Throttle Cut with Extra safety

You’ve probably already had it once, walk around with your transmitter and accidentally push your throttle stick open. often it goes just fine.

Below is a trick with extra security to prevent that as much as possible.

What does the trick do:

To ensure that the engine cannot be switched on accidentally, it would be nice to be able to use a switch that ensures that Throttle stays closed at all times.

You can do this by creating a “SPECIAL FUNCTIONS” .

You need a number of details:

  • Switch that controls this function.
  • Which (servo) channel must be operated.
  • And in what position this channel should be set, in terms of value.

In this case we use a 2-position switch SF to switch this function on and off.

A nice feature in OpenTX is the ” Override ” function.
Once this function is switched on, this function literally really overrides all other functions and mixes.

For the sake of convenience, let’s choose that CH3 is the channel to which the ESC is connected.

OpenTX works as standard with a servo range from -100 to 100.

In this case, -100 is the value at which the Throttle stick would normally be closed.

So what we have to do is ensure that switch SF performs an override on CH3 in the desired position SF ↑ or SF ↓

That looks like this in the following picture:

Important note is !: See the box to the right of this line .. it is checked here, which means that this line (function) is active !.
Be careful with that on a Throttle channel. it may just be that you should have set instead of -100, 100. when activating the box. this function may immediately implement that value if this function is active! be warned!


We go one step further in this story.

The above function is already a very good start as security. but it can be a bit safer or more luxurious.

We are going to create a function where regardless of the position of the Throttle stick, the channel can override.
But now add an extra piece of code, that Throttle is only available again if the Throttle stick has been closed for a while !.

This has the advantage that if you accidentally have the Throttle stick open, and open the Throttle cut switch, the engine will not run.

To make this function, we need to create some logical conditions:

We do this in the menu “LOGICAL SWITCHES”

In the first picture below we see a function called A ~ X

In this position, condition means that the position is:

  1. Throttle stick ( A )
  2. Is different ( ~ ) then
  3. -100 ( X )

We also see SF ↑ in the same line, which stands at the position of AND.

For this rule this means:
The condition L01 is only valid if the throttle stick position is different from -100 AND SF is in the  position.

Now for line L02 what exactly does it mean:

We see here a condition called “Stcky” or Sticky.

What does Sticky do in this case:

By putting switch SF in position  , we activate the condition, it remains (sticks) in this position. Regardless of whether you switch the SF switch back to the  position.
To undo this condition, function L01 must be active.

So we are almost there, L02 gives us exactly what we want in this story.
Only this status of L02 does not yet cause an override on our Throttle channel. for this we now have to go back to the “SPECIAL FUNCTIONS” menu. See bottom plate.

The only thing we have to adjust here is that now switch SF does not activate the override function. but L02

Good luck!

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