Self-Bondage Smoke Detector

[Riddle]

So, in case of a smoke or fire emergency, obviously immediate release and appropriate response would be necessary. The question is how to ensure this happens in an expedient manner regardless of whatever sensory deprivation may be present and without requiring the use of the emergency release method.


This is the initial step to ensure that the timing system halts when the smoke alarm alarms. The left wire is power input and the right wire is the interconnect.

The next step will be connecting this to the electronic timer for the expected result. In my mind, the smoke alarm is of such importance that updating the timer firmware is not the appropriate method. Instead, I would like to completely kill the system power when the alarm is active. The smoke detector interconnect is an extra wire that is normally 0VDC to the neutral wire and goes to 9VDC during the alarm condition.

For power control circuits, an active low signal removes power and an active high signal allows power. The smoke detector has this logic inverted. So, I need a circuit that will reliably invert the logic, remove power, and not interfere with the smoke detector system. My first thought is a large TO-220 power MOSFET connected to the power supply so it shorts out the power supply and blows the fuse when active. Does anyone have any suggestions for this?

[Riddle]

This suggestion has a few assumptions that limit the applicability to some specific types of Self-Bondage. First, the use of an existing electric or electronic system timer is expected. Second, the bondage must be stationary to allow for the additional connected devices. Third, the bondage must be inescapable enough that the primary release mechanism or an alternative means are not readily accessible.

Also, the emergency release mechanism must be evaluated with the pros and cons compared to hardwiring the smoke detector into the system. Is the emergency release benign enough to not care if it is used for a false alarm? Will it be quicker to use or adequately quick to make the smoke detector connection irrelevant? Is the assurance that the bondage session will end immediately with the alarm instead of waiting for the person bound to make the decision and then actually using the emergency release desirable?

Given that everyone is unique, I am confident that each person will have their own personal evaluation and decide for themselves whether or not to implement this strategy. This is none of my concern. I am simply sharing my strategy to make it available and requesting feedback for the interface circuit.

I desire every Self-Bondage enthusiast to have the knowledge they need to be safe and have fun.

[Shannon SteelSlave]

What you are proposing should be implimented as another release mechanism, not to replace the primary or emergency release.
One might also develop a smoke detector unit to cut power from a 120 volt or mains outlet where electromagnets are employed, or even just a sort of "Key Safe" that will open or drop a key if the alarm is triggered. It would be a great release if an overzealous person were to enter their trap without making sure the oven is turned off, or if the unlikely event of a fire occurs, giving them enough time to put out the fire or escape.

[Kinbaku]

My first thought is a large TO-220 power MOSFET connected to the power supply so it shorts out the power supply and blows the fuse when active. Does anyone have any suggestions for this?

Such as a normally closed contact of a relay (system of your MOSFET). When power comes from the smoke detector, the contact opens and breaks all your bondage connections. Can possibly be combined with an AND gate so that you can decide for yourself whether to free yourself or not in the event of a false alarm.

[Shannon SteelSlave]

My first thought is a large TO-220 power MOSFET connected to the power supply so it shorts out the power supply and blows the fuse when active. Does anyone have any suggestions for this?

Such as a normally closed contact of a relay (system of your MOSFET). When power comes from the smoke detector, the contact opens and breaks all your bondage connections. Can possibly be combined with an AND gate so that you can decide for yourself whether to free yourself or not in the event of a false alarm.

I would think it should only be made as an automatic release, with no "Ignore" option. In the event of an alarm trigger, all bondage bets should be off. The user should learn then not to leave the stove on or the tea kettle boiling. All fire alarms should be taken seriously.

[Riddle]

What you are proposing should be implimented as another release mechanism, not to replace the primary or emergency release.
One might also develop a smoke detector unit to cut power from a 120 volt or mains outlet where electromagnets are employed, or even just a sort of "Key Safe" that will open or drop a key if the alarm is triggered. It would be a great release if an overzealous person were to enter their trap without making sure the oven is turned off, or if the unlikely event of a fire occurs, giving them enough time to put out the fire or escape.

Yes. This idea is intended as an independent, abrupt, and absolute end to whatever Self-Bondage activity is occurring at the time of the alarm. Definitely no need for user input such as an And gate. As for implementation, for my own system, the Arduino timer is the primary release method, the battery powering everything is the backup fail-safe timing method, and rapid release of all air pressure is the emergency release mechanism. This means that killing the battery power to everything makes good sense to me.

