Building a 6ch steering wheel Tx....

[edwalsh18]

i have been reading about this Tx/Rx spektrum dx6i i am thinking it might work for me and i would like to buy it. i want to know if it can be used in a car(well truck) but with some features to suit me personally...

i have a 4WD, 4WS (2 tower pro MG995 servos), 2 speed tranny(Great Planes ElectriFly ES50 Nano Servo), now i would like to have the options of:
1. turning off rear servo and steer with just front
2. turning off front servo and steer w/ rear only
3. both on in same direction (crabwalk)
4. both on rear in reverse (normal 4WS)
5. all controlled by 1 steering stick or wheel
6. a channel for shifting a 2 speed tranny (any 2pole switch should work)

i am new to this hobby so i dont know much of how mixing works but the way i imagine it the 2 steering servos would be controlled by the steering stick or wheel(this is probably where mixing comes in?) and each with a 3 pole switch 1 position for ON(normal), ON(reversed), and OFF. now i dont know if that sounds crazy, as i dont know much but let me know what you think, if it is possible, what will i need to accomplish what i am setting out to do?

BTW i see i could probably take a short cut and use sticks to steer but i intend to use a wheel even if i have to convert a stick Tx. but using only one wheel as 2 would be 2 much 2 handle.

[Aussie Nerd]

WOW I don't know what else to say I think a certain radio will now suddenly become 6ch!!! Thanks for sticking your neck out and trying something now one else has. Now everyone else can learn from your mistakes.

Kieren

[clockworks]

Originally Posted by edwalsh18

i have been reading about this Tx/Rx spektrum dx6i i am thinking it might work for me and i would like to buy it. i want to know if it can be used in a car(well truck) but with some features to suit me personally...

i have a 4WD, 4WS (2 tower pro MG995 servos), 2 speed tranny(Great Planes ElectriFly ES50 Nano Servo), now i would like to have the options of:
1. turning off rear servo and steer with just front
2. turning off front servo and steer w/ rear only
3. both on in same direction (crabwalk)
4. both on rear in reverse (normal 4WS)
5. all controlled by 1 steering stick or wheel
6. a channel for shifting a 2 speed tranny (any 2pole switch should work)

i am new to this hobby so i dont know much of how mixing works but the way i imagine it the 2 steering servos would be controlled by the steering stick or wheel(this is probably where mixing comes in?) and each with a 3 pole switch 1 position for ON(normal), ON(reversed), and OFF. now i dont know if that sounds crazy, as i dont know much but let me know what you think, if it is possible, what will i need to accomplish what i am setting out to do?

BTW i see i could probably take a short cut and use sticks to steer but i intend to use a wheel even if i have to convert a stick Tx. but using only one wheel as 2 would be 2 much 2 handle.

The DX6i will do everything you listed easily, except item 2.

Mixing works by using the output from one channel to control another channel. In the case of 4ws, you'd mix channel 1 (front servo) with channel 4 (rear servo). You'd use 2 mixes - one would make the servos operate in the same direction, the second would make them operate in the opposite direction.

The mixes are controlled by switches, so, with both switches off, you'd get front only, one switch would give you crab, the other would give you normal 4ws. If both switches were on, they'd conflict, so the Tx ignores them both and you get front only.

On my Tx, I combined the 2 mix switches onto a single 3-position switch - simple wiring mod, and it means I only have to remember where 1 switch is!

The reason why item 2 won't work just with mixing (rear-steer only, using a single steering control) is that you are mixing channel outputs (the amount the front servo moves) to the rear steering, not channel inputs (where the control is positioned).

There is a way around this - use a 6-pole 2-position rotary switch to swap the control pot (stick or wheel) between the 2 channels (1 and 4). You'd need 6 poles (sets of contacts) because the channel that wasn't connected to the pot would need some fixed resistors to keep it centred.
I wish I'd thought of this mod when I was building my Tx - I may go back and try it!

Shifting the tranny is easy, using channel 5 or 6. These are each controlled with a 2-position switch.

So yes, a Tx based on the Spektrum DX6i can be modified to do everything you want.
Be sure to post when you start the build.

