Hi Tank Gurus:

Given my somewhat limited electronics skill set, and before I ruin some a perfectly good transmitter, I've come here again for advice from those with more knowledge and experience.

Background: I have a Trumpeter Tiger purchased 12/2014. It has the 2.4 Ghz transmitter/receiver. It features proportional speed forward/back (Left Stick) with Trim knob for minor adjustments to achieve straight travel. Turn (Right Stick) for turns. It also has turret rotation and gun elevation canon and machine gun fire. It works pretty well but the controls are very sensitive - a little goes a long way. The turns are very abrupt and make slow maneuvering problematic. I'm looking for an inexpensive alternative to purchasing a hobby radio and aftermarket board or changing over to Heng Long electronics. (Given my existing budget, that aint gonna happen any time soon!)

The sticks (as I'm sure is true of all transmitters) control miniature potentiometers (pots) and the trim pot is (I assume) piggy backed electronically to the turn pot, kind of like the old "Main Tuning" and "Band Spread" controls on the short wave radios of days gone by.

Given that the trim pot can make very small changes in the tanks direction, it follows that the tanks' electronics are capable of way less sensitive changes in direction than those sent via the transmitters existing stick setup.

I'm hoping that by adding a fixed resistor of the correct value (or possibly a miniature pot to make the effect tunable) in parallel with the pots that the inputs from the transmitter can be desensitized enough to make control more manageable. Hopefully they could be connected via a switch so they could be selected/deselected as desired to retain the original configuration. I understand that such a change may limit the range of motion but hope that a happy medium can be achieved, i.e. a reasonably tight turn instead of Super Spin (it is supposed to be a WWII Tank after all) and controllable speed that works in my confined space.

Whew, I've had too much coffee today. I've got to switch to decaf.

Can any of you Tank/RC Gurus wade in with your thoughts/ideas. Sadly, I only know enough to be dangerous.

As always, any input would be appreciated.

Old Fatman

What you want to do sounds like what most programmble Txs have, dual rates. You can set sensitivity that is switchable for different situations.

In terms of doing it yourself, it may be worth a try, but by the time you get done, you may not have saved anything over jusy buying a hobby Tx and being done with it.

Yeah not going to happen with a stock Tx.

Luckily there are 6+ channel hobby grade receivers and transmitter packages that are less than $30. It might be worth it to save yourself a large headache and try that. You should also try talking to YHR about using a BARC4 or a DBC system too, they are pretty cheap and do a lot. HL receivers can be found for CHEAP and the hobby recievers to attach to the RX18 are cheap as well. You would be surprised how little it takes to get going Give YHR a PM and let him know what you are looking for.

Hi ausf:

Thanks for the reply. Good advice.

I was hoping in to get by with a couple of resistors and a miniature switch or two. It's good to know that if I decide to try it out there are options available to keep the Tiger from
becoming a shelf queen when the transmitter goes up in smoke.

Wouldn't be the first project to go that route, but nothing ventured, nothing gained and lessons learned.

Cheers,
Old Fatman

Hi Imex-Erik:

Thanks for your reply.

When the coffers are empty, I entertain myself by thinking up alternate ways of getting the job done.

RC Universe is a great forum with very helpful members. Knowing that if I screw-up, help is at hand is a great relief.

Cheers,
Old Fatman

A Hobby king T6A radio is $30. It is computer programmable to allow end point adjusts, rate change, and channel mixing. For about another $100 you can buy add on electronics to convert your Trumpeter gear over to something else.

So it doesn't have to cost you a lot.

However I like to mess around with this stuff to, so I share your interest in making something better then it was delivered.

Potentiometers are variable resistors. When used with a stick they produce an end point value. This value is then observed by the electronics and the appropriate action is carried out Any joystick position can be copied by using the correct resistance in line with a button.

At the end of the day if you screw something up, it is not that big of an expense to make it right again. Nothing ventured nothing gained.

Hi YHR:

Thanks for the reply.

Sadly my tinkering has seen a lot of perfectly good stuff reduced to junk. That's why I seek the advice of those in the know.

What got me interested in what is currently just a mental exercise, is that it occurred to me, that if the on-board (tank) electronics were capable of the desired action (as evidenced by the effect of the transmitters trim pot on the direction of travel) then it wasn't the tanks electronics that needed modifying, but the transmitters.

It appears to me that the tank only does what the transmitter signals it to do (within its design parameters). As it is already capable of very slight changes in direction as well as very rapid changes, some middle range compromise should be attainable. The pots on this transmitter are very small, probably proprietary, and not easily replaced. This led me to consider adding a fixed resistor wired in parallel (Ohms Law) to modify the effect of the existing pot to signal less (or more if desired) direction change for the same stick travel. From there, why not use a pot instead of the fixed resistor so the effect could be fine tuned to the desired sensitivity. Ad a switch to disconnect the parallel resistance and you have an easily selectable dual range setup.

I only know enough to be dangerous, that's why I put ideas out here to see if those with more knowledge and experience think the reasoning is sound and it might be possible. I also was wondering if anyone had already tried this and if so, how did it turn out. I've really need that decaff.

Cheers,
Old Fatman