Transmitter conversion.

[Barry]

How would you go about converting one of the stick controlled channels on a 4 ch radio to work with a momentary on off switch?

[Eddy Matthews]

Probably the easiest way is to mount a cam on top of a servo so that at full throw of the stick it operates the switch....

The cam can be made from a disk of plywood or similar material...

Other than that, just use a normal servo arm so that it presses the switch at full throw - This needs more careful setting up than the cam so the servo doesn't bind.

[Barry]

Thanks Eddy for the reply. I haven't described what I want to do very well, but I'm hoping to disconnect the stick on the transmitter and convert it to a switch on the transmitter. It's a bit of a long story but my son only has the use of one hand. He can control the rudder / speed control on one two axis stick. We want to put a switch near that stick, to work a pump, as he finds it to hard to use the other stick.

[Eddy Matthews]

Okay, I'm with you now Barry - You can still use the method I described... Fit a cam on top of the rudder servo and mount your switch next to it. You can then get it to either press the switch at full throw of the rudder, or if that isn't wanted, by finely adjusting the switch position, you can get it so it switches at full rudder PLUS full trim....

I hope that makes sense? It's damned hard trying to explain these things in words!!

[woody]

Barry
   Motor Control Devices  has a switch 8 that replaces one channel on your trassmitter and operates 8 functions  either latched or momentary.

        site is  =  http://www.modelcontrol.com/switch81.htm

                  hope this helps Woody

[mjt60a]

...so what I think we're after is to get both 'sticks' on the same side of the transmitter casing so it can be operated one-handed....and for the 'auxiliary' control to stay where it's put....
should be possible in theory, to fit some type of changeover switch in the casing and remove the wires from the redundant stick and wire them to the switch - with resistors in series to represent the resistance of the stick (potentiometer) in different positions.
If I wanted to do that I'd measure the resistance between the outer pair of the three terminals then see what maplin have in the way of resistors and switches.....

[mjt60a]

...for example, if the potentiometer (variable resistance which is operated by the stick) measures 100Kohms across the outer terminals, it could be replaced with a pair of 50Kohm resistors in series and a switch used to connect the 'centre' wire to the centre or to one side (or using a multi-bank switch, to either side, I suppose...) like so...

[mjt60a]

...the 'redundant' stick could be left in place and the wires reconnected to the switch/resistors - which could be placed wherever is convenient (and where there's nothing else inside the case!)
***NOW I think about it...., in practice, the stick probably doesn't really move the centre connection all the way to the ends like in the drawings so you'd have to measure the resistance between the centre terminal and the ends at full throw....so you'd need something more like this -

[Barry]

Thank you one and all for your help, mission accomplished.   The red button now works what was channel one.