How to

[JohnMcConnell]

without buying expensive equiptment like manufactured base stations, is there some way I can connect a ring main of cable to 4 pin XLR plugs for an intercom system?

 

cheers, trying to set up a system in an old hall on the cheap :** laughs out loud **:

[Brian]

Hi John,

 

are you trying to do it without base stations AND belt packs? So you just need a cheap base station replacement? If so have a look at Tech Pro PSU info.

 

If you are trying to do it without beltpacks as well it gets a bit more difficult. An awesome resource contains shed-loads of circuits and info.

[andystone]

I assume you've tried string and empty baked bean tins?

[Andrew C]

Slightly more seriously, if you really want to go cheap, you can use old telephone handsets wired in series with a battery. Can't remember any details (last did it 20+ years ago) but the type of handset is probably important as would be the number, and also the voltage applied.

 

Someone may be better placed for details...

[Tomo]

Telephones use about 48v DC across two conductors - the other two are not essential.

The two pins in the phone line connector that you use are the ones that are used in the cheap modem cables. (Pins 3 and 4 I think)

 

Put a 48v DC source through a low-pass filter into the system, plug all the phones in in parallel along the line and you have yourself a 'party line' telephone system.

If you want more than 4 or 5 phones on the line, you'll need thicker conductors than the standard telephone cable.

I *believe* that the individual telephones draw about 0.5A each, so your power supply will have to be capable of supplying at least that much, and have an fuse on the output to reduce the likelihood of shorts causing ire.

 

You can even make them ring by switching 110v onto the line - that's a very powerful technique to make telephones ring on stage as well.

 

 

(Please note - I'm absolutely knackered right now and so there may be typos and innaccuracies in the above post)