[clockworks]

Originally Posted by Aussie Nerd

WOW I don't know what else to say I think a certain radio will now suddenly become 6ch!!! Thanks for sticking your neck out and trying something now one else has. Now everyone else can learn from your mistakes.

Kieren

It's certainly been a learning experience. What Tx are you going to use as a base?

[FritoBandito]

Wow. Brilliant work! Makes my silly TQ3 mod seem amateur.

[clockworks]

Originally Posted by FritoBandito

Wow. Brilliant work! Makes my silly TQ3 mod seem amateur.

Don't do yourself down - your "sticky" was one the things that got me started on this project

[toy4crawlin]

I heard the DX6 has same programing as the 6i, but I dont see how that is since there is another toggle for mixing.

have any other detailed pics of the little mods inside ?

[edwalsh18]

Originally Posted by clockworks

So yes, a Tx based on the Spektrum DX6i can be modified to do everything you want.

how about a dx6?

[edwalsh18]

also, will i be able to convert the DX6 or DX6I(if DX6 doesn't work), like you did with your radios, into my TQ3? or at least take the wheel and trigger off the TQ3 and add it somehow to the DX6 or DX6I? BTW let me know if it is at all possible to do what i had previously described with the DX6. thanks!

hey and thanks alot for the info.

[clockworks]

Originally Posted by toy4crawlin

I heard the DX6 has same programing as the 6i, but I dont see how that is since there is another toggle for mixing.

have any other detailed pics of the little mods inside ?

AFAIK, the extra switch on the DX6i is for rudder dual rates - I think that everything else is functionally the same, except for the 6i being DSM2 and the DX6 being DSM, maybe the batteries are different as well?

For some reason, I didn't take any more pics inside - you wouldn't see much, just a load of wires! Next time I take it apart, maybe to do a mod to allow the wheel to do RWS only, I'll take some more pics.

Any questions on how the individual mods were wired up, feel free to ask.

[clockworks]

Originally Posted by edwalsh18

also, will i be able to convert the DX6 or DX6I(if DX6 doesn't work), like you did with your radios, into my TQ3? or at least take the wheel and trigger off the TQ3 and add it somehow to the DX6 or DX6I? BTW let me know if it is at all possible to do what i had previously described with the DX6. thanks!

hey and thanks alot for the info.

The DX6 will work, but the main PCB is a fair bit bigger, so you might struggle to make things fit - see toy4crawlin's thread about doing a DX6 conversion, the post that got me started on this project.

Yes, you could do the conversion using a TQ3 as the base. The only parts that are really needed from the base Tx are the case and the wheel and throttle assemblies. All wheel Txs basically work the same way with 2 pots. You might need to use slightly different resistors than I did, depending on the value of the pots used in the TQ3. Not a problem, as it's easy to work out the correct values to use.

In some ways, the electical part of the conversion would be easier with a TQ3, as it has more throttle travel than the KO that I used.
The difficult bit would be making all the parts fit. The KO has a very square case, so the bits fit easily

If you've not got a Spektrum to cannibalise, there was a thread here a couple of weeks ago by a Spanish member who converted a basic PC-configureable 2.4GHz Tx - might be a cheaper option, as long as the Tx has 2 programmable mixes.

[Aussie Nerd]

Hi clockworks

I have this really old hitec I got with a freebie car a long time ago. It is HUGE. the case should easily fit a dx6i. I don't think the receiver works properly anyway so it's no great loss. It actually looks quite similar to the mars just a bit more room in the case area. How well is the styrene holding up for you? Would it be strong enough to make the majority of a case out of it? Does it take ages to learn how to get it as nice as you can? I think you poms have us aussies beat We can't beat you at cricket and now this (Please take no offense, Its a compliment)

Kieren

[Aussie Nerd]

I jsut thought this up, but is it possible to stick a few leds in the case and light up the screen? This would be wonderfully helpful as the screen is mighty hard to see. The only problem is it might 'wash out' the writing even more.

