Build your own telemetry sensors.

[Nigel Dell]

Hi Chris have read the article with interest, I made various things for my Multiplex a few years ago so fancy another foray into electrikery, can you put me down for 6 boards please?

[PatMc]

Hi Chris, very interesting articles, they've whetted my appetite to having a go with Arduino. I've built a range of electronic projects starting with S/C valve Rx's & Tx's but never anything needing programming, this would be doubly interesting for me.
Can you put me down for 2 boards please.

[sgwlm]

2 boards for me please,

Arduino is brilliant, having these boards will make things easier.

[Chris Bott - Moderator]

Thanks everyone I'm so chuffed to see this amount of interest.

We'll just have to sit on our hands until they arrive, I'm so glad I placed an order sooner rather than later.

Is anyone making progress with a none PCB version yet?

Edited By Chris Bott - Moderator on 15/04/2019 14:52:14

[Chris Bott - Moderator]

It's always very difficult to include enough info in a magazine article, there's only so much space.

So here's some extra. I'm not sure how this will show up in a thread on different PCs/Tablets/phones but let's have a go. I can always chop it up into separate drawings if necessary.

This is the nearest thing I've done, to a full schematic.

[Andy Halmshaw]

Well I have taken the bull by the horns and built my first Telemetry Sensor. The results can be seen below, all quite straight forward but I did have to change a line in "oXs.config_basic .h" before I could get it to work.

// ***** 2.1 - FrSKY data *****

#define A4_SOURCE ADS_VOLTS_3

As you can see from the photos it appears to be working well, just need to add the heatshrink and I should be good to go.

[Chris Bott - Moderator]

That's great news well done Andy.

That line you refer to is commented out in all of my sensors because it enables a voltage reading called A4. But I use all the analogue inputs already for other things.

[Andy Halmshaw]

You are right, I changed the sketch back and it worked fine. I had Said it was all new to me and I thought "A4" was referring to the pin #. I will have to try and understand the coding a little bit better.

Is there a chance you could do a schematic of the XT60 with the sensor, I think I can make out the connections from the magazine artical but it would be nice to be certain.

Thanks again for all you are doing.

[Kevin Fairgrieve]

I am a follower not a leader with this kind of stuff.

Andy could you also do a schematic for yours, please.

I need to order a few sensors before I can go very far, but would like to be ready.

Thanks.

Kev

[Chris Bott - Moderator]

Kevin have a click on this picture. It will take you to some more info about this particular setup which looks very much like what Andy has built.

[Chris Bott - Moderator]

Posted by Andy Halmshaw on 17/04/2019 18:41:34:

You are right, I changed the sketch back and it worked fine. I had Said it was all new to me and I thought "A4" was referring to the pin #. I will have to try and understand the coding a little bit better.

Is there a chance you could do a schematic of the XT60 with the sensor, I think I can make out the connections from the magazine artical but it would be nice to be certain.

Thanks again for all you are doing.

This is what it's all about Andy, all of us learning about these things.

I'll dig the XT60 one out a little later and do more pics and a diagram.
If I remember correctly it was very non-linear until I added some extra resistors and re-did the calibration.
It will be useful to re-visit this one.

[Mike Blandford]

Andy: When adding heatshrink, make sure you don't block the holes in the pressure sensor.

If you just want to sense analog voltages, I have a simple project here (uses 3.3V, 8MHZ Arduino): **LINK**.

Looks like I built my vario sensor back in December 2015, after I had written the code for the SPort interface and the millis()/micros() that work without using interrupts so the software serial timing works reliably.

Mike

[Martin Harris - Moderator]

If any Jeti owners are feeling left out, this site may be of interest.  I've built quite a few of his sensors and they work very well in comparison to the pukka versions.

Edited By Martin Harris on 17/04/2019 19:57:11

[Chris Bott - Moderator]

Jeti owners won't feel left out as the OpenXSensors are easily configurable for Jeti, Multiplex and Graupner HOTT, as well as FrSky.

But that's an interesting link Martin. Thanks.

Edited By Chris Bott - Moderator on 17/04/2019 20:02:07

[Chris Bott - Moderator]

I can vouch for Mike's volts sensor project. In fact it might be ideal for use with the XT30/XT60 units as they just produce a voltage proportional to current.

