Student trainer mode

oiseau · Post by **oiseau** » Tue Jun 05, 2012 1:25 am

Hi, I have some questions about putting my 9x in student mode.

-Flysky 9x slave, er9x, HK backlight
-Spektrum dx5e master
-mono headphone cable, original Spektrum

I don't have the Spektrum box yet, but I would like everything to "just work" when we get to the field. I read that this setup should work fine, with no extra stuff. However, I read that some people are having trouble with the HK backlight, but some people say the problem is only with old versions of the backlight. I read that Spektrum has a different channel order - not an issue thanks to er9x. I read that Spektrum outputs a lower-voltage PPM - supposedly not an issue because the 9x is the slave box. I read about the "resistor fix" - supposedly not an issue because I can remove the radio module.

I noticed that my 9x starts up when the buddy box cable is plugged in, though the backlight stays off. There's no indication otherwise that it's in slave mode - should there be?

From all the searching I've done, I appear to be only one of few that uses his 9x as a slave to another brand radio.

So, should everything "just work?"

Thanks for the help!

Post by **Crucial** » Tue Jun 05, 2012 5:41 am

I used my er9x radio in a similar setup a week or so ago. I slaved it to a Dx8. I used a mono buddy cable and didn't need to do anything else. You should leave the radio off when you plug the cable in and it will automatically turn the radio on. You wont have the normal beeper or backlight functioning as the slave only powers part of the system.

If you have the latest version of the firmware installed you don't need to take the module out to connect as a slave. You just have to enable the PPMSIM setting in the radio settings and the model settings.

Post by **Kilrah** » Tue Jun 05, 2012 7:17 pm

oiseau wrote:I noticed that my 9x starts up when the buddy box cable is plugged in, though the backlight stays off. There's no indication otherwise that it's in slave mode - should there be?

This is normal. The "Slave" indication will show up if you go to the trainer setup screen (LONG LEFT -> right to go to screen 2/6).

oiseau · Post by **oiseau** » Tue Jun 05, 2012 10:31 pm

Crucial, thanks for the reassurance. Kilrah, I didn't know that, it seems to work. Thank you!

gohsthb · Post by **gohsthb** » Tue Jun 05, 2012 11:16 pm

I've updated the trainer section of the wiki.

http://openrcforums.com/wiki/index.php/ ... or/Student

-Gohst

Post by **ShowMaster** » Wed Jun 06, 2012 12:02 am

What if the Spektrum is the trainer/slave and the 9x er9x is the master? Not so easy?
SM

oiseau · Post by **oiseau** » Wed Jun 06, 2012 3:02 am

ShowMaster wrote:What if the Spektrum is the trainer/slave and the 9x er9x is the master? Not so easy?
SM

From what I understand from other threads in this forum is that Spektrum puts out a 1.5v signal which is too weak to be understood by the 9x processor without additional circuitry.

Post by **ShowMaster** » Wed Jun 06, 2012 5:30 am

Yes, I ran into that and used a 1 transistor circuit by Gruvin to fix it. I've tried to make the circuit work externally. It have up after a few tries. I may try it again as time permits. I brought it up just go get some fresh ideas on making it work.
Thank you for the 1.5v value.
SM

gohsthb · Post by **gohsthb** » Wed Jun 06, 2012 1:15 pm

Showmaster,
The external circuit should only need a simple transistor and a resistor. Trying this circuit in the simulator seems to be working just fine. In the other thread Mike B said Er9x auto detects the PPM polarity so it does not matter if the converter inverts the signal. His idea about using a diode doesn't seem like it would work though. I can't get the voltage levels to come out right with just a single diode.

In the circuit I have attached the 9x voltage source and Rpullup are internal to the 9x. The JR voltage source is meant to be from a JR/Spektrum radio. Q1 and R2 would be the circuit you need to build inline.
-Gohst

oiseau · Post by **oiseau** » Wed Jun 06, 2012 2:17 pm

Gohst, can you post a picture of where to solder the collector of the NPN? Does the emitter go to the PPM-in pin?

Wouldn't this circuit block the ability to use the 9x in student mode?

Post by **cre8tiveleo** » Wed Jun 06, 2012 2:42 pm

emmiter is always with an arrow (shows the 'flow' of electrons'), the collector is without an arrow, base is the 'top'... little triangle usually means ground... electronics 101.

