telephone intercoms with ringer

[myp71]

Would anyone know how to hook up a telephone ringer and intercom together I have these circuits but I was wanting to know if there is a way when I pick up the phone on end#1 the other phone will ring end#2 and the other way around then when both phones are off hook they will switch over to my intercom circuit then when they are hung up they will go back to the ring circuit so the other side can call<p>thanks in advance
Ryan
Myp71

[Externet]

Hi Ryan<p>Very interesting... tempting challenge... I have to get involved in this. <p>With the goal being the simplest possible:<p>Using only one twisted pair, there is a chance to do it IF you can come up with a couple of DC buzzers with a specific behavior:<p>1.- Both DC buzzers connected in series will NOT buzz when your intercom battery is applied.<p>2.- With both DC buzzers in series; if one of them is shorted the other DOES buzz when the intercom battery is applied.<p>3.- Or, DC buzzers with zener diodes in series in such way they will NOT buzz unless all the intercom battery voltage gets applied.<p>Now, the connections:<p>A 12 V battery pack in SERIES with ONE of the twisted pair wires between the telephones.<p>Each of the above buzzers in PARALLEL to a normally open contact of the cradle switch at each telephone. (Open when on-hook)<p>-Observe polarities-<p>Parts needed
-12V Battery pack
-2 specific DC buzzers<p>Now, you mentioned you have a telephone ringer.
Did you mean you have a telephone ring signal generator of about 90VAC at ~20 Hz,
or you mean you have the telephone bells or electronic announcer chime ?<p>Let's see what happens.
Miguel

[myp71]

Hi Miguel,
Yes I have the telephone ring generator. Right now I'm using switches to switch over to the ring generator and telephone intercom circuit. I'm thinking that this circuit will use like two relays with n.c and n.o contacts but after that it is where i loose it.This is a real treat for someone like you to get this involved like this.<p>
Thanks in advance
Ryan
Myp71<p>[ May 05, 2003: Message edited by: my p71 ]<p>[ May 05, 2003: Message edited by: my p71 ]</p>

[myp71]

You know any help is welcomed <p>
Thanks in advance
My p71
Ryan

[Externet]

Hi.
To use a single ring generator in your project, you need a ~20mA current sensing relay on the loop.
When there is current present, the ringen is disabled or turned off by this current sensing relay.
When there is no current due to one of the telephones being on-hook, the ring voltage will act on the on-hook telephone bell via the enabling cradle switch.
You will have to implement a 4 wire between the telephones and extra relays to isolate the calling handset fron the ringing voltage.
Miguel

[myp71]

Thanks but I think I will pass too much money $90.00+ <p>[ May 08, 2003: Message edited by: my p71 ]</p>

[Stevereno]

Just a suggestion... Check this out:<p>Automatic Telephone Ringdown<p>Granted, it's $90, but it looks like it'll do what you want and uses just a single copper pair between the instruments.

[myp71]

Thanks for the last post and everyone that helped. It must be very hard too do I thought that you could just use the button that hangs up the phone somehow, but if they sell this really expensive stuff to do this it must be really hard.
who would have guessed <p>Myp71
RYAN<p>[ May 08, 2003: Message edited by: my p71 ]</p>

[frhrwa]

IF, and that's a big IF... your using the older 2500 or 500 type set... this is back when they made phones! They have hookswitch contacts, lots of them.. they connect you to the network inside the phone, they connect the ringer, etc... there are n/o, n/c, and combo contacts on the hookswitch.. if this isn't a regular dial tone phone, you can reconfigure these leads to do a lot of things.. I used some on phones close to speakers to mute the speaker when you took the phone off hook.. you can use them as annunciators, you could probably put your ringer on a set, then your supply on a n/o set, coming off hook would close them putting the ring voltage out to the other phone which would ring until answered, where upon the n/c set would go open when you come off hook removing the ringing... and vice versa... I can dig out the old drawings of a 2500 set and tell you what color combo to use to accomplish this, but remember, without an interuptor, you'll have constant ringing.. unless your supply puts out bursts... another option is an intercom box, and I may have some, they are about 5"X6"X1", very small, compact, require a key system power supply... which should be easy to come by.. they signal with the touch tone pad.. you can have stations all through your house... I'll look around and scrounge one of those up if you want it.. wayne

[myp71]

HI,
I'm using two new phones so I do not know if thats them or not but I'm kinda sure that these phones have n/c and n/o contacts so i would think that it would work but my little pea brain gets all confused on how to hook it up after that.Also my circuit that I have does have a timer on it so it rings like a regular phone.<p>Thanks for your help
Myp71
Ryan