MiniHub+ - S.Port Telemetry Hub for Frsky Radios - Page 3 - RC Groups
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Aug 10, 2017, 09:45 PM
Can it fly? I'll try and see!
ryane67's Avatar
Quote:
Originally Posted by brtman
I'm not using opto switch................
What are you using for an ignition kill?
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Aug 10, 2017, 09:47 PM
Registered User
brtman's Avatar
bec port off my x24
Aug 10, 2017, 10:22 PM
Can it fly? I'll try and see!
ryane67's Avatar
Quote:
Originally Posted by brtman
bec port off my x24
Nice, I did not realize that had the ability to have a channel-selectable BEC output..

My resolution to the problem is to only hook the signal line up to the minihub.. though in that config if the battery is connected directly to the rcexl opto kill switch through its battery in port, I get some sort of odd square wave into the opto kill when the power to the system is off. I'm very confused at why that's happening.

On the plus side I would rather just run power out of my rx for my ignition kill, so I re-wired the kill switch to get its input power from the rx. There's still a miniscule amount of power into the ignition when the plane is powered up, but only enough to barely light(still some sort of square wave pulse) the LED.
Aug 11, 2017, 08:44 AM
If it has wings it will fly...
ckleanth's Avatar
Quote:
Originally Posted by ryane67
it appears that the Rcexl opto kill switch works by switching the ground leg from the ignition box, not the positive.

as soon as I provide a gnd by connecting the minihub to the box, the electrons flow through this new ground instead of the one blocked by the optical switch.

Quote:
Originally Posted by ryane67
Now to my observations:

Temp sensor works perfectly, as expected, the same as if I were to plug in the temp/brushless rpm s-port devices I have.

I have a couple of voltage dividers but I don't see myself using them permanently as rxbat in my situation gives me the info I need. I'll hook one up to test it out though.

RPM sensing... it works... but....... it's somehow back-feeding voltage into my ignition module despite only using the signal and ground wire on the extension. This plane has an EME35, so their ignition module is an Rcexl piece that has the RPM output so I'm plugged into that with my 2-wire extension. As soon as I connect the minihub to the rpm output, the LED for my ignition kill lights up. not good
From tips section

Optical Kill Switch

I have personally used the Tech Aero Ibec Optical Kill switch, the Powerbox Spark Switch and the RCXel Optical Kill Switch. From all three I recommend the Tech Aero Ibec Optical Kill switch as it does not require a separate voltage source and provides protection on both the signal and the power side to your receiver.
All other Optical Kill Switches ideally require a separate voltage source to power your ignition as the power side is not filtered / protected. Personally and over the years I found that keeping the ignition voltage source between 5 to 5.5 volts and even if the ignition module is rated to LiPo voltage things just work if you operate within this voltage range. Any excess voltage above the minimum voltage required for the ignition to operate, will be discarded as heat from the ignition module electronics. And as it is highly desirable to have a reliable and functional ignition module, I generally use this rule of thumb with great success.
Now as expected most Ignition kill switches will disconnect the (+ve) positive / red lead that is an input to the ignition module but the ground (-ve) is still connected. This will result for the ignition module to stop providing the spark and the engine naturally to stop.
However some users of the old MiniHub+ had experienced issues with certain version of RCXel Kill Switches as these devices were disconnecting the (-ve) ground / black lead. This will have the same end result for the engine however the difference here is that in our case we use the “tacho” signal and ground lead into the MiniHub+ to get an RPM measurement. Although the RCXel Kill Switches v2 I have tested did in in fact disconnect the (+ve) positive / red lead If you happen to have a RCXel Kill Switche that does that on this occasion I would recommend using a BEC to output no more than 5v to power your ignition via a separate ignition battery. Do not connect the RPM (+ve) jumper on the MiniHub+ as then you would probably bypass the optical kill switch and keep providing power to the ignition via the MiniHub+.


Quote:
Originally Posted by ryane67
George, I'm hooking my first one up right now, and I got to wondering.. will this accept 2S lipo through the S-port? I read the instructions and it says not to put more than 5v into the unit anywhere.
yes


Quote:
Originally Posted by brtman
Had me spinning too.. I think we can go in through s-port w/ 2s, BUT not with sensors. Sensors and tach only running sig. and ground....... That's how I interpreted the manual
yes that is correct


Quote:
Originally Posted by ryane67
Yeah I saw both things in the manual and decided 'George is a 3d flyer, he's probably running these on direct 2s' and plugged it in.