Post by **Crucial** » Wed Jun 06, 2012 3:23 pm

Oiseau, here is a link with different electrical symbols and their descriptions

http://www.rapidtables.com/electric/ele ... ymbols.htm

Post by **ShowMaster** » Wed Jun 06, 2012 3:32 pm

First off thanks for the circuit. I'll wire it up ASAP and give it a try. I've been installing the internal circuit in the builds for club members but would rather not. Many are coming from a Spektrum tx to er9x Frsky for the upgraded features for their main tx. The Spektrum becomes the trainer tx. The downside with the internal mod is it defeats the new menu options MikeB added so external has peaked my interest again in a working circuit. I got lazy and busy and never followed through on my design so I welcome the help.

About "current flow" in electronics.
If you use conventional current flow notation (+ to - flow) then current does flow with the arrows in semiconductor circuits. This is my choice of current flow but not actually what's happening. I call it "hole flow" since electrons flow by bumping into each other with a hole between them. If the electrons are bumping/ moving one way (- to +) then the holes are moving the other way (+ to -) with the arrows.
In the scientific true current flow world current flow, electron flow is - to +. This is called "electron flow notation" and it's what's actually happening.
In the end use what ever works for you but to be "technically" correct remember that the electrons flow against the transistor and diode arrows and go from the battery - to +.
I brought this up only because many working on their 9x mods have no real electronics or schematic reading background and are actually taking the electronics "101 course" for the first time by reading our post. Not everything can be presented in a picture showing the real wires and parts, sometimes the schematic drawing is the only way and reading it can be confusing but overcome with a little help.

This was meant to be constructive in nature nothing else.
SM

gohsthb · Post by **gohsthb** » Wed Jun 06, 2012 3:33 pm

That circuit is meant to go in the trainer cord. So you would need to at least have to cut an existing trainer cord. The collector of Q1 would be wired to the end of the mono plug. And ground would be hooked to the other part. On the other side of things the end of the mono plug would get connected to R2.
Now that I have thought about it a little more I think 1 more resistor should be added on the collector side. This is just to save the hardware, should the 9x try to output 5V on the trainer port and the student tx try to pull the line low at the same time. That condition would cause a short through the transistor, the extra 1k resistor would limit that current.
-Gohst

gohsthb · Post by **gohsthb** » Wed Jun 06, 2012 3:39 pm

I might grab a couple of mono jacks from radioshack on my way home. I also will wire this circuit up and test it. If it works like I expect it to I will take some nice pictures so everyone can copy the design. The schematic I posted wasn't meant for normal people to try and build the circuit from. It was something for the people that already know to test out and see if it works.
The round circles in my schematic are voltage sources. So the + and - are in the correct places. Normally they are labeled V(something) so it is easier to tell. I felt the need to show that they came from separate radios.
-Gohst

oiseau · Post by **oiseau** » Wed Jun 06, 2012 3:44 pm

Yes, thank you, but that's not what I was asking. I was wondering where on the backboard the collector is connected to. Apparently +5v is available. I haven't had a look at the 9x backboard yet, really I've only opened the transmitter to solder on the flasher. Also where the PPM-in line should be connected, since it is not in that diagram. Also semiconductors are not usually covered in first year electronics, except for op-amps and in that case only for studying gain. At least, where I'm from

Ah, new replies, thanks for the additional information, let me know if this is what you mean. I use LTSpice myself and I often use nonsensical symbols or leave out components on purpose if nobody else is supposed to see it.

gohsthb · Post by **gohsthb** » Wed Jun 06, 2012 3:57 pm

Yes just like that.
-Gohst

Post by **ShowMaster** » Wed Jun 06, 2012 4:31 pm

It's all good info. No confirmed by me but the trainer jack on the 9x may be a stereo jack? Mono and stereo cables seem to work. Some may have used the jack and added power as another circuit on it. My thoughts originally were to add a power source in the inline adapter level converter. This may or may not be needed to get the correct action on the output of the circuit. Best way is to wire it up later and try it. I also thought the Spektrum/JR ppm out is capacitive coupled and complicates things. Has anyone traced or actually have a schematic of the Spektrum or JR PPM output circuit?
I was given several JR TXs that were purchased to use as trainers to Dx7's by my club that won't drive the DX7. I've been asked to make them work so this external level converter idea has become important to me again. It could be used with many other tx combos for teaching.
SM

Post by **Kilrah** » Wed Jun 06, 2012 5:19 pm

ShowMaster wrote:No confirmed by me but the trainer jack on the 9x may be a stereo jack?

