🚀 go-pugleaf

In article <laird.721967281@stable.ecn.purdue.edu> laird@stable.ecn.purdue.edu (Kyler Laird) writes:
>I'm working on a paging module which "answers" a phone call as
>soon as it arrives (before a "ring" in generated for the calling
>party - quite confusing for some) and broadcasts the audio of the
>caller on speakers around the building for a preset time (LS7210
>digital delay - way cool).  The intent is that it can be used as
>a pager, outgoing line, and incoming line in response to the page.

This sounds pretty cool, maybe post block diagram.
>
>So far, it works beautifully feeding a Radio Shack amp/speaker
>module.  (and if you call 317-463-3447 while I'm working on it,
>you too will be a part of the testing...)

Al right, this is always fun to see results.
>
>I haven't ever tried distributing a signal like this.  I've read
>that I need to match my load (speakers) to my source (amp), but
>I'd like to use a cheap standard audio amp (8 ohm) and cheap
>little speakers (4 or 8 ohm).  I've seen speaker selectors with
>matching circuits built in, and would like to make something
>similar.  I'd like to keep it simple - resistors and transformers -
>if I can.  I'd also like to be able to add more speakers and vary
>the volume of each speaker (at the speaker  - parallel bus)
>without redesigning much.

Go back to the olden days (alright, maybe just comercial systems)
where everyone used 70 volt systems.  All the speakers are driven from
a high voltage/low current line.  (Works great for home stereo stuff
too, no more fat cable arguments).

Basically you need a step up transformer on output from the amplifier,
and step down transformers on all the speakers.


|-------|	  	  						speaker bus
|       |---|=|------------------------------------------------------------
|  amp  |	   	  		 |                    |              |
|       |  xformer       |      	     	  |	             |
|-------|	       xfmr |=|     	     	 |=|			|=|
				         |    /	   	   	      |    /		 | 	  /
				         |--||		  		  |--||			 |--||
				              \		  			   \			  \

					      4ohm speaker

The bad news, you have to be an electrician to install this system in
comercial buildings.  There is a practical limit to the number of
speakers you can hang off this bus, but if your amp has enough watts
you can drive a bunch of speakers.

give it a shot.

Tommy B.