[Asterisk-Users] door phone

[Adam Goryachev]

>> 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