Electronics Help

[1inmate]

I have built a new cell in my house, it is made out of concrete block walls with a concrete ceiling.

I plan to intsall a electric bolt lock on the door so I can lock myself inside. The lock will be "fail safe" meaning if the lock losses power, it will unlock. For an extra measure of security, I would like to get an interface from my alarm system to the lock, so if the alarm goes off for any reason (fire, smoke, intruder, etc.), the power to the lock will cut, and the lock with unlock.

I talked with the alarm company, and during an alarm, the siren produces 12 volts. The tech advised me that I need a relay so the 12volt output will kill the power to the 120 volt receptacle that the lock is is powered by (i did not tell him what the real purpose of this was for)

My thought was to have a 120 volt recep that was controlled by a timer where the power came to the timer could be interupted by the alarm going off. Therefore, if I lost power to the house, the lock would unlock, if the alarm goes off, the lock would unlock, otherwise, the lock would stay locked until the time set on the timer was over.

If there is anyone that can help me work through the schematics of getting a relay to turn off the power to a 120 volt recep based on getting a 12 volt signal, it would be greatly appreciated. PM me if you want.

[kyrah]

NC = normally closed, which means when the relay has no voltage at the coil NC and POLE are connected

1 wire from your 120v goes straight to the timer and the other 120v wire goes to the NC connection on the relay
and a wire from POLE connection on the relay goes to the other connection on the timer switch.

the two connections to the coil on the relay would go to the connections on the siren, but there might be other
outputs on the alarm box you can use instead, so when all is well and the alarm is off the relay would be closed
and the power is able to reach the timer, when the alarm goes off it energises the relay, and opens the contacts
and the power cant reach the timer anymore., silencing the alarm would reset the relay to normally closed.

[RAE123]

At my Legion Post, we have a Kitchen with a Fire extinguisher for the stove area.
Now when the fire alarm goes off, the breaker for the fryers's goes off also.
It happens to be a Square "D" brand circuit breaker, but other makes have them as well.
It is called a external trip breaker; that is a out side source will trip the breaker not
necessary a short circuit.
You will have to go to a commercial electrical supply store or some place like "Granger"
Rae

[justDIY]

There's plenty of information on the Internet for controlling a 120 v outlet with a 12 v relay, which is what you're after.

Best bet is hire an electrician to wire an outlet for you at the electric panel that turns off when the alarm is tripped. Then run an extension cord from that outlet to your timers (please use more than one) and from there to the lock.

Are you sure your lock is 120 v? Most of them are 12-24 volts some AC some DC, some it doesn't matter.

[DarkLizerd]

When in doubt, go with a pro...
If you cell does not look like a cell, just a storage room, have the electrician wire you an outlet
close to your cell...

[SergioUK]

Tell him it's for a small pottery kiln or some other hobby-related heating device and you want to make sure that it turns off if the alarm is triggered.

On the timers, I use an electronic timer plugged into a mechanical one. The mechanical one is set for a much longer period than I might want to play (or not play) for and the electronic one for the exact time. If the electronic one fails (or more likely, I mess up the programming) the mechanical one should still cut the power some time later. I'm working on what's basically a junction box that routes the power via a smoke detector and a movement sensor set up outside my room so triggering either of those will also cut the power. I also have a 'safety person' arranged to visit but they don't know so that's a backup I can only use once, and neighbours within shouting distance. You can't have too many failsafes.

[buck100]

Whole new idea. Use a magnetic door lock. Most of them use 12 volts to hold the door locked so it is fail safe when the power fails. You can get locks requiring more than 300 lbs force to open. You won't get out. Look on Amazon.

I have one on the ceiling of my playroom. It is hooked to a digital timer and drops a key when the time expires. I think it is great.

Buck