For some Self-Bondage setups, an alternative means of providing the key for release is completely acceptable and actually the proper way to perform an alternative release mechanism. However, this is me and my system which will have the first implementation of the smoke detector alternative release added. With my system, my hands are palm up without any access to perform any release other than the emergency release method. Even starting with complete sets of keys in both hands, the only method of release is the emergency mode. My fingers cannot move back enough to even feel the edge of the wrist restraints; the 4-pin circular locks are 1.5 inches beyond that and off to the side.

Installing a normally closed relay controlled by the smoke detector “power” is not an option. The smoke detector is only expected to raise the signal line to 9VDC with explicit and extremely limited conditions without any electrical power specifications given. To directly control a relay with the signal line is much more likely to start a new fire within the smoke detector than the intended outcome. Given the cost of the smoke detector and the reliability needed from it, I refuse to attempt pulling 1mA or 0.009 Watts of power from it. I believe that the gate pin of a power MOSFET with appropriate resistors attached will be an acceptable signal detection method. Anything above that power draw risks circuit damage and failure during an emergency situation where either of those may be extremely life threatening.

If the power source was something more substantial, I would be happy to energize a relay or two that both disconnect the load circuits and short out the power supply to trip a circuit breaker. Shorting out the power is the normal method for wiring an emergency stop switch in both industrial and military applications. However, the small lithium ion batteries involved are fragile and some of them may have issues with getting shorted through a 1A fuse. Their current output may not be enough to blow the fuse. The data sheets for 1A thermal circuit breakers show much worse results than the fuses: they may take hours to heat up enough to trip depending on the short circuit current of the battery. After reading the data sheets for the fuses and circuit breakers, I have decided that shorting out the power in this instance will not be acceptable.

While I am rather interested in adding a small fuse into my control system, the circuit between the smoke detector signal output and my control system will need to rely on something else. Of course, this has been on my mind since before my original post here. My preference leans toward a solid state design as opposed to an electro-mechanical design.

Late into last night, I was researching digital inverter circuits and the NMOS inverter circuit on Wikipedia has the best potential. To implement this to control power to my system, a pair of MOSFETs and 3 resistors are all that is necessary to control the system power. The first MOSFET gate is pulled low by a 10k resistor through a 1k resistor. The smoke detector signal connects to the 10k/1k resistor junction. This MOSFET source pin goes to the power supply through another 10k resistor. The second MOSFET gate goes to this 10kR/Source junction which will be high until the smoke detector switches on the first MOSFET. So, this second MOSFET will allow power to the control circuit until the alarm signal goes active.

The resistor values are the usual values for controlling a MOSFET with a microcontroller pin such as an Arduino. At this time, those values also seem like good choices because I bought 1k of each for my failed timer circuit board kit business venture. Of course, I intend to do some circuit tests and calculations to confirm the values are correct. If more resistance is required, some series of 10k and 1k will be used instead of considering the purchase price and shipping costs of resistors with the required values.

Please wish us all good luck!

[Kinbaku]

Please wish us all good luck!

On the right track.
Good luck!

[Riddle]

… One might also develop a smoke detector unit to cut power from a 120 volt or mains outlet where electromagnets are employed…

I forgot to comment on this part in my last TL:DR text wall: the use of 120V or mains outlet power with electromagnets for Self-Bondage applications is strongly discouraged because the power source is expected to continue much longer than a person may survive in bondage. In the event of a timing issue, the electromagnets staying powered is a fail-death design. The alternative battery powered system has a definitive fail-safe design with the maximum time possible determined by the battery size. Safer is better.

[KinkInSpace]

Maybe consider going the smart-home route.

You can buy off-the-shelf smart home sensors that can connect to an eco system. A smoke alarm sensor can be bought that, once activated can trigger a scene.

You can connect this to other stuff, such as cutting the power to a relay, turn on the light, make an alarm go off so people in the area will draw their attention to your house, unlock doors and countless other things are possible.

One caveat though, if you go for a cloud-based smart home solution, such as tuya, if their servers have issues, your smoke alarm won't work either. Also, if your wifi has issues, it may also not work.

