[Asterisk-Users] door phone

[Jon Pounder]

Ok I guess I need to stop being lazy, and actually finish this project.

If you don't hear from me on the list about it in the next couple weeks,
bug me.

I'll complete the hardware, and take photos of it. (I have several loose
electric strikes besides the one on the front door so I can photograph
them and the electronics I build, and I will throw together some sort of
agi or system command that can be executed to activate the strike.)

By the way, not to keep you in suspense, but all inverse parallel means is
in a DC circuit the diode is installed in the direction that would
normally block current, but when the coil in the relay is de-energized,
and the magnetic field collapses this is the proper direction for the
diode to be pointed so it shunts the voltage spike across the coil and
keeps it out of the more sensitive solid state parts of the circuit.





>>> So, anyone got a solution for under AUD$100 ?
>>> Surely this is really just a bunch of cheap/commodity electronic
>>> components?
>
> asterisk-users-admin at lists.digium.com <> wrote:
>> I posted my solution yesterday and it is $50 so not sure why
>> people are still asking for a cheap solution.
>>
>> I have a cheap disposable "walmart" phone on the channel bank, in
>> immediate mode so when it is picked up it jumps immediately
>> to the default context.
>>
>> I can also dial it like any other extension to talk to people
>> at the door.
>
> OK, this part I understood/understand. It's "easy" and achieves a simple
> intercom (but depending on where you live, might cost you a LOT if you
> need to keep replacing the handset because people keep damaging it...
>
> Perhaps a cheap (as cheap as possible) speaker phone behind some sort of
> metal box with a grille where the speaker part is. Modify the 'hook'
> into a button and you are all done.
>
>> I have a $20 electric strike on the door which is coupled to
>> my burglar alarm (that I can use a keypad outside to open
>> right now) to interface to asterisk all I need is the
>> following about $5 worth of stuff.
>
> Yes, either someone sent it to the list, or I found a AUD$50 door strike
> for a 'standard' door. You say yours is interfaced to your alarm, what
> happens if you don't have an alarm? This seems to be the point where I
> keep getting confused.
>
>> 10k resistor from one of the data lines on the parallel port
>> to base of a 2n2222 transistor, emitter of 2222 to
>> ground/earth, collector to a coil of a 12vdc pcb mount relay,
>> 1n400x diode in inverse parallel with the coil to kill spikes,
>> other end of the diode/coil to 12vdc from a disk drive
>> connector in the pc. normally open contacts of the coil in
>> parallel with whatever else drives the door strike (normally
>> a 12-24AC/DC supply - AC if you like that Buzz, DC if a click
>> is more your liking.)
>
> I mostly understand that up to the inverse parallel but... I did some
> basic electronics stuff in school and in project kits, but never quite
> got up to IC's. Could you please consider making the above into some
> sort of circuit diagram/drawing?
>
>> Make a simple agi script either using system command or in C - output
> a 1
>> to the bit of the parport, wait 5seconds, output a 0. Done.
>
> This bit should be simple :)
>
>> Much less than $50 - parts avail - Radio Shack or Dick Smith (are they
>> still around in AU ?) Digikey is another fine source.
>
> Yes, Dick Smith are still around...
>
> So, I understand that there are a few components needed for this to
> work:
>
> Asterisk running on a pc with a parallel port (or maybe serial port?)
> Small electronic box described above which interfaces from the parallel
> port to <???>
> Door strike
>
> So, the bit I am missing is does the <???> mean your alarm panel, or
> does the electronic box connect directly to the door strike?
> What about some of these door strikes which can 'monitor' the door, can
> that information be passed back to asterisk? (I'm thinking turn on the
> lights etc when the door is opened with a key or forced open (can the
> door strike tell the difference?))
>
> Thanks for your help. I think this should be added to the wiki perhaps?
>
> Regards,
> Adam
>
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