Works.
answered above
Aug 11, 2017, 08:57 AM
Can it fly? I'll try and see!
ryane67's Avatar
George what do you think about my solution of just running the signal line from the tacho output to the minihub+ without the gnd?
Aug 11, 2017, 08:57 AM
If it has wings it will fly...
ckleanth's Avatar
Quote:
Originally Posted by ryane67
Nice, I did not realize that had the ability to have a channel-selectable BEC output..

My resolution to the problem is to only hook the signal line up to the minihub.. though in that config if the battery is connected directly to the rcexl opto kill switch through its battery in port, I get some sort of odd square wave into the opto kill when the power to the system is off. I'm very confused at why that's happening.

On the plus side I would rather just run power out of my rx for my ignition kill, so I re-wired the kill switch to get its input power from the rx. There's still a miniscule amount of power into the ignition when the plane is powered up, but only enough to barely light(still some sort of square wave pulse) the LED.
re the RCXel Kill Switch that disconnects the -ve wire, from wherever your powering the ignition, use a BEC to output no more than 5v to power your ignition (suggest a separate ignition battery)
Do not connect the RPM (+ve) jumper on the MiniHub+
connect the ground and then you should now have 5v tacho source signal but that now is ok

Id say easiest/safest way to tackle the ignition is using a tech aero ibec...
Aug 11, 2017, 09:00 AM
If it has wings it will fly...
ckleanth's Avatar
Quote:
Originally Posted by ryane67
George what do you think about my solution of just running the signal line from the tacho output to the minihub+ without the gnd?
it should not work without the ground. the fact you have a faint LED signal it appears you have a ground loop somewhere mate

try powering the ignition via a battery-> bec output at 5v and see if that works. this is how I setup a plane using a RCXel Kill Switch but in reality id use them as last resort
Aug 11, 2017, 09:08 AM
Can it fly? I'll try and see!
ryane67's Avatar
Quote:
Originally Posted by ckleanth
it should not work without the ground. the fact you have a faint LED signal it appears you have a ground loop somewhere mate

try powering the ignition via a battery-> bec output at 5v and see if that works. this is how I setup a plane using a RCXel Kill Switch but in reality id use them as last resort
Yeah I was thinking the same thing.. ground loop... that and/or the rcexl opto kill is not actually properly isolated.

It's funny.. I've got a tech aero ibec on my 87 extra shp, but it's got an older DLE55 so there's no tacho output. I've got to Y into the hall sensor instead on that one... maybe I'll wait to hook up telemetry until I get the GP61 in that airframe.
Aug 11, 2017, 09:48 AM
If it has wings it will fly...
ckleanth's Avatar
Using the y lead from the hall sensor is fine mate. Just make sure +ve is not connected (rpm jumper on the minihub) and output the ibec at 5v
Aug 12, 2017, 04:19 PM
If it has wings it will fly...
ckleanth's Avatar
Today i had a go plugging a minihub+ to a Horus running opentx2.2. I'm happily confirming it works swimingly not that i expected any different

Just plug the minihub+ with all sensors attached, then click the search for sensors. Adjust offset on voltage to suit the voltage divider ratio your using and your done.
Last edited by ckleanth; Oct 26, 2017 at 08:13 PM.
Aug 13, 2017, 07:17 AM
Can it fly? I'll try and see!
ryane67's Avatar
I decided to order a couple tech-ultra ibecs for my two planes currently running rcexl kill's.. it's clear these rcexl's I have are not fully isolated and I am not willing to deal with the hiccups that seem to be coming with it.

I'm also running a Horus on 2.2.
I did some experimenting with the same plane and no matter the configuration, the RPM seems to have a strange ratio/offset. I don't know if this is an opentx 2.2 issue as I do not have a transmitter on a lower version. blades - 1, multiplier - 1 is what Id expect the settings to be and Idle is showing ~4500 rpm(really idles at about 1650), full throttle it's showing 10500+RPM(really around 7200).

