‎Using extra siren and entry sensors to interface to other sensors and alarm types | SimpliSafe Support Home
Jim's profile

40 Messages

Wednesday, February 9th, 2022 1:20 AM

Using extra siren and entry sensors to interface to other sensors and alarm types

It occurs to me that it would be pretty easy to connect some of the SS entry sensors and extra siren devices to other equipment to expand the functionality of the system.  For me as an electrical engineer this is really easy.  Here are two examples:

1) The entry sensor uses a magnetic reed relay switch internally, which provides an easy place to attach wires on each side to go to another user designed circuit for a user supplied sensor (USS) that presents the normally open condition when not activated and a closed circuit condition when the sensor is activated.  The classic example here are strip switch pads you place under the carpet to detect someone walking on the carpet in that location.  These carpet pads are normally open, and close when pressed with sufficient weight.  So an interface circuit that inverts the normally closed condition of the entry sensor is required.  This is pretty easy to do using a simple relay or an electronic circuit that inverts the NO/NC condition of the carpet pad.  If you do not have pets, these are much much more reliable than using motion sensors, you never get a false alarm from them (again, if you do NOT have pets).

2) For those of you who already have an old "bell box" mounted outside your house, it would be nice for the SS system to ring that bell when the system sounds an alarm inside the house.  This is easily achieved by using the SS Extra Siren to receive the alarm signal, then internally one can tap off the circuit board to close a relay or stimulate an electronic circuit that drives the bell box, using a 12 volt gel cell to power the bell box as is customary (bells take a lot of current).  The circuitry would also have an AC powered power supply and charger to keep the gel cell charged.  This is a more involved project but is easy for me.  Bell box alarms are easily recognized by other people as a burglar alarm going off, and would attract attention, and deter thieves pretty quickly, since all your neighbors will come out to look and see what the ringing is all about.

I am wondering how many SS users would have a need for such things?

2 years ago

100% yes.  I actually was just about to start building a prototype that would let folks reuse their existing hardwired door and window sensors by splicing them into modified SS entry sensors.  This is a huge use case - people get a new house / condo / apartment, the previous owner had an old alarm system, you call up any security company to install a new system and they all say the same thing: "oh instead of using those old wired sensors we'll just slap in these new wireless ones instead" even though the wired sensors provide a number of benefits if they're already in place (no batteries, no RF jamming possibilities, harder to detect / defeat with magnets since they're inside the frame and you can't see where they are without opening the door, etc). 

How many homes in America do you think are full of completely functional, AC powered safety and security hardware that's all just sitting there idle because one security company locked it down and another one told someone to abandon it?  Lots and lots and lots.

Imagine for a second a SS drop-in panel (or box, boxes are more user friendly) that could replace a pre-existing security panel, but actually give the owner full control like they deserve without having to dump EEPROMs to retrieve installer codes and jump through all of the old school zone programming hoops.  It would be AC powered plus a battery backup (you'll already have AC in the old panel box) and just communicate directly with the base station.  No one else offers anything like this.

Would it be more complicated to install?  Absolutely.  Would I attempt it myself?  For sure (and I probably already will, we're talking about an arduino, some lever nuts, half of an SS sensor and 20 minutes worth of coding to get started here).  Could SS make a bunch of extra cash from power users that want to leverage the hardware they already paid for, but would rather have a pro come and set everything up?  Very much yes...

1 Message

2 years ago

Can you tell me more about how you taped off the SS siren? Thanks.

40 Messages

@patcg60​ I haven't actually done it yet, but you would just tap into the wires feeding the alarm speaker itself (disconnect the speaker), and use that signal to drive a circuit that in turn drives the bell box bell.  The signal sent to the speakers is a high audio frequency AC signal, so you would put that through a full wave rectifier and a capacitor with a load resistor to convert it to a DC signal that goes from zero volts to probably about 5 volts when activated.  I have not looked at the waveform on a scope yet but I am guessing that its around that level.  Use that to either energize a relay that then enables the +12 volts to the bell (use a small relay that is easily energized, but that has a capacity of about 3 amps or more for the bell current), or do an electronic switching circuit that does the same (i.e., drive a power transistor or darlington with a series resistor in the base to set the drive current level).  It would be a very simple circuit.  You would also have circuitry to keep the 12 volt gel cell charged up from an AC source (such circuit designs are readily available on the internet for free).  While you are at it put a DC to DC converter circuit in that converts the 12V from the gel cell to the 6V the alarm sensor requires, so that you don't need to have the batteries around inside the alarm sensor.  Put it all including the gel cell in a basic Bud box and you are all set.  Use a 6" long quarter wave antenna attached to the alarm sensor internal antenna and have that stick out of the Bud box since the box would shield the RF signals otherwise.  You need to know how to design circuits like this so its a job for a EE or electronics hobbyist, not for ordinary people.

3 Messages

@Jim​ hey Jim, did you have any luck with this?


New to the Community? Get started by reading our Welcome Article and please be sure to review our Community Guidelines before posting.