Kieren

[toy4crawlin]

Originally Posted by clockworks

AFAIK, the extra switch on the DX6i is for rudder dual rates - I think that everything else is functionally the same, except for the 6i being DSM2 and the DX6 being DSM, maybe the batteries are different as well?

For some reason, I didn't take any more pics inside - you wouldn't see much, just a load of wires! Next time I take it apart, maybe to do a mod to allow the wheel to do RWS only, I'll take some more pics.

Any questions on how the individual mods were wired up, feel free to ask.

Whats " AFAIK" ?

I have heard that DSM2 takes less power to run such a 4 AA batteries not a 9.6v also it lasts a lot longer

I'd like to know how you got a the rear steer pot to give you a notch to show where center position is and How the Blue mini pots where wired in ?
Also How would I know where to add a resistor ?

how come you could not use a different dial for the rotary encoder ?

Thanks

Clockworks really built this Fast, made it look easy

[edwalsh18]

Originally Posted by clockworks

Next time I take it apart, maybe to do a mod to allow the wheel to do RWS only, I'll take some more pics.

wow, i wonder if anyone else has thought about it and mentioned it? I can't believe i would be the first! i just have too many ideas! but that would be cool to see you do it.

Originally Posted by clockworks

If you've not got a Spektrum to cannibalise, there was a thread here a couple of weeks ago by a Spanish member who converted a basic PC-configureable 2.4GHz Tx - might be a cheaper option, as long as the Tx has 2 programmable mixes.

i read a few forums about it ALL DAY yesterday, too bad i dont know crap about mixing, and any other radio functions that my TQ3 doesn't have. but i am sure that it needs to be programmed by a laptop or computer, but if it is possible to do what i am trying to accomplish with that Tx let me know and i will go that route.

Originally Posted by clockworks

Yes, you could do the conversion using a TQ3 as the base. The only parts that are really needed from the base Tx are the case and the wheel and throttle assemblies.

another idea is i could just add those components to the DX6

[clockworks]

Originally Posted by Aussie Nerd

Hi clockworks

I have this really old hitec I got with a freebie car a long time ago. It is HUGE. the case should easily fit a dx6i. I don't think the receiver works properly anyway so it's no great loss. It actually looks quite similar to the mars just a bit more room in the case area. How well is the styrene holding up for you? Would it be strong enough to make the majority of a case out of it? Does it take ages to learn how to get it as nice as you can? I think you poms have us aussies beat We can't beat you at cricket and now this (Please take no offense, Its a compliment)

Kieren

Styrene is almost as strong as the ABS used for the original case. I bought a pack of sheets on eBay, various thicknesses between 0.5 and 3mm. It's stuck together using dichloromethane solvent, available from most hobby stores. Used carefully, the joints won't fail.
If I was to make another one, I'd spray paint the whole thing to achieve a more consistent finish.

The case work is pretty simple, just time consuming. I reckon I spent about 30 hours on the styrene work. Cut all the parts to fit snugly, use plenty of solvent to weld the parts together and leave to set over night. Use a sharp number 11 blade to trim away the excess plastic, then sand using progressively finer sheets of wet-or-dry paper for final finishing. I used 320, 600, 1200 and 2000 grit papers.
A full sheet of 320, stuck to a sheet of glass, helps with trimming square/flat surfaces.

I reckon you could make a complete case from styrene if you had the patience. For complex shapes, it's easier to laminate a few thinner sheets together, rather than using one thick sheet. I always reinforce inside all the corners with scraps of styrene - small strips or triangles.

As for the cricket, isn't it the first time we've beaten you at Lord's in over 70 years? We were playing a game that we invented, at the "home of cricket", so we really should beat you at least once a century.

[clockworks]

Originally Posted by Aussie Nerd

I jsut thought this up, but is it possible to stick a few leds in the case and light up the screen? This would be wonderfully helpful as the screen is mighty hard to see. The only problem is it might 'wash out' the writing even more.

Kieren

Have you tried altering the screen contrast?
A backlight should be possible. Cut a strip of clear acrylic to butt against the edge of the display. Sink a couple of LEDs into the acrylic, like a light tube.

[clockworks]

Originally Posted by toy4crawlin

Whats " AFAIK" ?

