Hallo,
I am a 53 years old guy living in Germany. After a 30 year’s pause I restarted my hobby again.
But I had no success with combustion engines, so I started now with brushless motors.
Although there are very good timers I am looking for a device for switching off the motor in case of emergency.
My goal was applying a wireless switch without changes on the timer.

This is my solution:
The pushbutton on the timer starts and stops the motor. There is a connection for a remote switch, too. My remote switch is controlled wireless by this little circuit (length 3cm=1.2inch / 5gr. = 0.2 oz.).

More information :  http://www.safaridrives.co.uk/manuals/DC3-5V-1CH.doc

There are this benefits:
- More safety in flight
- Easy testing out a new model
- Simple way to teach someone flying CL


Regards,
Martin

Hi Martin,

You can also use one of the 2.4GHz R/C car systems from Hobby Kings. They sell for around $20.00 for the Tx and Rx. I know that some have used this in simple CL trainers with great success. That sort of price is unbelievable and the throttle feature is very nice for training as well. You also don't need the timer.

Keith R

Hi Martin,

Good points........especially if lions rush into the circle! That could apply to us out here in Darkest Africa!

Are you planning to cut the battery power via that relay on the Rx board?
Keith R

O.K. thanks for the diagram. I see how the system works now. My system with the slide switch works by grounding the input for ON, so if it opens any time, it will shut down and end the program. If you close the switch again it stays in that shut-down mode. My Compact timer with the small pushbutton on the connector works the other way around. Once the system is running any pulse to ground will shut it down. Some years ago a friend of mine used my system with a few changes with a 2.4 Ghz Hobby King radio to do what you're doing, and it works very well. I like the idea of being able to shut it all down when necessary. Nice job!

Keith R

Is this gadget worth the risk?  To be worth the risk,

probability of it working when you want it to * average damage prevented > probability of it shutting off the motor when you don't want it to * average damage done

It looks like it would be a good idea for flying an ARF in a schoolyard.  It's maybe not so good for an airplane that took a lot of time to build flying in a paved, fenced-off area.

It would be especially useful for new airplanes, I think. 

I meant that new models are more likely to have problems for which a means to turn off the motor would be beneficial.  As a model's reliability increases, that benefit decreases. 

Please DO NOT DO IT THAT WAY!!!

That switch has electromagnetic relay, means mechanical contact which can easily cause reset of timer during its work, and thus risk of unexpected start after landing, what can be hardly called "safety switch".

If you really want in-flight remote cut, do it when apropriate, for examle cut the ESC power on its switch.

However proper solution will be to have zero power signal source and switch between timer signal or zero power signal. Even complete cut of SIGNAL line from timer will be more safe then cutting power to timer.

Weakest point in the system is human, give him more functions he will do more mistakes. It is much better to count that the model is armed weapon. So if you have baby which can call dadyyy while you fly, then find someone who can take care of him while you fly, if you see lions around, do not fly at all, they will chatch you and if you think you can have heart attack during flight, do not count you will have enough time to search remote controll in pocket and probably also saving model will be last thing which you have to solve in such case, simply crash it, if you land, your helper will need to solve the model first and only then to help you.

However everything is solvable, simplest way is, if the receiver cuts also his own power suppy, so it cannot activate himsel alone. But I do not thinks it is good idea to design such things without deep knowledge what and how works there.   

And may be I will add one hint for trimming. Most of us know it, but may be it will help someone - new model which needs trimming, can fly also 30 seconds if you set the timer so, so it really not need to kill it manually for first flights :- ))