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Old Aug 15, 2011, 06:47 AM
Martin - AKA mr.sneezy
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Originally Posted by Skree View Post
could this also be done to an eagletree type inline brushless motor speed sensor to replace the optical sensor? we really need that BL RPM sensor. designing/building an interface is way beyond my skills though. i'll have to hope frsky make such a sensor or someone with the skills does a interface
If the Eagletree BL rpm sensor has a regular squared up pulse output (one per rpm) then it might work with no real effort. It would be a matter of matching the signal level and supplying the right sensor power voltage if not right. Certainly could be possible...
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Old Aug 15, 2011, 07:25 AM
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Yep that's what I meant, I would appreciate a picture . Thanks PLMS!

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I see nobody answered this one (unless I missed it). If I get you right, yes if you use a DHT-U you need to get power and PPM signal from the module pins on the back of a module type TX, and wire it to the DHT-U.
You could use a 5 or 6 pin header plug for a few cents from a DIY electronic store instead of hacking up an old TX module.
If that sounds like what you asked, I can try find a picture of what I mean ?
Martin
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Old Aug 15, 2011, 08:33 AM
Martin - AKA mr.sneezy
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Originally Posted by msev View Post
Yep that's what I meant, I would appreciate a picture . Thanks PLMS!
OK, a quick picture or four. Sorry it's not as sharp as usual, my macro lens is off the camera at the moment.

The first two pictures are of the first matching size plug I laid my hands on to show you tonight. It's a standard 3.5" floppy drive plug ratted from a PC power supply. I bet you can find one around somewhere.
Only four pin plugs are needed (three connections to DHT-U only though), five is nice but one pin can hang in the breeze if it's all you have available. The colors shown are NOT in any significance for the job, just swap them around to suit (Red for Battery, Black for GND, Yellow for PPM etc etc). The plug pins (sockets) can be removed by pressing the barb on the side of the sockets while pulling the wire very gently. Reopen the barbs, then insert in the right order for JR or for Futaba....

The second pair of photos is a plug ratted out of a Toyota Soarer EMV, just happened to be nearby. I also often find them in old DVD players or even old VCR's. I bet you have one somewhere to open up and rat out
Martin
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Old Aug 15, 2011, 08:52 PM
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FrSky new sensors

FrSky lipo voltage sensor will be released quite soon, which can monitor voltage for each cell. Amperage sensor and RPM sensor for brushless motor will follow.
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Old Aug 16, 2011, 03:51 AM
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Do that quickly Mr.Wu, Corona is a threat...
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Old Aug 16, 2011, 05:04 AM
Martin - AKA mr.sneezy
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Originally Posted by michel49 View Post
Do that quickly Mr.Wu, Corona is a threat...
Corona a threat ? I must have been asleep lately...
They failed my last testing.
Martin
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Old Aug 16, 2011, 09:02 AM
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http://www.hobbyking.com/hobbyking/s...DplusCR8FD.jpg
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Old Aug 17, 2011, 03:27 PM
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I've investigated the temperature sensor for the FrSky hub. It appears to be a 100K (at 25C) thermistor. I found a spec of a 100k thermistor I could buy, it is
at 25 C: 100kΩ
at 100 C: 4.77kΩ
at 0 C: 352.4kΩ7
so I wired 100K to the pins and got a reading of 25, 4.7K and got a reading of 102, and 330K and got a reading of 5, so this looks to be the sort of thermistor to get if you need a replacement or extra sensor.
If anyone has any info on any of the other sensors please post it. In particular I would like to know what the electrical interface to the vario (altitude) sensor is. At 1 metre resolution this is not very useful to detect lift or sink, but could we amplify the signal from the sensor. I don't want 9999 m altitude, I'd be happy with 1999 m altitude with a resolution of 20 cm, then we could detect lift and sink with it.

Mike.
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Old Aug 17, 2011, 07:53 PM
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there is two three pin chips that take 5 volts in and has an output of

Linear +10.0 mV/C scale factor

This LM35 is 1mv per degree C.

Linear +10.0 mV/F scale factor

The LM34 is 1mv per degree F

So at 100F the LM34 output is 1.00volts
and at 100C the LM35 ouput is 1.00 volts.
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Old Aug 17, 2011, 09:40 PM
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The Eagle Tree RPM sensor works on 3-5volts.
Neal
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Old Aug 17, 2011, 10:13 PM
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Altimeter sensor is Bosch BMP085 according to PLMS's post. It is digital with I2C interface. I am trying the sensor with Arduino, it reads less than 1m but requires processing, at least filtering to get stable reading.
I am curious what FrSky hub processes this sensor input. If it already filters and sends altimeter value in meter, it may not be optimal for variometer use. On the other hand, I am flying How High RT telemetry for a few months as vario. It sends altimeter value in meter at only 2 times per second but it is usable as vario (though calculated audio vario sound is not smooth.)

Satoru
Quote:
Originally Posted by Mike Blandford View Post
....
If anyone has any info on any of the other sensors please post it. In particular I would like to know what the electrical interface to the vario (altitude) sensor is. At 1 metre resolution this is not very useful to detect lift or sink, but could we amplify the signal from the sensor. I don't want 9999 m altitude, I'd be happy with 1999 m altitude with a resolution of 20 cm, then we could detect lift and sink with it.

Mike.
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Old Aug 18, 2011, 04:12 AM
Martin - AKA mr.sneezy
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Originally Posted by michel49 View Post
Yep that one...
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Old Aug 18, 2011, 04:22 AM
Martin - AKA mr.sneezy
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Originally Posted by ssatoru View Post
I am curious what FrSky hub processes this sensor input. If it already filters and sends altimeter value in meter, it may not be optimal for variometer use.
That may be true. We don't know how they setup the sensor or filter it.
Both Renato and myself have tried a few things to get the best out of the sensor. Even with the internal oversampling turned on and some external averaging of the out we found that 1m resolution and 1m/s rate of change was the best we got. Unless Renato has improved the PIC code since then...

I think we both concluded that it was good enough for the job though, and considering the much simpler circuit and no adjustments needed (or calibration) I still would use it again.
I've done many analogue sensor designs, and got good results usually, but by heck the R&D time was FAR longer to get the circuits optimized and repeatable...
Martin
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Old Aug 18, 2011, 04:30 AM
VHO
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Armidale NSW Australia
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Originally Posted by ssatoru View Post
On the other hand, I am flying How High RT telemetry for a few months as vario. It sends altimeter value in meter at only 2 times per second but it is usable as vario (though calculated audio vario sound is not smooth.)

Satoru
Have been using How High RT set to feet = 0.3m sensitivity as a vario with voice output around a threshold setting. Works well, and it doesn't need the FrSky Hub..
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Old Aug 18, 2011, 04:48 AM
Martin - AKA mr.sneezy
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Originally Posted by VHO View Post
Have been using How High RT set to feet = 0.3m sensitivity as a vario with voice output around a threshold setting. Works well, and it doesn't need the FrSky Hub..
Hi Hutton. That sounds fairly good. Is the voice output something you home brewed ?
PS. You flying FrSky these days ?
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