Scorpion XXL

[woody]

Re: Scorpion XXL

You could consider a BEC ...I've one of these ...OTT on the voltage but it gives the possibility of going mad should you ever wish to.
http://cgi.ebay.co.uk/UBEC-5A-8-40v-SBE ... 564298d0ea

[Anttazz]

Re: Scorpion XXL

Look like a good shout Woody, it talks about being for Li-Po's, does that matter that i'm using NiMH? I shouldn't think so, but thought I should ask.

[woody]

Re: Scorpion XXL

volts is volts ...Use it on any battery type combo in the stipulated range

The BEC is the part that drops the battery pack voltage (7.4v, 11.1v, or whatever) down to 5v or 6v for use by the receiver and servos. It's called a battery eliminator circuit because it eliminates the requirement for you to use a separate 4-cell NiCd or NiMh receiver battery to power them.

The BEC is usually incorporated into the ESC, so that simply plugging the ESC into the receiver is all you need to supply power to it. But often the built-in BECs are insufficient to deal with all the servos you have, or the high voltage of a 4S and upwards LiPo pack, so you can get a stand-alone BEC to do the job.

Stand-alone BECs are usually the switching kind, so they can deal with higher voltage and current than the linear kind which are usually built into the ESCs. SBEC, UBEC, and other terms have become generic terms for, usually, switching BECs. But it's always wise to check the BEC's specs, irrespective of what the manufacturer calls it, to make sure it is switching if you want high-power and/or high-voltage use.

[blazerbotics]

Re: Scorpion XXL

Have you checked the calibration? We use the XLs on our P2D and if the trims get knocked, they 'over travel' and it cuts out when you get to the end of the travel on the stick.

[Anttazz]

Re: Scorpion XXL

Sorry Alan I didn't see your post there, I will check that tomorrow when I get the chance.

I got hold of that SBEC today and still getting the same sort of problems, the motors begin to turnoff and off quickly, but I suppose that is just a case of decreasing the amount I move the stick or the acceleration on the transmitter (however that might happen) and that will fix that if it is unavoidable for the moment, the more worrying thing is the failsafe playing up, its still driving the front 2 wheels forward when I switch the transmitter off and I have tried binding the transmitter again with no joy. Is this something the XXL was also known to cause?

[jonny]

Re: Scorpion XXL

do you have a vtail mixer in there or a gyro?

[razerdave]

Re: Scorpion XXL

Mixing is on the speed controller when you add the pin jumper in. It may be an idea to calibrate the XXL, as it was stated somewhere else recently, the sticks could be going beyond their pre-set range, you need to calibrate it so it shouldn't keep shutting off like that.

[Anttazz]

Re: Scorpion XXL

I don't have either a v-tail mixer on or a gyro, i'm pretty certain no mixing is on on the handset either because I was running an external v-tail at the championships but have now sent it back to Jamie.

All the jumpers are off right now, I will try calibrating it again and see if that fixes the problems, I am hoping it will do. Right now the control is forward and back on the left stick and left and right on the right stick but only the front wheels are moving for left and right, but I have been kind of forgetting about that at the moment to try to get the other stuff sorted first.

[Anttazz]

Re: Scorpion XXL

Partial success to report. I have reset the tx so there is no mixing or anything strange going on there, binded the tx and rx again with the failsafe set properly and also re calibrated the XXL.

The failsafe is now working properly so at least I will pass tech check but still having a problem with the small jumps forward when I accelerate beyond about 60% of the travel on the stick. Also a problem which has probably existed the whole time that I haven't noticed is that only the front wheels seem to steer, the rear wheels do nothing when turning.

That is quite a confusing way to put it so will say it a different way.

Left stick: Forward and back
Right stick: Left and right, front wheels only

Any idea how I might fix that?

[woody]

Re: Scorpion XXL

You've got some weird wiring...and or some mixing happening in the tx.

Just to check your setup ... ONE XXL nothing else no additional weirdness like another speed controller for one pair of wheels?

Then..XXL.
BOTH RH Motor wires should be joined together...and connected to the XXL
BOTH LH Motor wires should be joined together...and connected to the XXL

Making sure that both paired motors rotate the correct way.

[attachment=0:245gc9bh]2M.JPG[/attachment:245gc9bh]

[Anttazz]

Re: Scorpion XXL

Haha thats correct Woody, only the one speed controller this time, none of that one Scorpion two Electronize nonsense anymore.

The way you have drawn it is the way I believe I have done it, or at least the way I meant to do it anyway, but I am beginning to think electronics is not my strong point...

I think they do rotate the same way, because forward and back work fine, its just the turning that makes only the front wheels rotate.

I reset the tx to try to eliminate any sort of mixing craziness after all this was happening but that doesn't seem to have fixed it. I will try resetting it again, that seems like the most logical solution, but I am totally stumped otherwise.

[woody]

Re: Scorpion XXL

I think they do rotate the same way, because forward and back work fine, its just the turning that makes only the front wheels rotate.

IMO It's impossible for this to happen IF wired as I've shown...and NO mixing anywhere.

Start your wiring from scratch....in fact lets start everything from scratch!

ONE SIDE AT A TIME.

[woody]

Re: Scorpion XXL

Make sure ALL mixing is OFF on the TX and XXL

pick an unused and NEVER used model number if you have that option.

Connect drive side MOTOR pairs to the XXL as shown.

TX using single RH. stick control

Connect ELE on the RX ( up - down ) lead to the XXL.

Push stick forwards ..both motors ON ONE SIDE should rotate in the same direction.
Push stick backwards ..both these motors should now reverse and rotate in the same direction.

DONE for that side.

You might find it easier to disconnect the ELE lead before trying the next step.

connect the AIL RX lead to the XXL

Repeat stick movements with the RH STICK. ( left - right )
Push stick left ..both motors ON THE OTHER SIDE should rotate in the same direction.
Push stick right ..both these motors should now reverse and rotate in the same direction.


When that is sorted we can look at wether the motors are rotating correctly to give the bot forwards and backwards... just a simple servo reverse selection in the TX menu ... ..THEN we can look at mixing.

[Anttazz]

Re: Scorpion XXL

Thanks Woody, I'll try all that out tomorrow and post some results, I appreciate the time you're taking to help.

I have tried several channels and there doesn't seem to be any difference, also I have tried turning off all mixing and the result is the same. I will try it with the Planet 5 set tomorrow too, just to rule out the possible mixing problem. I'm surprised with myself that I haven't done that earlier actually, seeing as the failsafe decided to mess itself up for no reason, who knows what else might be happening.

[Anttazz]

Re: Scorpion XXL

I took everything apart as you suggested and stuck it all back together again and after a few tweaks it works again! .

Just to sort out the mixing then its ready just in time for RL Edinburgh.

Thanks again Woody.