In essence, if there's a powerfailure, it may break your solution, but if you engineer something with powerfailure auto open solution, you should be fine. Also, if you can, make a local server and connect to that. It will ensure your smart home solution will always run even if you have no internet, as long as you still have wifi.

[Riddle]

Currently, I have 3 different brands of smart home automation, WiFi, and full battery backup for the entire power panel in my tool shed.

Maybe consider going the smart-home route.
…

Will not consider this approach for my Self-Bondage smoke alarm alternative release method.

The half of my shed lights with WiFi control are a minor inconvenience when the internet is down. The other day, the WiFi was down and I was concerned about my outdoor lighting not getting the “on” command while I was away; the solution was manually switching it on before I left. Several weeks ago, the interior WiFi lights stopped working and I had to contact the manufacturer for help. They instructed me to remove all devices from my account and reload them into the cloud which worked. For something I consider safety-critical, so many failure points and potential issues are unacceptable.

You do have a good point about the level of dedication and permanent modification involved with this hardwired solution. The likelihood of someone other than me actually completing this modification is extremely low. Still, I am going to follow through on this and make the information available to others.

An alternative solution that will respond appropriately to smoke, fire, and other alarms would be good for those not wanting to hardwire their Self-Bondage system to their smoke detectors. I will definitely try to figure out some reliable ways to accomplish the same goal with other implementations. Perhaps microphone, Bluetooth, and WiFi will offer some good options.

[nocrad]

Installing a normally closed relay controlled by the smoke detector “power” is not an option. The smoke detector is only expected to raise the signal line to 9VDC with explicit and extremely limited conditions without any electrical power specifications given. To directly control a relay with the signal line is much more likely to start a new fire within the smoke detector than the intended outcome. Given the cost of the smoke detector and the reliability needed from it, I refuse to attempt pulling 1mA or 0.009 Watts of power from it. I believe that the gate pin of a power MOSFET with appropriate resistors attached will be an acceptable signal detection method. Anything above that power draw risks circuit damage and failure during an emergency situation where either of those may be extremely life threatening.

I have no idea what kind of load you can put on the output of the smoke detector, but if you want to keep it safe you probably need to do some research into what the limit is. You mention not wanting to pull even 1mA. But later on in your post you mention a 1kΩ gate resistor for a mosfet. 9V and 1 kΩ means an initial current of 9/1000 = 9 mA will flow to charge the gate of your mosfet. Sure the duration is on the order of μs, but you will be exceeding your own limit.

If the power source was something more substantial, I would be happy to energize a relay or two that both disconnect the load circuits and short out the power supply to trip a circuit breaker. Shorting out the power is the normal method for wiring an emergency stop switch in both industrial and military applications. However, the small lithium ion batteries involved are fragile and some of them may have issues with getting shorted through a 1A fuse. Their current output may not be enough to blow the fuse. The data sheets for 1A thermal circuit breakers show much worse results than the fuses: they may take hours to heat up enough to trip depending on the short circuit current of the battery. After reading the data sheets for the fuses and circuit breakers, I have decided that shorting out the power in this instance will not be acceptable.

My knowledge of emergency stop switches is quite limited, but I would be very surprised shorting power is common. That just sounds like asking for problems. Especially in industrial applications. The few I worked with controlled a contactor.

While I am rather interested in adding a small fuse into my control system

You should, it might prevent the smoke alarm being needed in the future.

My preference leans toward a solid state design as opposed to an electro-mechanical design

Solid state or electro-mechanical, if I were to design a circuit I would prefer to keep the smoke alarm and my self bondage system galvanically separate. So either opto-coupler or relay.

You may also want to look into relay modules specifically designed to hook up to smoke alarm interconnects. They are meant to control things like emergency lights or an additional siren.

[Shannon SteelSlave]

Good to meet you, Nocrad

[Riddle]

Welcome to the forum nocrad. Happy to see your first post here and appreciate your input.

Installing a normally closed relay controlled by the smoke detector “power” is not an option… I refuse to attempt pulling 1mA or 0.009 Watts of power from it…

I have no idea what kind of load you can put on the output of the smoke detector, but if you want to keep it safe you probably need to do some research into what the limit is. You mention not wanting to pull even 1mA. But later on in your post you mention a 1kΩ gate resistor for a mosfet. 9V and 1 kΩ means an initial current of 9/1000 = 9 mA will flow to charge the gate of your mosfet. Sure the duration is on the order of μs, but you will be exceeding your own limit.

