"Tearig,
We are building a test transceiver around the SX1272 as a possible replacement for the AT86RF212 (not compatible, of course) with matching for the US ISM 900mhz band only. I'll let you know what our field test results are (our application…"

"The LoRa system does provide really good receiver sensitivity if you use a high spreading factor.  The catch is that increasing the spreading factor also increases the data latency to a point where it may not be acceptable for real-time flight…"

"Sorry, the filename is correct but I copied the link from the previous post.
Version 2 UAVPWR file
I don't know what the APM 2.5 power system looks like, we use a custom autopilot."

"Design complete and files uploaded to http://71.6.151.114/pub/UAVPWR2.zip

Includes LDO for 5V regulated output, LC filter in input to LDO, mounting holes and BOM file with exact recommended part numbers.
Notes:
I don't think it will do much good to…"

"Jeff,  sorry, I forgot about that.  I will post another board in the morning with an additional regulated 5v output using the OKI switching regulator and an additional LC filter on the output to limit noise into the digital/sensor section.

Dean"

"Design complete and files uploaded to http://71.6.151.114/pub/UAVPWR.zip
Contains PCB Artist (free download) CAD files and PDFs of schematic and board layers.

Dean"

"It would not be wise to use diode drop to generate a regulated 5V anyway, as the drop depends on the current flow across the diode and can be much smaller than the rated 500 or 700mv value at low currents.
It would seem to be a good idea to put a 5V…"

"I have a tube of LTC1473's which we no longer use in product which looks like a good candidate for the board.  It does require a small inductor to generate the gate drive for the NFETS, but that is a cheap part.  I will post a schematic and board…"

"I will take a look at the available chips and design something over the weekend.  I don't think the 4415 is suitable, as turning off inductive loads (like servos) will produce spikes that exceed the 5.5V limit on the 4415, probably resulting in…"

"In Diptrace, the easiest way to export to PDF is to install a PDF printer driver (CutePDF, etc) and just print the schematic and both sides of the board.

When you say the other model of chip, which chip are you referring to?  Many of the linear…"

"Link restored.  Make sure you read the comments about inductive loads exceeding the voltage rating of the LTC4415.
Dean"

"You might want to get a Rocket RM900 instead and remove the board from the case for a UAV.  It is a little big, but transmits at 28dbm with two mimo transmit channels and there is a serial connector (ttl level) on the board.  The firmware SDK/source…"

"Robert:  Yes the switchover will be automatic.  You could use diodes on the input if you are paranoid, the voltage drop there will not make any difference to the outputs and that will absolutely prevent a shorted (or reversed) cell from taking down…"

"Switching regulators used to be much more noisy, but as switching speeds have gone up, the noise have dropped for a given inductor and output capacitor size.  Also, now that switching speeds are high enough the output cap can be a low esr ceramic…"

"My bad, I forgot about the minimum operating voltage.  The OKI-78SR regulators are pretty bullet proof and can be or'ed (will startup with a bias on the output).  How about just using two OKI-78SR regulators (one from each battery) and wiring the…"

"I have done a board for two LTC4415s and an OKI-78SR-5.  This provides one battery input (7-36V) and one BEC input with a single BEC output.  The board is 1x1" and contains surface mount parts.  The LTC4415s are around $4 q1 and the OKI regulator is…"