Yep it is, the middle ring is unconnected.
I have modded it to have power, and rewired as tip:+Vswitched, middle:ppm, sleeve:gnd to reduce the risk of shorts if the jack is inserted when power is on.

kaos · Post by **kaos** » Wed Jun 06, 2012 6:38 pm

Crucial wrote:Oiseau, here is a link with different electrical symbols and their descriptions

http://www.rapidtables.com/electric/ele ... ymbols.htm

woo! that brings back my 37 y/o memory.

forgot most of those except a few simple ones.

good refresh course.

I have been looking at the trainer/trainee (master/slave) things for a while. Before I got my head busted by all the circuit needed I found this : http://www.hobbyking.com/hobbyking/stor ... duct=18703
it should work for ALL brands in both ways without any circuitry.

not on micros for sure.

Post by **Crucial** » Wed Jun 06, 2012 6:47 pm

It may work but what happens when you are trying to take control and your student is still trying to fly? There doesn't seem to be a way to disable the input from one of the tx's

gohsthb · Post by **gohsthb** » Wed Jun 06, 2012 6:52 pm

You must have to set one of the upper channels to a switch. Then depending on that switch is which receiver's controls are put through. The main problem I see with it is the wiring nightmare that it must take to get it all connected!
-Gohst

Post by **Kilrah** » Wed Jun 06, 2012 6:58 pm

I have one of those, but never ended using it yet. Yep, just imagine 2 receivers, that module and 15 patch cables - it's a whole mess indeed

Yep there is one input channel dedicated to switching between the 2 RXs.

Post by **Crucial** » Wed Jun 06, 2012 7:07 pm

I see in the reviews that there is a switch that can be setup to give or take control

Post by **ShowMaster** » Wed Jun 06, 2012 7:16 pm

Kilrah wrote:I have one of those, but never ended using it yet. Yep, just imagine 2 receivers, that module and 15 patch cables - it's a whole mess indeed

Yep there is one input channel dedicated to switching between the 2 RXs.

Wow, I never knew about this!
Get yours in the air! We need some good intel on how it works. For our club trainers it may be a good way to go. No cables to deal with or PPM level issues.
BTW,
several years ago I bought a servo pin crimper, a good ratchet type, at a hobby show for $30. It's worth every penny! I have bulk servo wire all brands and M/F servo connectors all brands and make my own custom cables. Works for JST also and was perfect for the er9x and ersky9x mods. All my cables in my TX unplug for service. If anyone has a god lower cost high end replacement crimper please list it. I'm always making cables at the fiels for members but maybe they could own their own ha ha.
SM

Post by **Crucial** » Wed Jun 06, 2012 7:37 pm

Can you post a pic of yours? I'm curious to see if it's similar to mine?

kaos · Post by **kaos** » Wed Jun 06, 2012 7:49 pm

here is mine: (yes, you can only use 7ch, one is dedicated to the switch)
I know a guy already used this and worked fine with his Futaba and T9X. I have not used it yet, because I don't have a master or slave flyer to fly with. all solo so far.

PS: just replaced with a better pic

Malcurin · Post by **Malcurin** » Wed Jun 06, 2012 7:57 pm

Hobbyking also sell these
http://www.hobbyking.com/hobbyking/stor ... duct=20002

Post by **Crucial** » Thu Jun 07, 2012 1:53 am

I was asking show for a pic of his crimper but thanks for the pics of your trainer adapter.

Post by **ShowMaster** » Thu Jun 07, 2012 5:28 am

Crucial wrote:I was asking show for a pic of his crimper but thanks for the pics of your trainer adapter.

My crimper looks like this one. I payed $30-35 at a hobby show several years ago and but pins and shells at my local hobby shop $5-6 for a set of 10 m/fm. Less when I'm at a show.
SM

http://www.hansenhobbies.com/products/c ... /crimp_dx/

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