How safe are Arduino timers for self-bondage?
I believe that the standard setup is battery powered and uses an electromagnet for the release.
Is there anything else that should be done to improve the safety of the timer?
Shannon SteelSlave wrote:A thermal fail safe switch and also break power if it receives no light. This can protect the user from being stuck in case of fire or power failures that create freezing or no lights conditions. A fire or power failure should be a "game over" situation.
Maybe a covered release numbered code that can be emailed to a willing person, that can be offered in an emergency, or if they are willing to beg for it and satisfy a certain condition. Otherwise, see you in 4 hours.
We should get these into the hands of members to test them.
Shannon SteelSlave wrote:I was thinking about a number code that can over ride the lock command. I guess I didn't fully think that through, as it is the burden of combination code based bondage users to set the code, somehow not see it, and make it only accessible under certain conditions.
I would prefer to keep this thing from relying on internet capability.
Congratulations on your 4th star. (500 posts)
Shannon SteelSlave wrote:We should get all members' input on how to predictably make this thing safer. Try to think of all devices it can work with, as we are planning to have 4 ports, 2 five volt ports, and 2 twelve volt ports. Why don't you explain what it is? (so I can understand it) It is connected by wires, or blue tooth? Is it stationary, or does one has to keep it nearby like in a fanny pack if using "mobile bondage"? Maybe quote from some of the spin off Developer Board posts.
lj wrote:I'm not an Arduino user, still a steam-driven Assembly Language coder, but in the early days of microprocessors, we always used a watchdog timer…
And finally, always use a battery to power the lock, and only use a lock that requires power to maintain, NOT to operate a release.
It is far too easy to rely on microprocessors to take care of all processes, they are NEVER 100% reliable, whether by electronics failure or coding errors, so a simple mechanical or low-level electronics release should always be used. Like slave-L, I have, in my career, come across unexpected failures when using electronics, and particularly microprocessors, despite detailed testing, and I would never rely on a microprocessor alone to control my fate!
lj wrote:… Whilst adding to the complexity (yet more to go wrong so you need to think through the failure modes) I would only use a microprocessor with an internal/external watchdog, resetting the processor to the main code loop, so there is a very good chance that unintended code bugs will be caught, rather than cause an unexpected random inescapable loop.
The output watchdog (the one controlling the release) would be "kicked" regularly from the main processor code loop, and would drop out if the "kick" failed to appear within the watchdog time period. I think the capacitive connection for the pulse/kick is essential, as an output can fail to high as well as low, but cannot fail by giving pulses. This "watchdog", as I suggested, could be a simple as a FET (easier to get longer time periods than a transistor, though not essential) biased on (holding in a relay) by the charging of a capacitor via a diode, and capacitor fed by a port on the main processor, with a resistor in parallel with FET gate/ground to give a time constant before the FET becomes unbiased and drops the current through the relay.
The external "watchdog" must be battery powered - I would use rechargeable cells, and calculate (and test!) the maximum acceptable time to remain restrained. This way, pretty much any failure of the main processor will result in an absence of pulses, so the simple "watchdog" will release the relay, and thereby release the securing key/maglock, and as long as the lock/maglock and "watchdog" are battery powered, the final lock will release as the battery discharges.
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However, an additional mechanical emergency release is essential - you may be happy with a two-hour wait if all fails except the battery discharge release, but that won't be much use if you are choking on a gag! A simple emergency release such as the "pull the cord to get the key, which also tips engine oil over the carpet" should also be included.
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