Hi all, i am trying to make a kill switch(otherwise known as dead man switch) that will be placed between arduino and sabertooth.
It is required to stop the motor from running.
However, the tricky part is that sabertooth requires 2.5v to stop the motor.
0 to 2.5v = reverse
2.5v to 5v = forward
I tried using an audio jack,socket but it seems like the socket isn't well built and there are voltage leakage when i insert the audio jack.
Thanks in advance for the help!
I don't know what a 'sabre tooth' is but it does sound like the sort of thing I should have.
Is the 0 to 2.5v = reverse 2.5v to 5v = forward a control signal? or is it the actual power that drives the 'sabre tooth' I am guessing electric motor of some kind.
Si: it's a motor driver
yes it's a control signal...page 10 of the pdf states that.
Richard: thanks for pointing that out! i have a rough idea on how to implement it...just now sure if it's entirely safe!
i'm expecting the current to hit about 20A max...
Battery 24v -> 20A fuse -> 20A rating switch
thanks for the help...! won't be able to get the deans ultra plug for now, will keep that as one of the options!
also, ill be using a 20 A rocket switch for the deadman switch.
then some time later, hope to modify it such that it'll be switched on/off using a "key".
will be thinking about ways to do it in the meantime....
any suggestions? 
If you are serious about doing this the right way, you shouldn't use a rocker switch or a key switch either. It is too easy in a panic to hit the switch and turn it off and back on in rapid succession and you don't want to rely on someone reading which direction is off vs. on in a panic.
Key switches are good for preventing someone from powering up the system when you don't want it to be, but are no substitute for a panic button.
You should be looking at using a mushroom head push button switch. They generally are maintained so that you have pull out after being mashed down. This way in a panic someone can press that damn button as many times as they want and it will stay off.
As Richard says this shouldmust go to the mains feeding power to everything. You never want to rely on potentially faulting logic to cause a machine to return to a 'safe' state.
Took the advice and connected the switch to the main power source.
I'm interested in using the mushroom head push button switch method.
Not sure about exactly what to use though..
From what research I've done so far, most makers of EMO switches are seriously proud of them (expensive). I did check EBAY though, and some nice onese are available for as low as $9.00 each which really isn't that bad after seeing all the other crazy prices (some as high as $500).
Enter EMO into ebay search.
example: http://cgi.ebay.com/EMO-SWITCH-/280470926894?pt=BI_Pumps&hash=item414d5eb62e
True, EMO switches can be expensive. Some of the money goes to the certifications to prove they will work when needed. The rest goes to the lawyers to defend the company when they don't work.
So, just weigh the cost savings vs. the potential for damage if something goes wrong.
If you got a multi-million dollar piece of equipment that can maim/dismember/kill when it malfunctions I would avoid the $9 ebay specials.