Re: Computer control of an audio multiplexor

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Tue, 04 Dec 2007 11:49:30 -0500, Lewis Gardner
<lgardner@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
<47558519$0$2733$d94e5ade@xxxxxxxxxxxxxx>:

>Marc_F_Hult wrote:
>
>> The "cheapest" is not likely to be the "most flexible".  Nor is the
>> "easiest" ?  Which of these superlatives is most important to you ?

>I thought I had already laid out the economics of the situation for Mr.
>"User". For what it appears he wants to do buying a used RS232
>controlled matrix is the most cost effective method.

Agreed. A 'dumb' RS-232 switcher would be a good solution. But probably not
also the "most flexible" ;-)

>I recommended an
>AutoPatch unit off eBay ($160) or one of your Ivie 784PW units ($70).

If he needs six stereo channels, he would need two Ivie's because they are
8-in 4-out mono that can be combined for 16-in 8-out mono.

>Either of these devices are ready to go with well documented protocols.
>Buy it, hook it up, and you are good to go. I may have opted for a RS232
>controlled relay card but all I could find had SPDT relays and he wants
>stereo which would involve modification and expense.

The original poster, Joe User <axyz@xxxxxxxxx>, subsequently wrote that "In
my work, I do that sort of thing all the time.  I can buy switching
instruments from National Instruments to implement any kind of switching
matrix.".

So the $25 National Instruments 24-bit parallel I/O cards that are also
excess to my needs and also are at www.ECOntrol.org/porch_sale.htm might
work well for him. It wouldn't take that much more to drive relays with
them. Depends on the emphasis on "cheapest":  $25 + cost of relays + driver
IC < $160 .

Combine the free or low-cost electronic PCB and microcontroller programming
tools available with the ready access to dirt-cheap components (eBay is
amazing!), and one has the ingredients to make a wide range of HA hardware
very cheaply in terms of both $ _and_ time. I betcha I could design and
submit for pcb fabrication over the Internet a relay board in less than an
hour using parts available in my 'junk box or through a few clicks on the
net. I could spend that long jist trying to find the 'ideal' ready-made
thing retail on the net.

>If you count your time there is little savings in fabricating anything
>at those prices, especially yours!

Thanks. I'm not trying to make money, just clear off the 'porch' (a
metaphorical reference to junk cluttering  actual front porches in the
region/state I live in ;-) I also sometimes run across bargains on
hard-to-find DIY parts and have occasionally purchased more than I needed
on purpose.

For example, I just bought 48 150-amp split-core RU/UL current transducers
that are compact and ideal for power monitoring of 200-amp AC service. I am
working on  Power= V*I  PCB using a $3 AVR microcontroller that I will post
along with other similar stuff like this:
www.econtrol.org\4-inputbufferwith1wire.htm

Just my perspective ... Marc
Marc_F_Hult
www.ECOntrol.org