Intercoms

[Macka]

Does anyone know of an intercom circuit that allows several stations to communicate at once? (no switching, just everyone can hear everything)

I was thinking it may be possible to use this circuit https://www.redcircuits.com/Page78.htm but modified so all stations are setup the same and have a repeater station.

eg
(full duplex - if possible) (full duplex - if possible)

St1 <--------------------->Repeater <-----------------------> St2
^
(full duplex - if possible) |
|
St3

If St1 talks the repeater will send the signal to St2 and St3
If St2 talks the repeater will send the signal to St1 and St3
If St3 talks the repeater will send the signal to St1 and St2

Is it possible? if not, would it be possible to do this in half duplex?

Anyone have any circuits that do roughly what I'm after?

I know you can get professional comms systems that do this and you can daisy chain 3 comms stations together and connect a number of these chains to a single "main station"/Control box

 

[raybo]

go to westinghouse and look at what they have

 

[audioguru]

You don't want a bunch of intercom stations to be loudspeaking and be full duplex. All the microphones will pickup background noise, echoes and present much more of a chance for acoustical feedback howling. The gain of the microphones or the speakers must be reduced to compensate.

The RED circuit might work if each station had an audio mixer for all the rest of the stations' anti-feedback connection. Their wiring (shielded) would be a nightmare.

You can have a bunch of stations as full dupolex if the microphones are close-talking and use headphones.

 

[Macka]

dont worry, i wouldnt dream of not using headphones. but it doesnt matter now anyway, the school finaly decided that kiddies walkie-talkies werent adequate (took them 5 years) and now have proper radios.

 

[ataul]

Does anyone know of an intercom circuit that allows several stations to communicate at once? (no switching, just everyone can hear everything)

I was thinking it may be possible to use this circuit https://www.redcircuits.com/Page78.htm but modified so all stations are setup the same and have a repeater station.

eg
(full duplex - if possible) (full duplex - if possible)

St1 <--------------------->Repeater <-----------------------> St2
^
(full duplex - if possible) |
|
St3

If St1 talks the repeater will send the signal to St2 and St3
If St2 talks the repeater will send the signal to St1 and St3
If St3 talks the repeater will send the signal to St1 and St2

Is it possible? if not, would it be possible to do this in half duplex?

Anyone have any circuits that do roughly what I'm after?

I know you can get professional comms systems that do this and you can daisy chain 3 comms stations together and connect a number of these chains to a single "main station"/Control box

Andrew
U try this . this is your circuit
se you...
ataul..

 

[The Mad Professor]

Other usefull information about this circuit such as a parts list can be found at "RED CIRCUITS"
https://www.redcircuits.com/Page78.htm