I changed the setup is as follows to do away with any possible ground loop issues for the above testing:
Ignition is isolated, battery hooked direct to ignition box, no optical kill. Hall sensor with a Y connection, one side going to the ignition box the other going to the minihub+ (gnd and signal only). Jumper is not on any pins. There is also a temp sensor plugged in, which seems to work fine. The last connection to the minuhub+ is the s-port to the rx.
Aug 13, 2017, 08:36 AM
hey whats burning?
metalbender4by's Avatar
Quote:
Originally Posted by ryane67
I decided to order a couple tech-ultra ibecs for my two planes currently running rcexl kill's.. it's clear these rcexl's I have are not fully isolated and I am not willing to deal with the hiccups that seem to be coming with it.

I'm also running a Horus on 2.2.
I did some experimenting with the same plane and no matter the configuration, the RPM seems to have a strange ratio/offset. I don't know if this is an opentx 2.2 issue as I do not have a transmitter on a lower version. blades - 1, multiplier - 1 is what Id expect the settings to be and Idle is showing ~4500 rpm(really idles at about 1650), full throttle it's showing 10500+RPM(really around 7200).

I changed the setup is as follows to do away with any possible ground loop issues for the above testing:
Ignition is isolated, battery hooked direct to ignition box, no optical kill. Hall sensor with a Y connection, one side going to the ignition box the other going to the minihub+ (gnd and signal only). Jumper is not on any pins. There is also a temp sensor plugged in, which seems to work fine. The last connection to the minuhub+ is the s-port to the rx.
Most props have at least 2 blades. I would suspect that may be part of the problem. That should divide your numbers by 2 and get you closer to the expected rpm's.
Aug 13, 2017, 10:36 AM
Can it fly? I'll try and see!
ryane67's Avatar
Quote:
Originally Posted by metalbender4by
Most props have at least 2 blades. I would suspect that may be part of the problem. That should divide your numbers by 2 and get you closer to the expected rpm's.
It's a single magnet passing by the hall sensor per revolution of the engine.
from the manual:
Quote:
Telemetry Setup
If using Tacho/RPM Sensor
Scroll down in the Telemetry page until you find "Blades: X" and
set the number of blades for your application. Directly coupled
gasoline engines will be "1".
On the Telemetry screen, scroll down until you find where you
want to display the RPM data and then select it. Scroll down in the
menu until you find "RPM" and press enter.
2 blades directly divides the output in half, so I idle at 2250 and max out at a little over 5k.. that's just as useless.
Aug 13, 2017, 10:46 AM
Registered User
Quote:
Originally Posted by ryane67
it appears that the Rcexl opto kill switch works by switching the ground leg from the ignition box, not the positive.

as soon as I provide a gnd by connecting the minihub to the box, the electrons flow through this new ground instead of the one blocked by the optical switch.
The solution is to only wire the rpm signal and not the rpm ground. It'll get ground through the rcxl and when the rcxl is off, the rpm is zero anyway. That's how I got rpm working on an arduino running openxsensor with the exact same issue.
Aug 13, 2017, 11:02 AM
If it has wings it will fly...
ckleanth's Avatar
Quote:
Originally Posted by ryane67
I decided to order a couple tech-ultra ibecs for my two planes currently running rcexl kill's.. it's clear these rcexl's I have are not fully isolated and I am not willing to deal with the hiccups that seem to be coming with it.

I'm also running a Horus on 2.2.
I did some experimenting with the same plane and no matter the configuration, the RPM seems to have a strange ratio/offset. I don't know if this is an opentx 2.2 issue as I do not have a transmitter on a lower version. blades - 1, multiplier - 1 is what Id expect the settings to be and Idle is showing ~4500 rpm(really idles at about 1650), full throttle it's showing 10500+RPM(really around 7200).

I changed the setup is as follows to do away with any possible ground loop issues for the above testing:
Ignition is isolated, battery hooked direct to ignition box, no optical kill. Hall sensor with a Y connection, one side going to the ignition box the other going to the minihub+ (gnd and signal only). Jumper is not on any pins. There is also a temp sensor plugged in, which seems to work fine. The last connection to the minuhub+ is the s-port to the rx.
Hi mate. What voltage you power the ignition? Max voltage into the hub really need to be 5v max (which means the signal will have to be at 5v max)

Make sure you put 5v into the ignition without the Rexcel opto kill switch and hook up one of your other minihubs as a test.


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