As I mentioned in my last post, I'm waiting for a 2.4GHz orangeRx transmitter/ receiver to arrive at the moment, but because I wanted to play with it now i got out an old 40MHz 2 channel RC set which came with two servos which i found in the attic. Stripped out the servos for their controller boards, replaced the potentiometers with fixed resistors, and wired in the new motors. This seems to bee a fairly well known way of doing a quick speed controller.
However, each channel controls each motor with no mixing, which on a cheap transmitter means the throttle stick does one motor and the left/right stick does the other, which is hardly ideal..
So, in a moment of boredom today, i took apart my transmitter and had a little tinker to solve this problem.
After about a while i came up with this:
On my transmitter, the signal from the sticks was about 2.5v with +-0.5v being the change from a full stick movement. All my mod does is wire both channels into the throttle stick, and then use the left stick to apply a bias to do the steering. The resistors to the 0v are just to adjust the voltage back to 2.5v. Your transmitter might have slightly different levels, but you can tweak the resistor values to suit.
Nice and simple, but i couldn't find it anywhere on the forum so thought i'd share it.
Here's how it looked wired in:
It also solves one of the other problems with servo-based ESCs. If you haven't used one, servo ESCs are very twitchy, where you only have to move the stick a few degrees before its at full speed. However my mod can be used to reduce the over all range of the stick's signal to somewhere about +- 0.2v instead of +- 0.5v, which makes the servo ESC much more useable..
So I'm now slightly annoyed having shelled out lots of money for a 6 channel transmitter with mixing, where I could've just bought a cheap 2.4GHz transmitter and used any old ESC... But ah well, thought i'd share it for anyone who was looking to work on a budget, or re-purpose an old RC kit.
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