[Chris Bott - Moderator]

Here are some close-ups of the XT60 unit. Black is the Gnd wire. Yellow is the voltage representing current and Red is the lipo voltage measurement from the potential divider that I added for that purpose.

[Peter Jenkins]

Posted by Chris Bott - Moderator on 17/04/2019 19:58:30:

Jeti owners won't feel left out as the OpenXSensors are easily configurable for Jeti, Multiplex and Graupner HOTT, as well as FrSky.

But that's an interesting link Martin. Thanks.

Edited By Chris Bott - Moderator on 17/04/2019 20:02:07

Hi Chris

Do you know if this will interface with a JR XG system? I have a brilliant little sensor pack made by SM Modelbau called UniSense E. They cost Euro 70 so I've only got one! It would be nice to build a few more but only if they work with JR radio kit.

Thanks

Peter

[Chris Bott - Moderator]

Posted by Peter Jenkins on 18/04/2019 23:37:13:

Posted by Chris Bott - Moderator on 17/04/2019 1

Hi Chris

Do you know if this will interface with a JR XG system? I have a brilliant little sensor pack made by SM Modelbau called UniSense E. They cost Euro 70 so I've only got one! It would be nice to build a few more but only if they work with JR radio kit.

Thanks

Peter

I'm afraid not Peter, no. Sorry.

[Alan Jarvis]

Chris

I am ordering parts prior to the boards coming. Can you give me the pin spacing for C1, C2.

[Chris Bott - Moderator]

Alan they are 5mm pitch spacing.

[Chris Bott - Moderator]

Just for those who haven't spotted it, I've sent out PMs to everyone who's expressed an interest in the PCBs.

If you'd like PCB(s) and don't have a PM, please shout up.

(PM = personal message. See inbox on top bar of this page)

[Andy Halmshaw]

I have now put heat shrink over the unit and as advised cut the sleeving away so that the two holes are not blocked. As you can see I have added a piece of "Open Cell Foam Rubber" because on the ground it was fluctuating up and down. Did seem to help but it did still fluctuate.

Can anybody with experience say if this is normal or am I expecting too much and do you have to mount the unit horizontal or is vertical ok?

When the wind subsides and I can go flying I will see how it works in a model.

[Martin Harris - Moderator]

One thing from my own experience to look out for with altimeters/variometers in electric powered models with lace-like firewalls is that there can be significant pressurisation of the fuselage. Looking at flights where the model had apparently descended significantly underground on the take off run - even after removing a large piece of covering toward the rear of the underside of its fuselage prompted me to make a sealed chamber plumbed to static vents for my Extreme Flight Extra.  Sensors in fuselages behind proper firewalls need no further precautions.

Is that an altimeter? I've never had problems with fluctuations on my own Arduino/BMP180 or BMP280 based sensors built from the link I provided earlier and simply ensured there was an air path to the vent hole. I followed Jeti practice and provided a small piece of U shaped card on top of the IC then covered it with heatshrink.

Edited By Martin Harris on 22/04/2019 18:37:20

[Chris Bott - Moderator]

Hi Andy

I put heatshrink over the whole unit and rely on slightly open ends.

I think if the heatshrink pulled tight over the face of the pressure sensor you'd have trouble, but otherwise it works well for me.

Over on this page it mentions making sure no direct light can get to the pressure sensor. There's other tips there too.

Mine are fairly stable, unless they get caught in any propwash during testing.

The only issue I find is that they need to settle after first being powered. So I turn on a model, do all my prefilghts and faffing about, then just before takeoff I reset the telemetry. This zeros the height reading.

Edited By Chris Bott - Moderator on 22/04/2019 18:40:04

[Kevin Fairgrieve]

All Arduino boards are not the same!!!!!

I bought a few a little while back and made the servo tester. Good results works well.

Today I spent a good 20 minutes trying to upload openXsensor to a board.

Yep you guessed it. The second set of boards I got were 328P and not 168`s, both were 3.3v though.

Now I have a couple of MPU-6050 3 axis gyro with accelerometer sensor`s which I got in for this project.

Would they wire up in a similar fashion to the pressure sensor?

Told you I was a follower...