Good catch on the initial charge current of the MOSFET. I completely understand your confusion between the two statements. The difference is my definition of “pulling”: to require constant current through either a resistive or inductive load. The capacitive load of the MOSFET while the signal is steady is approximately 200nA for 0V and likely similar for 9VDC. During the MOSFET capacitive voltage change, with the 1k resistor, I expect this additional capacitance added to capacitance of the wire run will be so insignificant so the smoke detector circuit will not perceive the difference.

However, adding either a resistive or inductive load on the signal line is an entirely different matter. Your suggestion to research the allowable current draw would normally be appropriate and valid. In this specific instance, my research gave an answer without a specific current allowance: only connect certified devices! Obviously, I am planning to violate that. So, this leads to me being rather cautious with my added circuit. The limitations on the interconnect are rather specific and rather limited. Only 18 devices with only 12 of them being smoke detectors is allowed. This furthers the concern. Also, my smoke detector has no relay click when pushing the test button so the signal output circuit is likely to be solid-state. So, I have a solid state circuit with unknown current limits and testing the limits is expected to be destructive testing. Even without instant and catastrophic failure during testing, the tests could significantly degrade the detector circuit and would require replacement of the detector to ensure reliability and safety. So, testing the limits is unacceptable. Instead, I will measure the characteristics of my smoke detector when it receives 9VDC and stay well below that.

If the power source was something more substantial, I would be happy to energize a relay or two that both disconnect the load circuits and short out the power supply to trip a circuit breaker. Shorting out the power is the normal method for wiring an emergency stop switch in both industrial and military applications...

My knowledge of emergency stop switches is quite limited, but I would be very surprised shorting power is common. That just sounds like asking for problems. Especially in industrial applications. The few I worked with controlled a contactor.

Oh, it has known issues when the button gets pushed. Every time I was briefed on the button, heavy emphasis on the “Emergency” was given. When I worked aircraft maintenance with multimillion dollar test stations, everyone was warned of the devastating consequences of the big red button and given multiple preferred alternative options to that button. On the backside of the button was 6 poles of heavy gauge wire intended to short a pair of 3-phase power inputs (60 Hz and 400 Hz) simultaneously and instantly. The relevant breakers were well above 100A each. The normal power-down-to-standby button initiated a slow and careful shutdown sequence that left power to a few critical parts.

In a military classroom with an emergency button, I accidentally bumped the button while putting a clock on the wall above it. All power in the classroom instantly cut out and the instructor had to make a mad scramble to shutdown the training computer server and training computers before their small UPS batteries gave out. The breaker for the room had tripped in the building electrical room and would not reset until the button was un-pushed (reset).

I have no clue what determines when an emergency button is installed or required. I only know that all of them known to me created a short to kill power. Very rarely is such a button available though. For most things, the equipment’s power switch is adequate. In military, industrial, and manufacturing settings; a red stop button where everything goes to a safe state before power removal is usually preferable. A friend told me about the stop line for a massive assembly line that ran the entire length of the line and halted everything in the warehouse room. It did a controlled shutdown, but required hours to restart everything. Each station had its own stop button as the preferred stop method.

My preference leans toward a solid state design as opposed to an electro-mechanical design

Solid state or electro-mechanical, if I were to design a circuit I would prefer to keep the smoke alarm and my self bondage system galvanically separate. So either opto-coupler or relay.

A valid consideration, but not something I feel necessary for this interconnect at this time. Giving my self-bondage control system reference to the building neutral potential (tied to earth ground) is not an issue. Taking precautions to limit the voltage potential between the neutral and signal wires at my MOSFET makes better sense, but not enough to require immediate attention.

You may also want to look into relay modules specifically designed to hook up to smoke alarm interconnects. They are meant to control things like emergency lights or an additional siren.

Funny you should mention this. It was actually my first thought. However, those require 120VAC to function, require significant additional wire connections, usually are wired to output their 120VAC supply to their output, and are significantly more expensive. Would prefer to minimize complexity and potential failure modes.

[Kinbaku]

Welcome to BoundAnna, nocrad.