar), A switched battery voltage (up to 1A available), a 0V, and on the right the PPM output.

    The switched battery output available at up to 1A, (effectively 3-4 watts) will not be enough to run the crossfire in terms of voltage, and depending on the efficiency of the step up regulator, it will probably not be beefy enough to run it at power levels above 500mW, possibly 1W if you are lucky.

    With that in mind, I would probably go for a feed straight off the battery connectors, and put a separate switch in for powering the Xfire module. I'm not sure if that would mess with the jeti electronics however....

    I'm actually thinking that the best solution now is running a relay station where the PPM output from a Jeti 2.4Ghz rx is fed into the crossfire, and both are supplied with power from a 2s lipo. It will allow the crossfire to be run reliably at any power setting, and can be tripod mounted to get the aerial in a good orientation (along with my VRx antenna).

    It's not as compact a setup for travelling though, so we shall see....

    Andy

  9. #9
    Navigator plingboot's Avatar
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    Umm… I've pretty much given up on tripods and ground stations for casual flying, got sick of lugging loads of stuff around and/or forgetting something important. I like being able to grab two cases with everything crammed in - one for the Gemini and one for the DS-16/goggles.

    I have also considered mounting a second lipo inside the DS-16 - specifically for the crossfire - but i'm a bit twitchy about charging it in situ like that.

    The answer might be a crossfire Tx with a built-in, rechargeable lipo.

  10. #10
    That's sort of my idea. One case for my Jeti tx. Another for my ground gear, monitor, aerial, xfire relay etc. Possibly even one case for everything...

    I do wonder if using a 2s lipo in the jeti tx, with a regulator to drop teh voltage down to 4v to supply it, is a good idea. I'm thinking not, because the ability to easily see the tx battery state is lost.

    At least with using a relay, I can use one channel of a rex3 receiver to generate the ppm output to feed into the Crossfire module, and another channel on the Rex3 as an input for a voltage sensor for checking the relay station battery status...

    Andy

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