I have heard that DSM2 takes less power to run such a 4 AA batteries not a 9.6v also it lasts a lot longer

I'd like to know how you got a the rear steer pot to give you a notch to show where center position is and How the Blue mini pots where wired in ?
Also How would I know where to add a resistor ?

how come you could not use a different dial for the rotary encoder ?

Thanks

Clockworks really built this Fast, made it look easy

AFAIK = "as far as I know"

Yes, DSM2 uses 4 cells. Battery life seems to be at least 20 hours on 2100mAH rechargeables.

I posted a couple of pics showing the detent assembly:



It's a spring-loaded plunger that sticks through the front of the case. The rounded end of the plunger locates in a cutout in the control knob. As the knob is turned from the centre, the plunger is forced back into the case against the spring. When you rotate the knob back to the centre position, the plunger pops back out into the cutout.

The blue trimpots are just wired in series with the track of the main pot. For example, with the rear steer pot (rudder channel), I fitted 2 trimpots:
positive feed (red wire) that went to original pot goes to track of first trimpot
wiper of first trimpot goes to rear steer pot track
other end of rear steer pot track goes to wiper of second trimpot
track of second trimpot goes to black wire that went to original rudder pot

For the front steer and spare channels, I just fitted a trimpot to the positive side of the main pot.


You need resistors on all the 4 main control channels at all times, either the main control pot or some fixed resistors or trimpots. So. if you bypass or remove a main pot and replace it with a switch, you need to add resistors to simulate the pot.
Think of it like this:
The main pot is a 5K resistor, connected between the positive rail and ground. The wiper of the pot (connected to the stick or knob) moves up and down the 5K resistor. At the mid point, it's like having a 2K5 resistor between the wiper and positive, another 2K5 resistor between the wiper and ground. All this does is split the voltage on the wiper 50:50. If positive is 5v, you get 2.5v on the wiper.

At the positive end of the pot's travel, it's like having a 220R resistor between the wiper and positive, and approximately 4K8 between the wiper and ground.
Move the pot to the ground end, and the resistances are reversed - 220R to ground, 4K8 to positive.

This is what you have to simulate with fixed resistors when you use a switch - 50:50 to positive and ground for mid point, low resistance to positive OR ground at each end.

The actual values of the resistors aren't critical, it's the ratio between positive and ground that's important. Fixed resistors come in "standard" sizes - 220R and 2K2 are good sizes to use.
Not sure if you are used to the notation used, so 220R is 220 ohm, 2K2 is 2200 ohm.


When you ask about using a different dial for the rotary encoder, do you mean the one used for the scroll wheel from the DX6i, or the one used for the thumbwheel on the Mars?

[clockworks]

Originally Posted by edwalsh18

wow, i wonder if anyone else has thought about it and mentioned it? I can't believe i would be the first! i just have too many ideas! but that would be cool to see you do it.



i read a few forums about it ALL DAY yesterday, too bad i dont know crap about mixing, and any other radio functions that my TQ3 doesn't have. but i am sure that it needs to be programmed by a laptop or computer, but if it is possible to do what i am trying to accomplish with that Tx let me know and i will go that route.



another idea is i could just add those components to the DX6

I've not seen anyone else mention this idea - looks like you're the first

Yes, that cheap Tx doesn't have a display, so you need to program it from a PC. Try and download the software, see what options it has. If you can't figure it out, post a link to the software and I'll have a look.
Mixing is pretty simple - you use one channel to control another at the same time (aileron controls rudder in this case).

Yes, you could just join the 2 Txs together with some cables.

[mrklaw]

this is pretty damn amazing. I'm actually quite surprised nobody has come out with a 6ch pistol radio. Not just for crawling, but those scale truck guys have a ton of things to control, and they've been around for longer than crawling - do they just use sticks?

maybe with crawling getting so much traction recently (pun intended) we'll see one of the manufacturers bring out a crawler friendly pistol.

Never mind mixing this and that - basically all we want is a nice simple 4ws setup, and a bunch of 2/3-position switches for winches, lights, digs etc